Guide for the Design, Construction and Operation of
Electric Power Substations for Community Acceptance and
Environmental Compatibility<br>
North America, Africa, Asia, Europe, Australia.<br><br>



Guide for the Design, Construction and Operation of
Electric Power Substations for Community Acceptance and
Environmental Compatibility


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CONTENT
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FOREWORD......................................................................................... ii
ACKNOWLEDGEMENTS ........................................................................ ii
1. SCOPE AND PURPOSE .....................................................................1
1.1
Scope......................................................................................1
1.2
Purpose...................................................................................1
2.
REFERENCES..............................................................................2
3. DEFINITIONS................................................................................2
4. PLANNING STRATEGIES AND DESIGN............................................3
4.1 Site location, selection, and preparation...................................3
4.1.1 Site location and selection...................................................3
4.1.1.1 Wetlands........................................................................4
4.1.1.2 Site contamination ........................................................4
4.1.1.3 Potable water and sewage ............................................5
4.1.2 Site preparation...................................................................5
4.1.2.1 Gradient.........................................................................5
4.1.2.2 Sediment control ...........................................................5
4.1.2.3 Oil-spill containment and control ..................................5
4.1.2.4 Access roads ..................................................................6
4.1.2.5 Potable water and sewage ............................................6
4.1.3 Storm-water management ..................................................6
4.1.3.1 Upstream considerations...............................................6
4.1.3.2 Downstream considerations..........................................7
4.1.3.3 General design considerations......................................7
4.2 Aesthetics...................................................................................7
4.2.1 Visual simulation .................................................................7
4.2.2 Landscaping and topography ..............................................7
4.2.2.1 Landscaping...................................................................7
4.2.2.2 Topography....................................................................8
4.2.3 Fences and walls..................................................................8
4.2.3.1 Chain-link fences...........................................................8
4.2.3.2 Wood fences..................................................................8
4.2.3.3 Walls..............................................................................9
4.2.4 Colour ..................................................................................9
4.2.5 Lighting................................................................................9
4.2.6 Structures ............................................................................9
4.2.7 Enclosures..........................................................................10
4.2.8 Bus design..........................................................................10
4.2.8.1 Air-insulated substations ............................................10
4.2.8.2 Switchgear...................................................................10
4.2.8.3 Gas-insulated substations (GIS).................................10
4.2.8.4 Cable bus .....................................................................11
4.3 Noise........................................................................................11
4.3.1 Noise sources.....................................................................11
4.3.1.1 Continuous audible sources ........................................11
4.3.1.2 Continuous radio frequency (RF) sources ...................11
4.3.1.3 Impulse sources ..........................................................11
4.3.2 Typical noise levels............................................................11
4.3.2.1 Equipment noise levels................................................11
4.3.2.2 Ambient noise levels....................................................12
4.3.2.3 Attenuation of noise with distance .............................12
4.3.3 Governmental regulations.................................................14
4.3.4 Noise abatement methods.................................................14
4.3.4.1 Reduced transformer sound levels..............................15
4.3.4.2 Low-impulse noise equipment ....................................15
4.3.4.3 RF noise and corona-induced audible noise control....16
4.3.4.4 Site location.................................................................16
4.3.4.5 Larger yard area..........................................................16
4.3.4.6 Equipment placement..................................................16
4.3.4.7 Barriers or walls ..........................................................16
4.3.4.8 Active noise cancellation techniques..........................18
4.3.5 Community acceptance .....................................................18
4.4 Electric and magnetic fields.....................................................19
4.4.1 Electric and magnetic field sources in a substation ..........19
4.4.2 Electric fields .....................................................................19
4.4.2.1 Governmental regulations...........................................20
4.4.2.2 Reduction methods .....................................................20
4.4.2.3 Community acceptance...............................................20
4.4.3 Magnetic fields...................................................................20
4.4.3.1 Magnetic field measurements .....................................21
4.4.3.2 Magnetic field calculation methods.............................21
4.4.3.3 Governmental regulation ............................................22
4.4.3.4 Reduction methods .....................................................22
4.4.3.5 Community acceptance...............................................22
4.5 Safety and security ..................................................................23
4.5.1 Fences and walls................................................................23
4.5.2 Lighting..............................................................................23
4.5.3 Earthing or grounding .......................................................23
4.5.4 Fire protection ...................................................................23
5. PERMITTING PROCESS .................................................................23
5.1 Active community involvement ...............................................24
5.2 Low-key community involvement............................................24
6. CONSTRUCTION............................................................................24
6.1 Site preparation.......................................................................24
6.1.1 Clearing, grubbing, excavation, and grading ....................25
6.1.2 Site access roads ...............................................................25
6.1.3 Water drainage..................................................................25
6.1.4 Control methods ................................................................25
6.2 Noise........................................................................................25
6.3 Safety and security ..................................................................26
6.4 Traffic control...........................................................................26
6.5 Site housekeeping....................................................................26
6.6 Hazardous material..................................................................26
7. OPERATIONS.................................................................................27
7.1 Site housekeeping....................................................................27
7.1.1 Water and sediment control..............................................27
7.1.2 Yard surface maintenance.................................................27
7.1.3 Paint...................................................................................27
7.1.4 Landscaping.......................................................................27
7.1.5 Storage ..............................................................................27
7.2 Noise........................................................................................27
7.2.1 Continuous audible sources...............................................27
7.2.2 Impulse source ..................................................................28
7.3 Safety and security ..................................................................28
7.4 Fire protection..........................................................................28
7.5 Hazardous material..................................................................28


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This guide identifies significant community acceptance and environmental compatibility items to be
considered during the planning and design phases, the construction period, and the operation of electric
supply substations, and documents ways to address these concerns to obtain community acceptance and
environmental compatibility. On-site generation and telecommunications facilities are included.
1.2
Purpose
Approvals for new substations or even expansions of existing facilities can be subjected to extensive
review for community acceptance and environmental compatibility. A variety of permits are often
required by the regulatory bodies before construction of a substation may begin. Concerns are being
voiced by regulatory bodies and community groups in areas not considered necessary heretofore in the
permitting process. In some instances, land acquired for substations years in advance of construction is
deemed impossible to build on under present expectations and requirements.
This guide has been divided into three major parts with the goal of providing guidance on acceptable
practices for:
a) Planning strategies and design (Clause 4.);
b) Construction (Clause 6.); and
c) Operation of safe and reliable substations (Clause 7.).
For community acceptance and environmental compatibility, several considerations should be
satisfactorily addressed, including the following:
(a) Noise;
(b) Site preparation;
(c) Aesthetics;
(d) Fire protection;
(e) Pot able water and sewage;
(f) Hazardous materials;
(g) Electric and magnetic fields;
(h) Safety and security.

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<br>REFERENCES
This guide shall be used in conjunction with the following publications.
Environmental Protection and Pollution Control Act, Cap 204
Factories Act, Cap 441
ZS691, Guide for Safety in AC Substation Grounding.
IEEE Std 100-1996, The IEEE Standard Dictionary of Electrical and Electronics Terms.
ZS692, Guide for Substation Fire Protection.
ZS418 Electrical Safety Code
3.
DEFINITIONS

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<br>Definitions of terms pertinent to the subject matter are listed here. Definitions as given herein apply
specifically to the application of this guide. For additional definitions, see IEEE Std 100-1996.
3.1 A-weighted sound level
The representation of the sound pressure level that has as much as 40 dB of the sound below 100 Hz
and a similar amount above 10 000 Hz filtered out. This level best approximates the response of the
average young ear when listening to most ordinary, everyday sounds. Generally designated as dBA.
3.2 Commercial zone
A zone that includes offices, shops, hotels, motels, service establishments, or other retail/commercial
facilities as defined by Town and Country Planning Act.
3.3 Electrical substation
An enclosed assemblage of equipment, e.g. switches, circuit breakers, buses and transformers, under
the control of authorised persons, through which electric energy is passed for the purpose of switching
or modifying its characteristics
.
3.4 Hazardous material
Any material that has been so designated by Environmental Council of Zambia or adversely impacts
human health or the environment.
3.5 Industrial zone
A zone that includes manufacturing plants where fabrication or original manufacturing is done, as
defined by local ordinances.
3.6 Noise
Undesirable sound emissions or undesirable electromagnetic signals/emissions.
3.7 Residential zone
A zone that includes single-family and multi-family residential units, as defined by local ordinances.

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3.8 Wetlands
Any land that has been so designated by the
Ministry of Tourism, Environment and Natural
Resources. Characteristically, such land co
ntains vegetation associated with saturated types of
soil.
3.9 Zoning
Assigning as to a particular area having particular features, properties, purpose or use.

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4. PLANNING STRATEGIES AND DESIGN

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A project to successfully design, construct, and operate a substation begins with proper planning. The
substation’s location and proximity to wetlands, other sensitive areas, and contaminated soils; its
aesthetic impact; and the concerns of nearby residents over noise and electric and magnetic fields
(EMF) can significantly impact the ability to achieve community acceptance and environmental
compatibility. Public perceptions and attitudes toward both real and perceived issues can affect the
ability to obtain all necessary approvals and permits.
These issues can be addressed through presentations
to the regulatory bodies an
d the public.

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Deciding on the location of the site and where to place equipment on that site, inspections of the
proposed site for potential environmental problems, and measurement of ambient noise and EMF levels
are some of the steps that can be initiated early in the project. Failure to obtain community acceptance
can delay the schedule or, in the extreme, stop a project completely.
4.1 Site location, selection, and preparation
4.1.1 Site location and selection
The station location (especially for new substations) is a key factor in determining the success of any
substation project. Initially, the site location will be selected based on developing electrical loads, the
proximity of nearby electric transmission and distribution lines, costs, accessibility, and consultation
with governmental regulatory bodies. It is possible that major projects can be delayed or blocked by
public opposition. In some instances, substations may be built but never used.
The final site location may ultimately depend upon the ability of the user to successfully satisfy the
public and resolve potential community acceptance and environmental compatibility concerns. If the
user determines it is prudent to involve the public in the decision-making process of site selection, a
proactive public involvement program should be developed and implemented. The best site location
and placement of the substation on that site are influenced by several factors, including but not limited
to the following:a) Community attitudes and perceptions;
b) Location of nearby wetlands or bodies of water or environmentally sensitive areas;
c) Site contamination (obvious or hidden);
d) Commercial, industrial, and residential neighbours, including airports;
e) Permit requirements and regulations;
f) Substation layout (including future expansions) and placement of noise sources;
g) Levels of electric and magnetic fields;
h) Availability and site clearing requirements for construction staging;
i) Access to water and sewer;
j) Drainage patterns and storm water management;
k) Potential interference with radio, television and other communication installations;
l) Disturbance of archaeological, historical, or culturally significant sites;
m) Underground services and geology;
n) Accessibility;
o) Aesthetic and screening considerations.

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4.1.1.1 Wetlands
The design of any new substation should protect wetlands and ground water from sedimentation runoff,
oil spills, and changes in storm water discharge flows. Mapping wetland boundaries and designing a
facility that will minimise construction activities within or adjacent to designated wetlands should be a
priority. Use of an alternative site where available should be strongly considered, as governmental
regulatory bodies may prohibit any disturbance to a designated wetland area. If no alternative exists to
utilising a wetland location, design consideration should be given to preserving and improving
surrounding wetlands as a compromise for community acceptance.
A site-development plan is necessary for a substation project that borders wetlands. Such a plan for the
site and its immediate surroundings should include the following:
a) Land-use description;
b) Grades and contours;
c) Location of any wetland boundaries and stream-channel encroachment lines;
d) Indication of flood-prone areas and vertical distance or access to ground water;
e) Indication of existing wildlife habitats and migratory patterns.
The plan should describe how site preparation will modify or otherwise impact these areas and what
permanent control measures will be employed, including ground water protection.
4.1.1.2 Site contamination
There are many substances that if found on or under a substation site would make the site unusable or
require excessive funds to remediate the site before it would be usable. Some of the substances under
consideration are as follows:
a) Polychlorinated biphenyls (PCBs);
b) Asbestos;
c) Lead and other heavy metals;
d) Pesticides and herbicides;
e) Radioactive materials;
f) Petrochemicals;
g) Dioxin;
h) Oil.
In addition to the above, any substance that the Environmental Council of Zambia (ECZ) has
determined to be a hazardous material should be considered. ECZ guidelines for the levels of these
substances should be used to determine if the substance is present in large enough quantities to be of
concern.
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As a minimum, all potential sites should be visited by personnel trained to spot potential contamination
sources at the site and from nearby areas. Soil samples from a substation site, as well as samples of the
materials used in the construction of any existing buildings or structures should be tested before
acquiring or developing the site to determine if any substance listed above is present in large enough
concentration to require removal. It should be recognised that substantial excavation and soil removal
and disposal are normally required due to the installation of foundations for new equipment and
structures.
The cost of this removal and disposal should be considered before acquiring or developing the site. If a
cleanup is needed, the acquisition of another site should be considered as ECZ can hold the current
owner or user of a site responsible for cleanup of any contamination present, even if substances were
deposited prior to acquisition. If a cleanup is initiated, all applicable ECZ guidelines and procedures
should be followed

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4.1.1.3 Potable water and sewage

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The substation site may need potable water and sewage disposal facilities.
Water may be obtained from water utilities or communal water sources or from private wells. The
quality of water supplied by utility or communal water sources is beyond the control of the substation
owner. The quality of water from private wells, however, can be controlled by location, depth, and
treatment. The limits on contaminants in well water should be in compliance with any applicable
National Water and Sanitat ion Council (NWASCO) regulations before the well water is used.
Sewage may be disposed of by sewerage utilities or septic systems, or the site could be routinely
serviced by portable toilet facilities, which are often used during construction. Where utilities are used
for water or sewer services, the requirements of that utility must be met. The utility may consider the
substation owner as a developer and apply the same requirements for water or sewer main extensions
that would be required of a typical developer before service taps can be made.
Septic systems, when used, should meet all applicable local and national regulations.

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4.1.2 Site preparation
4.1.2.1 Gradient
The selection of a design elevation for a substation yard should include consideration of environmental
factors in addition to construction and cost factors. A lower elevation in relation to surrounding terrain
and vegetation may improve concealment. This, however, can significantly increase the impact on
construction if the water table is high, if there is a ledge (projection)to be excavated and removed, or if
there is a flooding potential at the lower elevation. The finished gradient of the substation should be
designed to minimise flooding and presence of standing water on the substation site. The slope of a
substation yard should be designed to lessen erosion and sedimentation potentials and should retard oil-
spill containment in the more impermeable soils. A sloped yard will also lessen the extent to which
side-sloped or retaining walls are required to provide yard transition to the existing gradient. The slope
of the substation should not be excessive to allow easy access of vehicle and maintenance equipment
required for safe operation and maintenance of facilities.

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4.1.2.2 Sediment control
Sedimentation potential is more likely to exist on sites consisting of fine sand or silt, and sites that have
side slopes. A layer of medium to coarse sand or geo-textile fabric beneath a crushed stone surface can
minimise this potential within a substation yard area that is long and steeply sloped. For exterior side
slopes, the erosion potential increases with both the length and the steepness of the slope. Because
slope length decreases as the steepness increases, a common solution for overall economy and minimal
environmental impact is to provide the steepest structurally-stable slope, thus minimising slope length.
This is especially the case where existing tree screening is important. Secondary measures to curb slope
erosion include the installatio n of top-slope diversion channels and intermediate benches cut into the
slopes. Both of these measures require additional cleared space. A solution that does not take space is
the placement of a layer of medium to coarse sand over the finer materials and beneath the top soil.
This solution also assists in reducing the amount of moisture that could facilitate the growth of
unwanted vegetation.
Substation design should comply with erosion and sedimentation -control guidelines of the Ministry of
Tourism, Environment and Natural Resources (MTENR).
4.1.2.3 Oil-spill containment and control
The detection, control and containment of oil spills should comply with the requirements of the
Environmental Council of Zambia. Where local government regulations exist, the substation design
must also comply.

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4.1.2.4 Access roads
For environmental compatibility, access roads can be designed to be unobtrusive. Width can be limited
to one lane except for lay-by at intervals from 60 m to 120 m and widened to two lanes at vertical and
horizontal curves with short sight distances. Design shall consider requirements for the installation and
removal of the longest piece of equipment including maximum slope and turning radius for the
transporting equipment. An equipment removal plan should be prepared for all major equipment in the
substation prior to deciding upon appropriate access roads.
Where tree screening is available, horizontal curves can be provided to block the view of the substation
from the street. Long access roads are known to become meeting sites for illegal activities and dumping
of solid or hazardous wastes. These activities can be a concern to the nearby residents. The installation
of locked gates and fencing or vehicular barriers at access road entrances may be helpful in this
situation.
A satisfactory surfacing material is a well graded crushed stone. Roads can be hard paved if
a) Matching the appearance of neighbouring entryways is important;
b) Required by local regulations;
c) On a steep gradient subject to erosion;
d) Required for equipment transportation.
Roads should be provided with appropriate surface drainage control.
4.1.2.5 Potable water and sewage
These facilities should be designed using good engineering practices. The design should consider local
climate and soil conditions and provide systems that will not adversely affect ground water, adjacent
land owners, or inhabitants. Care should be taken during the design of the substation to prevent the
possibility of hazardous discharges, when present , from entering ground water, drains, or the
substation’s sewer system. Septic tank design should not interfere with buried ground and power
distribution during installation and maintenance.

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4.1.3 Storm-water management

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Where rapid erosion by storm-water flow entering or leaving a substation yard is not a problem,
sedimentation-control features of substation design will be adequate by themselves. Where this is a
potential problem, site design should, to the extent possible, minimise changes to the natural flow of
storm water entering and leaving the site. Open storm water -flows across the substation yard should be
avoided. Drainage should be designed to route water runoff from the substation to designated places to
avoid flooding of access roads and nearby areas. Storm-water management must conform to regulatory
requirements.

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4.1.3.1 Upstream considerations
It is necessary to consider stream floodways where construction may be discouraged, prohibited or
where it is subject to approval by a regulatory authority. Information about flooding may be available
from local authorities. If the substation site is outside a floodway zone, the most frequent source of
concern is when the site includes stream control measures for a wetland that must be maintained.
Lowering or raising the elevation of this control affects the water level in the wetland. Since the
position of the control may, in the future, vary with the quantity of flow, the control must be located,
and its position preserved, throughout the entire range of stream flows. A substation yard should not be
situated where control would be affected. However, the access road may sometimes be permitted to
remain in the general area of the control if it is situated exactly at existing gradient, and any stream
crossing is made with a bridge. For wetland preservation, such a bridge and its abutments need to be
outside of the watercourse during normal flows, but not necessarily outside of the stream’s floodway.
This same bridge concept can be used to help preserve existing conditions downstream.

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4.1.3.2 Downstream considerations
It is often necessary to select those aspects of drainage changes which are least likely to adversely
affect critical downstream activities. The design should hold changes to a minimum at the point of
these activities, even at the expense of greater changes for less sensitive areas. The most common
problem is the acceleration of runoff due to pipe flow channelisation, elimination of natural hills by
smooth gradients, and hard paving. Corrective flow-retarding measures include providing rough
channel bottoms, usually in the form of large angular rocks, lengthening channels and thereby
decreasing slopes, and retention basins. Excessive retention will rarely cause a downstream problem
except in extremely arid areas where evaporation is significant.

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4.1.3.3 General design considerations
Where space allows, open ditch storm-water systems are generally preferable to pipe systems because
they are less costly, minimise blockage problems, and usually provide better retardation of runoff. The
possibility of oil spills or the contribution of degreasers or solvents should be considered in storm-
water system designs. The consequences of not having adequate storm drainage within a working area
are usually limited to temporary shallow flooding. This can be mitigated by applying additional
crushed stone to problem areas. Underground storage systems may be a cost-effective alternative when
space is a concern.

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4.2 Aesthetics
It is helpful to develop an aesthetic image of the substation so that it can be accepted by the
community. Sites can be selected that fit into the context of present and future community patterns.
Community acceptability of a site is influenced by
a) Concerns about compatibility with pres ent and future land uses;
b) Building styles in the surrounding environment;
c) Landscape of the site terrain;
d) Allowance for buffer zones for effective blending, landscaping, and safety;
e) Site access that harmonises with the community.
In addition, the site may need to be large enough to accommodate mobile emergency units and future
expansions without becoming congested and therefore be perceived as untidy and displeasing.
4.2.1 Visual simulation
Traditionally, site rendering was an artist’s sketch, drawing, painting, or photomontage with airbrush
retouching, preferably in colour, as accurate and realistic as possible. In recent years, these traditional
techniques, although still employed, have given way to two- and three-dimensional computer-generated
images, photorealism, modelling, and animation to simulate and predict the impact of proposed
developments.
This has led to increased accuracy and speed of image generation in the portrayal of new facilities for
multiple-viewing (observer) positions, allowing changes to be made early in the decision-making
process while avoiding costly alterations that sometimes occur later during construction.

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4.2.2 Landscaping and topography

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4.2.2.1 Landscaping

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Where buffer space exists on site to provide vegetative concealment of a substation, landscaping,
especially as a supplement to natural vegetative screening, is a very effective aesthetic treatment. On a
site with little natural screening, plantings can be used in concert with architectural features to
complement and soften the visual effect.

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<br>Shrubs, hedges, and other small plantings are useful for low coverage, fill-in, and accent. These should
be employed informally and with variety. Low-ground cover and grasses are effective on berms and in
ditches. When planted on top of berms, the impact of the landscaping plantings can be immediate for
screening purposes. Trees that give excellent coverage and colour, and can be used in clusters, in
hedges, or spaced apart should be considered. Size should be sufficient for the screening purpose but
not so large as to endanger overhead lines. Species selection should avoid animal or bird attractant
types that create a hazard to the function and safety of equipment or personnel.
All plantings should be locally available and compatible types, and should require minimum
maintenance. Their location near walls and fences should not compromise either substation grounding
or the security against trespass by people or animals.

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4.2.2.2 Topography

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Topography or land form, whether shaped by nature or by man, can be one of the most useful elements
of the site to solve aesthetic and functional site development problems.
The first and foremost consideration is to carefully examine the immediate environment of the
substation site to discover natural land forms that can influence how the site itself is moulded and
landscaped. For example, some sites may have a hillside backdrop that would absorb the skyline view
or foreground slopes that influence the primary observation zone. Environmental topography design
should consider the effect of screening, horizontal setback, and the background screen on the primary
observation zone.
Aesthetically, the land form within the site should reflect or blend with the topography of its
environment. The use of land form should be carefully evaluated in combination with plant materials.
The careful and sensitive blending of these two important elements can result in a meaningful site
development. Trees and shrubs can be less massive and numerous when combined with ground forms
of various shapes.
The shape of topography will vary with each situation. The gentle soft forms might be entirely fitting
for the wide open countryside, whereas more tailored, sculptured forms might be compatible with an
urban setting.
Use of topography as a visual screen is often overlooked. Functionally, earth forms can be permanent,
visual screens constructed from normal on-site excavating operations. When combined with plantings
of grass, bushes, or evergreens and a planned setback of the substation, berms can effectively shield the
substation from nearby roads and residents. Appreciable cost savings can be realised by utilising cut
material spoil on the site for earth forms rather than removing it from the site.

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4.2.3 Fences and walls

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The Electrical Safety Code ZS 418 requires that fences, screens, partitions, or walls be employed to
keep unauthorised persons away from substation equipment.

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4.2.3.1 Chain-link fences

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This type of fence is the least vulnerable to graffiti and is generally the lowest-cost option. Chain-link
fences can be galvanised or painted in dark colours to minimise their visibility, or they can be obtained
with vinyl cladding. They can also be installed with wooden slats or coloured plastic strips woven into
the fence fabric. Earthing or grounding and maintenance considerations should be reviewed before
selecting such options.

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4.2.3.2 Wood fences

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This type of fence should be constructed using naturally rot-resistant or pressure-treated wood, in
natural colour or stained for durability and appearance. A wood fence can be visually overpowering in
some settings. Wood fences should be applied with caution because wood is more susceptible to
deterioration than masonry or metal.

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4.2.3.3 Walls
Although metal panel and concrete block masonry walls cost considerably more than chain-link and
wood fences, they deserve consideration where natural or landscaped screening does not provide a
sufficient aesthetic treatment. Each of these options is available in a range of types, shapes, and
colours, and can be used in combination for an attractive architectural appearance. Brick and pre-cast
concrete can also be used in solid walls, but these materials can be far more expensive. These materials
should be considered where necessary for architectural compatibility with neighbouring facilities.
Walls can be subject to graffiti, and this should be part of the consideration of their use.
4.2.4Colour
When substations are not well screened from the community, colouring should be considered to
improve the visual effects.
Above the skyline, the function of colour is usually confined to eliminating reflective glare from bright
metal surfaces. Because the sun’s direction and the brightness of the background sky vary, no one
colour can soften the appearance of substation structures in the course of changing daylight.
Below the skyline, colour can be used in three aesthetic capacities. Drab colouring, using earth tones
and achromatic hues, is a technique that masks the metallic sheen of such objects as chain-link fences
and steel structures, and reduces visual contrast with the surrounding landscape. Such colouring should
have very limited variation in hues, but contrast by varying paint saturation is often more effective than
a monotone coating. Colours and screening can often be used synergistically. A second technique is to
use colour to direct visual attention to more aesthetically pleasing items, such as decorative walls and
enclosures. In this use, some brightness is warranted, but highly saturated or contrasting hues should be
avoided. A third technique is to brightly colour equipment and structures for intense visual impact.
4.2.5 Lighting
When attractive landscaping, decorative fences, enclosures, and colours have been used to enhance the
appearance of a highly visible substation, it may also be appropriate to use lighting to highlight some of
these features at night. Lighting of such exterior features may be accomplished with ornamental
lighting, garden lighting, floodlights , or architectural lighting. Generally, such lighting is more
appropriate for larger substations in commercial-industrial areas. In a residential area, lighting that
differs from the lighting used on neighbouring residential properties or unnecessarily focuses attention
on the substation is likely to be unwelcome. Although all-night lighting can enhance substation security
and access at night, it should be applied with due concern for nearby residences.
4.2.6Structures
The importance of aesthetic structure design increases for structures that extend into the skyline. The
skyline profile typically ranges from 6 m to 10 m above ground. Transmission line termination
structures are usually the tallest and most obvious. Use of underground line exits will have the greatest
impact on the substation’s skyline profile. Where underground exits are not feasible, low-profile station
designs should be considered. The visual impact of the structures is reduced if a low-profile design is
used. Often the substation with low-profile structures can be brought below the nearby tree line profile.
For additional cost, the most efficient structure design can be modified to improve its appearance. The
following design ideas may be used to improve the appearance of structures:

<br>
<br>

a) Tubular construction;
b) Climbing devices not visible in profile;
c) No splices in the skyline zone;
d) Limiting member aspect ratio for slimmer appearance;
e) Use splices other than pipe-flange type;
f) Use of gusset plates with right angle corners not visible in profile;
g) Tapering ends of cantilevers;
h) Equal length of truss panel;

<br>
<br>

i) Making truss diagonals with an approximate 60° ?angle to chords;
j) Use of short knee braces or moment -resistant connections instead of full-height diagonal
braces;
k) Use of lap splice plates only on the insides of H-section flanges.

<br>
<br>

4.2.7 Enclosures

<br>
<br>

Total enclosure of a substation, within a building that may serve other non-utility needs, is an option in
urban settings where underground cables are used as supply and feeder lines. Enclosure by high walls,
however, may be preferred if enclosure-type concealment is necessary for community acceptance.
A less costly design alternative in non-urban areas that are served by overhead power lines is to take
advantage of equipment enclosures to modify visual impacts. Relay and control equipment, station
batteries, and indoor power switchgear all require enclosures. These enclosures can be aesthetically
designed and strategically located to supplement landscape concealment of other substation equipment.
The exterior appearance of these enclosures can also be designed (size, colour, materials, shape) to
match neighbouring homes or buildings.
Industrial-type, pre-engineered metal enclosures are a versatile and economic choice for substation
equipment enclosures. Concrete block construction is also a common choice, for which special shaped
and coloured blocks may be selected to achieve a desired architectural effect. Brick, architectural metal
panels, and pre-cast concrete can also be used.
Substation equipment enclosures usually are not exempt from local building codes. Community
acceptance, therefore, requires enclosure design, approval, and inspection in accordance with local
regulation.

<br>
<br>

4.2.8Bus design

<br>
<br>

Substations can be constructed partly or entirely within above-ground or below-ground enclosures.
However, cost is high and complexity is increased by fire-protection and heat-removal needs. Bus
design for such facilities is not a community aesthetic concern, so this sub -clause is limited to exposed
above-ground substations.

<br>
<br>
4.2.8.1 Air-insulated substations

<br>
<br>

The bus and associated substation equipment are exp osed and directly visible. An outdoor bus may be
multi-tiered or spread out at one level. Metal or wood structures and insulators support such bus and
power line terminations. Space permitting, a low -profile bus layout is generally best for aesthetics and
is the easiest to conceal with landscaping, walls, and enclosures. Overhead transmission line
terminating structures are taller and more difficult to conceal in such a layout. In dry climates, a low -
profile bus can be achieved by excavating the earth area, within which outdoor bus facilities are then
located, for an even lower profile.

<br>
<br>

4.2.8.2 Switchgear

<br>
<br>

Metal-enclosed or metal-clad switchgear designs that employ either air or other insulation systems
house the bus and associated equipment in a metal enclosure are an alternative design for distribution
voltages. These designs provide a compact low-profile installation that may be aesthetically acceptable.

<br>
<br>

4.2.8.3 Gas-insulated substations (GIS)

<br>
<br>

Bus and associated equipment can be housed within pipe-type enclosures using sulphur hexafluoride or
another similar gas for insulation. Not only can this achieve considerable compactness and reduced site
preparation for higher voltages, but it can also be installed lower to the ground. A GIS can be an
economically attractive design where space is at a premium, especially if a building-type enclosure will
be used to house substation equipment.

<br>
<br>
4.2.8.4 Cable bus

<br>
<br>

Short sections of overhead or underground cables can be used at substations, although this use is
normally limited to distribution voltages (e.g., for feeder getaways or transformer-to-switchgear
connections). At higher voltages, underground cable can be used for line-entries or to resolve a specific
connection problem.

<br>
<br>
4.3 Noise

<br>
<br>

Audible noise, particularly continuously radiated discrete tones (e.g., from power transformers), is the
type of noise that the community may find unacceptable. Community guidelines to ensure that
acceptable noise levels are maintained can take the form of governmental regulations or
individual/community reaction (permit denial, threat of complaint to utility regulators, etc.). Where
noise is a potential concern, field measurements of the area ambient noise levels and computer
simulations predicting the impact of the substation may be required. The cost implications of the
mitigation methods (low -noise equipment, barriers or walls, noise cancellation techniques, etc.) may
become a significant factor when a site is selected.
Noise can be transmitted as a pressure wave either through the air or through solids. The majority of
cases involving the observation and measurement of noise have dealt with noise being propagated
through the air. However, there are reported cases of audible transformer noise appearing at distant
observation points by propagating through the transformer foundation and underground solid rock
formations. Since the occurrence of this is rare, there is no technical analysis or empirical data
available to predict the likelihood of occurrence. It is best to avoid the situation by isolating the
foundation from bedrock where the conditions are thought to favour transmission of vibrations.

<br>
<br>

4.3.1 Noise sources

<br>
<br>
4.3.1.1 Continuous audible sources

<br>
<br>

The most noticeable audible noise generated by normal substation operation consists of continuously
radiated audible discrete tones. Noise of this type is generated primarily by power transformers.
Regulating transformers, reactors, and emergency generators, however, could also be sources. This
noise is the type most likely to be subject to governmental regulation. Another source of audible noise
in substations is corona from the bus and conductors.

<br>
<br>

4.3.1.2 Continuous radio frequency (RF) sources

<br>
<br>

Another type of continuously radiated noise that can be generated during normal op eration is RF noise.
These emissions can be broadband and can cause interference to radio and television signal reception
on properties adjacent to the substation site. Objectionable RF noise is generally a product of
unintended sparking, but can also be produced by corona.

<br>
<br>

4.3.1.3 Impulse sources

<br>
<br>

While continuously radiated noise is generally the most noticeable to substation neighbours, significant
values of impulse noise can also accompany normal operation. Switching operations will cause both
impulse audible and RF noise with the magnitude varying with voltage, load, and operation speed.
Circuit-breaker operations will cause audible noise, particularly operation of air-blast breakers.

<br>
<br>

4.3.2 Typical noise levels

<br>
<br>

4.3.2.1 Equipment noise levels

<br>
<br>
Equipment noise levels may be obtained from manufacturers, equipment tendering documents, or test
results.
Transformer noise will “transmit” and attenuate at different rates depending on the transformer size,
voltage rating, and design. Few complaints from nearby residents may be typically received concerning
substations with transformers of less than 10 MVA capacity, except in urban areas with little or no
buffers. Complaints may be more common at substations with transformer sizes of 20–150 MVA,
especially within the first 170 –200 m. However, in very quiet rural areas where the night time ambient
can reach 20–25 dBA, the noise from the transformers of this size can be audible at distances of 305 m
or more. In urban areas, substations at 330 kV and above may not often result in many complaints
because of the large parcels of land on which they are usually constructed.
4.3.2.2 Ambient noise levels
The degree of annoyance with continuous audible noise is dependent in a large part upon the relative
level of the ambient noise. The human ear will normally only notice the dominant of several noises.
Sources of ambient noise in the community include vehicular or railway traffic, factories, aircraft,
animals, and appliances such as attic fans, air conditioners, and lawn mowers. If ambient noise is very
low, even a small amount of wind can override the other noise sources and become the dominant
ambient noise.
The human ear distinguishes a particular sound source and establishes whether it is objectionable or not
by comparing it to the general background or ambient noise to which it has become accustomed.
Ambient noise is generally a broadband noise that covers a large range of frequencies, with no
pronounced or outstanding tones. The addition of another broadband noise source, such as a fan, would
not likely be distinguishable by the human ear. Car horns, gun shots, and transformer noise, being more
or less of a pure tone, can readily be distinguished by the human ear if loud enough.
Common outdoor noise levels are shown in Table 1 on the following page.
Table 1— Common outdoor noise levels
Type
Noise level (dBA)
Jet flyover at 305 m
110
Gasoline lawn mower at 0.9 m
100
Diesel truck at 15 m
90
Noisy urban daytime
80
Gasoline lawn mower at 30.5 m
70
Commercial area heavy traffic at 90 m
60
Quiet urban daytime
50
Quiet urban night time
40
Quiet suburban night time
30
Quiet rural night time
20
Threshold of hearing
10
Source: Fundamental and Abatement of Highway Traffic Noise, BBN Corporation.
Highway traffic can provide a base ambient noise that can help to shield substation noise. While it is
easy to measure traffic noises near the highway, it becomes increasingly difficult to measure them at
distances of 1.5–3 km. A substation could benefit from the shielding effect of highway noise if it is
located less than 3 km from a highway.

<br>
<br>

4.3.2.3 Attenuation of noise with distance

<br>
<br>

The rate of attenuation of noise varies with distance for different types of sound sources depending on
their characteristics. Point sound sources that radiate equally in all directions will decrease at a rate of 6
dB for each doubling of distance. Cylindrical sources vibrating uniformly in a radial direction will act
like long source lines and the sound pressure will drop 3 dB for each doubling of distance. Flat planar
surfaces will produce a sound wave with all parts of the wave tracking in the same direction (zero
divergence). Hence, there will be no decay of the pressure level due to distance only. To determine the
effect distance will have requires the designer to first identify the characteristics of the source before
proceeding with the design.
A transformer will exhibit combinations of all of the above sound sources depending on the distance
and location of the observation point . Because of its height and width, which can be one or more
wavelengths, and its non uniform configuration, the sound pressure waves will have directional
characteristics with very complex patterns. Close to the transformer (near field), these vibrations will
result in lobes with variable pressure levels. Hence the attenuation of the noise level will be very small.
If the width (W) and height (H) of the transformer are known then the near field is defined, from
observation, as any distance less than
WH
2
from the transformer.
Further from the transformer (far field), the noise will attenuate in a manner similar to the noise emitted
from a point source. The attenuation is approximately equal to 6 dB for every doubling of the distance.
It never becomes a true point source since it retains some directional planar and cylindrical wave
characteristics. Consequently, the noise level will still vary with direction (i.e. full side view versus an
edge view) even if distance remains constant. Studies have shown that the sound pressure in a given
direction can deviate as much as 4 dB above or below the average noise level. The deviation will occur
over less than 10% of the circumference of the transformer. For overexcited transformers, the noise at
the tank and hence any observation point can be significantly higher than the noise level at rated
voltage. For far field effect, an equation has been developed to represent the attenuation of sound for
transformers as a function of the height and width of the main transformer tank. Since height and width
are generally proportional to the transformer voltage and capacity ratings, the equation has been further
modified to relate attenuation to these transformer ratings. Both equations can be readily plotted
graphically for comparison to ambient noise levels.
WH
D
dBT
N
log
20
4.
4
?
?
?
?
(1)
or
?
?
D
kVA
kV
dBT
N
log
20
)
)(
(
log
08
.2
2.
6
?
?
?
?
?
(2)
In both cases, far field is defined as
WH
D 2
?
where
N is noise (dBA) at a point distance D from the transformer;
dBT is specified noise level at the transformer (dBA);
kVA is transformer size (self-cooled rating);
kV is high-voltage winding (phase-to-phase);
W is width of main tank (m);
H is height of main tank (m);
D is distance from the transformer to the point of interest (m).
With respect to more than one transformer, the contribution of each source at the point of observation
should be calculated separately. The value of each is combined as the logarithmic sum of the two.
Figure 1 on page 20 may be used to approximate this logarithmic sum. If a transformer has a fan array,
the noise contribution of the fans can be calculated using the same equation where W and H are the fan
array dimensions. A designer should determine the need to add design margin to the layout of a new
station if transformer noise will be a concern.
For a distance less than
WH
2
, these equations will not apply as the sound pressure attenuation is
influenced by factors other than logarithmic reduction.

<br>
<br>

4.3.3 Governmental regulations

<br>
<br>

Governmental regulations may impose absolute limits on emissions, usually varying the limits with the
zoning of the adjacent properties. Such limits are enacted by the Environmental Council of Zambia
(ECZ) where limited buffer zones exist between property owners. Typical noise limits at the substation
property line used within the industry are as follows:
Industrial zone < 75 dBA
Commercial zone < 65 dBA
Residential zone < 55 dBA
Additional governmental noise regulations address noise levels by limiting the increase above the
existing ambient to less than 10 dB. Other regulations could limit prominent discrete tones, or set
specific limits by octave bands.
4.3.4 Noise abatement methods
It is beyond the scope of this guide to make recommendations as to which method of noise abatement
is best suited for specific applications due to the wide range of cost implications and site variables that
can exist. However, as an aid to those engaged in the design of noise abatement systems, several
examples of various types that have been used successfully are described in 4.3.4.1 through 4.3.4.8.
The likelihood of a noise complaint is dependent on several factors, mostly related to human
perceptions. As a result, the preferred noise abatement method is time dependent as well as site
specific. Placement of the substation in an isolated area with few neighbours may be initially
successful. However, development of the area during the life of the substation could result in additional
neighbours. In general, the existence of a substation prior to the arrival of new neighbours may not
prevent a noise complaint. On the other hand, increased development will probably bring with it an
associated increase in the background ambient, which may help to reduce the likelihood of a complaint.
In addition, the concept of change is important. When a new substation is built in a previously quiet
residential or rural area, the transformer noise will represent a noticeable change, with an increased
likelihood of being perceived as being an annoyance. Given enough time, its effect will become less
noticeable. People may become accustomed to continuous background noise such as airplanes landing
and taking off from nearby airports, and effectively tune out the background noise. A similar
psychological reaction to transformer noise can occur, which is one reason the addition of a second
transformer at an existing station may not generate community reaction to the increased noise.
If a second adjacent transformer produces an identical noise level to the existing transformer (e.g. 75
dBA), the total sound will be 78 dBA for a net increase of only 3 dB. This is due to the logarithmic
effect associated with a combination of noise sources. The graph shown in Figure 1 can be used to
determine the resultant noise level of two noise sources. Most people cannot perceive changes in noise
levels of 3 dB or less.

<br>
<br>

Figure 1— Nomograph for determining combination sound levels [from IEEE std 1127-
1998(R2004)]

<br>
<br>

4.3.4.1 Reduced transformer sound levels

<br>
<br>

Since power transformers, voltage regulators, and reactors are the primary sources of continuously
radiated discrete tones in a substation, careful attention to equipment design can have a significant
effect on controlling noise emissions at the substation property line. This equipment can be specified
with noise emissions below manufacturer’s standard levels, with values as much as 10 dB below those
levels being typical.
In severely restrictive cases, transformers can be specified with noise emissions 20 dB less than the
manufacturers’ standard levels, but usually at a significant increase in cost. Also, inclusion of bid
evaluation factor(s) for reduced losses in the specification can impact the noise level of the transformer.
Low-loss transformers are generally quieter than standard designs.

<br>
<br>

4.3.4.2 Low-impulse noise equipment

<br>
<br>

Outdoor-type switching equipment is the cause of most impulse noise. Switchgear construction and the
use of vacuum or puffer circuit breakers, where possible, are the most effective means of controlling
impulse emissions. The use of circuit switchers or air-break switches with whips and/or vacuum
bottles, for transformer and line switching, may also provide impulse-emission reductions over
standard air-break switches.

<br>
<br>

4.3.4.3 RF noise and corona-induced audible noise control

<br>
<br>

Continuously radiated RF noise and corona-induced audible noise can be controlled by the use of
corona-free hardware and shielding for high-voltage conductors and equipment connections, and
attention to conductor shapes to
avoid sharp corners. Angle and bar conductors have been used successfully up to 132 kV without
objectionable corona if corners are rounded at the ends of the conductors and bolts are kept as short as
possible.
Tubular shapes are typically required above this voltage. Pronounced edges, extended bolts, and abrupt
ends on the conductors can cause significant RF noise to be radiated. The diamet er of the conductor
also has an effect on the generation of corona, particularly in wet weather when water droplets disturb
the smooth surface of conductors. Increasing the size of single grading rings or conductor diameter
may not necessarily solve the problem. In some cases
it may be better to use multiple, smaller diameter, grading rings.

<br>
<br>

4.3.4.4 Site location

<br>
<br>
For new substations to be placed in an area known to be sensitive to noise levels, proper choice of the
site location can be effective as a noise abatement strategy. Obviously, a location isolated from all
neighbours will minimise the likelihood of a noise complaint. Where this is not possible, the advantage
of sites in high ambient noise level areas should be considered. Locations in industrial parks or near
airports, expressways, or commercial zones can provide almost continuous ambient noise levels of 50
dB or higher, minimising the likelihood of a complaint. Placement of substations near backdrop hills
may redirect the radiant sound as might su bstations set below gradient and surrounded by berms.

<br>
<br>

4.3.4.5 Larger yard area

<br>
<br>

Noise intensity varies inversely with distance. An effective strategy for controlling noise of all types
involves increasing the size of the parcel of real estate on which to locate the substation.

<br>
<br>
4.3.4.6 Equipment placement

<br>
<br>

Within a given yard size, the effect of noise sources on the surroundings can be mitigated by careful
siting of the noise sources within the confines of the substation property. In addition, making
provisions for the installation of mobile transformers, emergency generators, etc., near the centre of the
property, rather than at the edges, will lessen the effect on the neighbours.

<br>
<br>
4.3.4.7 Barriers or walls

<br>
<br>

If adequate space is not available to dissipate the noise energy before reaching the property line,
structural elements might be required. These can consist of walls, sound -absorbing panels, or
deflectors. In addition, earth berms or below-gradient installation may be effective. It may be possible
to deflect audible noises, especially the continuously radiated tones most noticeable to the public, to
areas not expected to be troublesome. Foliage, in spite of the potential aesthetic benefit and
psychological effect, is not particularly effective for noise reduction purposes.
Properly constructed sound barriers can provide several decibels of reduction in the noise level. An
effective barrier involves a proper application of the basic physics of
a) Transmission loss through masses;
b) Sound diffraction around obstacles;
c) Standing waves behind reflectors; and
d) Absorption at surfaces.
In general, materials with a high mass have a good transmission loss. As a general rule, it can be said
that if a barrier of sufficient height to shield the noise is constructed of a material that can support itself
and resist the wind load imposed upon it simultaneously, it will meet the transmission loss
requirements. Due to the sound diffraction around the barrier, materials and transmission losses greater
than 25 dB will not affect the new attenuation produced by the wall at large distances.
The height of the wall is determined primarily by the diffraction of sound around the wall. A
significant reduction in sound is obtained when the barrier extends approximately one wave length
[about 3.0 m at 120 Hz] above, as well as beyond the line of sight from the transformer centre to the
listener. Where a specific decibel reduction is desired or known, a more precise determination of the
height and length of walls necessary to alleviate the noise problem can be made. The formula for
calculating the necessary height and length of the walls is based on the Fresnel theory of the diffraction
of a point source of light over a knife edge. Wells and Fehr converted the Fresnel formula to express it
in terms of sound waves rather than light waves. In turn, sound engineers have transformed the Wells-
Fehr theorem into
the formula below.
?
?
7.
8
log
5.
9
2
2
120
?
?
?
?
R
h
R
dB
Hz
(3)
(For 240 Hz, add 7.7 to result of 120 Hz calculation; for 360 Hz, add 9.4 to result of 120 Hz
calculation.)
Where
R is the distance (m) from the geometric centre of the transformer tank to the inside surface of the wall;
h is both the height (m) of the wall above the line drawn from the observer to the geometric centre, and
the horizontal length of the wall in both directions from a point opposite to the geometric centre at
distance R.
With known values for R and the decibel reduction desired, a specific value of h can be calculated.
Whenever sound is reflected by a wall, the original wave and its reflection combine to form standing
waves. In order to limit the increased sound level that can result from these standing waves, the wall
should be placed at odd multiples of a quarter wavelength of the 120 Hz sound being attenuated away
from the transformer tank wall. Wall placements at multiples of a half wavelength should be avoided.
In addition to selecting the proper spacing to eliminate standing waves, it is necessary to absorb the
sound at the inner surface of the barrier to obtain the best results. Tests have shown that even with
proper wall spacing, a hard surfaced wall can result in a noise increase of 1–3 dB. Specially designed
sound absorbing masonry blocks with cavities resonant at 120 Hz can also be effective.
If it is desired to control the sound in one direction, a two- or three-sided barrier can be used. Model
tests have shown that predictable attenuation can be obtained over a 90° sector (see Figure 2). Outside
the 90° sector, attenuation is somewhat lower, and the noise radiated to the unshielded regions can
increase. Two- or three-sided barriers can be used when there is little chance of a complaint coming
from the open side of the barrier. The location of nearby control houses and other large surfaces should
also be noted as they can act as a reflective surface and increase the sound level in the opposite
direction. Four -sided barriers can be used with predictable results only if the inside surfaces are lined
with a good absorbing material to prevent multiple reflections. If greater attenuation is required, a
partial roof can be constructed. As the barrier becomes more complete, however, transformer cooling
can become a problem. This may make it necessary to derate or modify the transformer to add more
fans, or admit air through the bottom of the wall through sound-absorbing ducts. Another alternative
for forced oil and air (FOA) transformers is to mount coolers with low-noise fans outside the sound
enclosure using extended piping and vibration isolators.

<br>
<br>

Figure 2— Regions of sound attenuation and sound increase around (a) L-shaped barrier (two-
sided) and (b) U-shaped barrier (three-sided) [from IEEE std 1127-1998(R2004)]
4.3.4.8 Active noise cancellation techniques
Another solution to the problem of transformer noise involves use of active noise control technology to
cancel unwanted noise at the source, and is based on advances in digital controller computer
technology. Active noise cancellation systems can be tuned to specific problem frequencies or bands of
frequencies achieving noise reduction of up to 20 dB.

<br>
<br>
4.3.5 Community acceptance

<br>
<br>

The noise level at which transformers become an annoyance is not necessarily dependent upon the
level of the transformer noise but may depend upon the differential between ambient and added noise.
If the transformer can be heard, it can be an annoyance. Information from the noise profile study may
be used for a presentation to obtain community acceptance.
Noise attenuation with distance is logarithmic, and even where large buffer zones exist, the noise levels
from larger transformers can exceed 25–30 dBA at 300 m or more. In quiet rural areas, and some
suburban areas, low night time ambient sound levels of 30 dBA or less are possible. The higher
background ambient noise levels resulting from high traffic volume, business and industrial activity,
and the normal household activities such as children playing, dogs barking, lawn mowing, etc., will be
missing during the evening and night time hours. On warm summer nights, nearby residents can find
the transformer noise level to be annoying (for sleeping with open windows, sitting outside, etc.). As a
result, sound levels well below the ones imposed by governmental regulations may have to be
considered to lessen complaints.
Objections to substation noise levels below those set by governmental regulations can also occur in
urban areas. However, the benefit resulting from higher ambient background levels of 35–45 dBA or
more (night time) can be offset by the closer proximity of nearby residents [in some cases less that 30
m]. Community acceptance of noise levels may not always have a technical basis. Residents who are
annoyed simply by the presence of the substation may find perceived excessive noise levels to be a
tangible factor upon which to base a complaint.
4.4 Electric and magnetic fields
Electric substations produce electric and magnetic fields. These power frequency electric and magnetic
fields are a natural consequence of electrical circuits and are found around appliances and machines in
the home and workplace. They can be either calculated or directly measured. Governmental regulations
concerning levels may exist, and where they do, the substation design must comply.
In a substation, the strongest fields around the perimeter fence come from the transmission and
distribution lines entering and leaving the substation. The strength of fields from equipment inside the
fence decreases rapidly with distance, reaching very low levels at relatively short distances beyond
substation fences.
There has been substantial interest by the public and the scientific community in the question of
whether the exposure to these fields involves a risk to humans or the environment. Worldwide, the
many epidemiological, engineering, and biological studies of the effects and risks of EMF on people
have been inconclusive in their results and for many the questions on the health risks remain
unanswered.
In response to the public concerns with respect to EMF levels, whether perceived or real, and to
governmental regulations, the substation designer may consider design measures to lower EMF levels
or public exposure to fields while maintaining safe and reliable electric service.

<br>
<br>

4.4.1 Electric and magnetic field sources in a substation

<br>
<br>

Typical sources of electric and magnetic fields in substations include the following:
a) Transmission and distribution lines entering and exiting the substation;
b) Bus work;
c) Transformers;
d) Air core reactors;
e) Switchgear and cabling;
f) Line traps;
g) Circuit breakers;
h) Earth mesh or Ground grid;
i) Capacitors;
j) Battery chargers;
k) Computers;
l) Generators;
4.4.2 Electric fields

<br>
<br>

Electric fields are present whenever voltage exists on a conductor. Electric fields are not dependent on
the current. The magnitude of the electric field is a function of the operating voltage and decreases with
the square of the distance from the source. The strength of an electric field is measured in volts per
meter. The most common unit for this application is kilovolts per meter. The electric field can be easily
shielded (the strength can be reduced) by any conducting surface such as trees, fences, walls, buildings
and most structures.

<br>
<br>

In substations, the electric field is extremely variable due to the screening effect provided by the
presence of the earthed or grounded steel structures used for electric bus and equipment support.
Although the level of the electric fields could reach magnitudes of approximately 13 kV/m in the
immediate vicinity of high -voltage apparatus, it decreases significantly toward the fence line. At the
fence line, the level of the electric field approaches zero kV/m. If the incoming or outgoing lines are
underground, the level of the electric field at the point of crossing the fence is negligible. Since the
scope of this guide is community acceptance, this guide does not cover occupational guidelines.

<br>
<br>4.4.2.1 Governmental regulations
<br>
<br>


The Electrical Safety code ZS 418 specifies guidelines for safe distances from live conductors for
different voltage levels at 50 Hz.

<br>
<br>

4.4.2.2 Reduction methods

<br>
<br>

Reduction techniques that may be available to the substation designers are as follows:
a) Increase the height of the buses. If the height of buses doubles, the level of electric field directly
underneath the bus decreases by more than 50%; however, this may cause only a negligible decrease of
the electric field strength at the substation property line.
b) Decrease the phase spacing and bus diameter. Theoretically, a decrease of 50% of either phase
spacing or bus diameter could cause a reduction in the electric field level by approximately 10%.
Allowable phase spacing reduction may be limited by other factors such as electrical clearances and
short-circuit forces. Some phasing arrangement on parallel circuits, such as phase 1-2-3 on one circuit
and phase 3-2-1 on the other circuit, will result in increasing the field level because the fields of the
adjacent number 3 phases add together.
c) Lower operating system voltage. The effects of electric field depends on how high the system
voltage is.
d) Optimise substation layout. The presence of nearby buses, either earthed (grounded) or at lower
voltages acts as a shield and reduces the electric field in the immediatearea.
e) Use natural shielding. Trees and other vegetation along the property line may reduce the electric
field level there.

<br>
<br>

4.4.2.3 Community acceptance

<br>
<br>

Community acceptance of a project’s electric field levels can be improved by open, direct, and honest
communication of the electric field design to the affected public. By clearly and plainly demonstrating
the definition and design levels of electric fields, an informed consensus can be reached.

<br>
<br>

4.4.3 Magnetic fields

<br>
<br>

Magnetic fields are present whenever current flows in a conductor, and are not voltage dependent. The
level of these fields also decreases with distance from the source but these fields are not easily
shielded. Unlike electric fields, conducting materials such as the earth (ground), or most metals, have
little shielding effect on magnetic fields.
Magnetic fields are measured in Webers per square metre (Wb/m
2
) or Tesla. Various factors affect the
levels of the fields, including the following:
a) Current magnitude;
b) Phase spacing;
c) Bus height;
d) Phase configurations;
e) Distance from the source;
f) Phase unbalance (magnitude and angle).

<br>
<br>

Magnetic fields decrease with increasing distance (r) from the source. The rate is an inverse function
and is dependent on the type of source. For point sources such as motors and reactors, the function is
1/
3
r
; for three-phase, balanced conductors the function is 1/r
2
; and for single-phase sources such as
neutral or ground conductors the function is 1/r. Besides distance, conductor spacing and phase balance
have the largest effect on the magnetic field level because they control the rate at which the field
changes.
Magnetic fields can sometimes be shielded by specially engineered enclosures. The application of these
shielding techniques in a power system environment is minimal because of the substantial costs
involved and the difficulty of obtaining practical designs.

<br>
<br>
4.4.3.1 Magnetic field measurements
Measurements can be made using a commercially available, three-axis recording magnetic field meter.
Measurements should be made as a minimum at the property line. Additional measurements could be
taken at appropriate locations such as the substation fence line. The two basic measurement types are as
follows:
?
Snapshot. Survey of magnetic field levels made at one instant in time;
? Timed. Snapshots made over a daily or weekly load cycle.
Measurements should be made to establish ambient levels at new sites, determine baseline levels at
existing sites, or to verify calculated values.
Results can be presented as follows:
a) Line graphs showing magnetic field levels versus linear distance along fence or property lines.
Sources of peak field levels should be identified where possible. These are usually due to overhead
and/or underground power lines into or out of the substation.
b) Contour plots showing magnetic field levels as contour lines on a site plan. The location of
major site facilities such as buses, transformers, control house, fence, roads, and overhead and/or
underground lines should be shown.
c) Three-dimensional plot of magnetic field levels on a site plan.
4.4.3.2 Magnetic field calculation methods
Should it be necessary to calculate the field levels within the station, it should be recognised that this
could be complex and it is recommended that commercially available computer programs be used.
Several computer programs are available that utilise a simplified representation of the substation to
model and vary the magnetic field levels in and around a substation. The model typically includes the
high-voltage buses and conductors and the last one or two spans of the transmission and distribution
lines into or out of the substation. It is important to accurately model the phase relationship of the
substation conductors and the lines. It is recognised that the relative position of the phase conductors
may not be known when all three conductors are installed in a common duct. The phase arrangement
assumed in this circumstance shall be chosen by analyzing many possible combinatio ns of conductors
in the duct bank and selecting one that results in magnetic field levels greater than the median field
levels of the combinations evaluated.
The following are some common assumptions that could be considered; however, actual conditions
may change the results:
a) Loads include peak loads or transformer nameplate loads.
b) Transmission and distribution circuits have balanced loads. Neutral and earth or ground
currents are usually not considered.
c) Substation is in its normal operating stat e with regard to breaker and switch positions and
equipment in service.
d) Equipment such as high -voltage circuit breakers, switches, transformers, switchgear, control
cables, and low voltage power cables are typically not modelled.

<br>
<br>

In evaluating the results, modifications should be considered when the substation designer has specific
regulation criteria or governmental guidelines for magnetic field reduction. Utilities may be directed by
the Energy Regulation Board to take EMF reduction steps on transmiss ion, substation, and distribution
facilities to reduce exposure to magnetic fields. This criterion is generally intended to be applied to new
construction where design changes can be made with little or no increase in the cost of the substation.

<br>
<br>

4.4.3.3 Governmental regulation

<br>
<br>

There are no governmental regulations specifically for power frequency magnetic fields in substations
in Zambia
Magnetic field levels at substations are lower at the substation fence than at the edge of the right-of-
way. The highest magnetic field levels will most often be found directly underneath the overhead lines
or above the underground lines entering or exiting the substations. The magnetic field levels produced
by the substation itself are lower because of the buffer zone present between the substation equipment
and the fence line.

<br>
<br>

4.4.3.4 Reduction methods

<br>
<br>

Reduction techniques that may be available to the substation designer include the following:
a) Increase the distance from the sources. The substation designer shall choose the area of interest
for reduction and the distance to be increased. One method is to consider the areas that are
accessible to the public. Limiting public access to the areas with the lowest fields may involve
moving the substation security fence, increasing the height of incoming transmission lines, or
moving the outgoing distribution lines or duct banks to another location inside the substation.
Another method of increasing distance is locating substations close to or on existing transmission
corridors.
b) Reduce conductor spacing to increase the phase-to-phase cancellation of the magnetic fields,
resulting in a reduction of the total magnetic field strength. Installing substation feeder outlets in
underground ducts allows the phases to be placed in a single duct, thus reducing the overall
magnetic field strength.
c) Minimise currents by increasing operating system voltages, minimising power transfers,
providing reactive load compensation, and/or providing alternate transmission line power flow
paths.
d) Balance currents on transmission/distribution lines.
e) Optimise phase configuration to achieve magnetic field cancellation by choosing a bus design
with phase configuration of vertical, delta, or a combination of both rather than a horizontal
design.
f) Shield the source by surrounding the conductors, primarily buses, with a shield structure.

<br>
<br>

4.4.3.5 Community acceptance

<br>
<br>

In many communities EMF is perceived as an unacceptable risk affecting the health, property values,
and the environment of the community. Unsatisfactory resolution of these concerns by the project team
or the utility can evolve into project delays or changes, legal issues, and the possibility of the project
being stopped or cancelled.
To obtain permits, the project team may be required to involve the community and provide the public
and the Energy Regulation Board with data explaining the design and levels of magnetic fields created
by the project. If project management determines to resolve EMF concerns in the community by
involving the public, it is important to work openly and honestly with the community. Great care must
be taken not to mislead the community regarding magnetic field levels.
To obtain a community’s consensus and acceptance, the project team should prepare a plan for
involving the community and strive to develop a positive relationship of trust and credibility within the
community by listening and acknowledging their right to be concerned about matters that affect them.

<br>
<br>

Community acceptance of EMF levels may not always have a technical basis. Residents who are
annoyed simply by the presence of the substation may find perceived excessive EMF levels to be a
tangible factor upon which to base a complaint.

<br>4.5 Safety and security

<br>4.5.1 Fences and walls
The primary means of ensuring public safety at substations is by the erection of a suitable barrier, such
as a fence or a wall with warning signs. As a minimum, the barrier should meet the requirements of the
electrical safety code.
Recommended clearances from substation live parts to the fence and security methods are specified in
the Electrical Safety Code ZS 418.
4.5.2 Lighting
Yard lighting may be used to enhance security and allow equipment status inspections. A yard-lighting
system should provide adequate ground-level lighting intensity around equipment and the control-
house area for security purposes without disruption to the surrounding community. High levels of
nightly illumination will often result in complaints.
4.5.3 Earthing or grounding
Earthing or grounding should meet the requirements of ZS691 to ensure the design of a safe and
adequate earthing or grounding system. All non-current-carrying metal objects in or exiting from
substations should be earthed (grounded), generally to a buried metallic grid (mesh), to eliminate the
possibility of unsafe touch or step potentials, which the general public might experience during fault
conditions.
4.5.4 Fire protection
The potential for fires exists throughout all substations. Although not a common occurrence, substation
fires are an important concern because of potential for long-term outages, personnel injury or death,
extensive property and environmental damage, and rapid uncontrolled spreading. Refer to ZS692 for
detailed guidance and identification of accepted substation fire-protection design practices and
applicable industry standards.

<br>
<br>5. PERMITTING PROCESS

<br>
<br>A variety of permits may be required by the governmental regulatory bodies before construction of a
substation may begin. For the permitting process to be successful, the impact on the community and the
environment of the following factors may have to be considered:
<br>
a) Site location;
<br>
b) Level of ground water;
<br>
c) Location of wetlands;
<br>
d) Possibility of existing hazardous materials;
<br>
e) Need for potable water and sewage;
<br>
f) Possible noise;
<br>
g) Aesthetics;
<br>
h) EMF; and
<br>
i) Information and communication technologies (ICT).
<br>
<br>
Timing for the permit application is a critical factor because the permit application may trigger
opposition involvement. If it is determined that the situation requires public involvement, the
preparation and implementation of a detailed plan using public participation can reduce the delays and
costs associated with political controversy and litigation. In these situations, public involvement prior
to permit application can help to build a positive relationship with those affected by the project,

identify political and community concerns, obtain an informed consensus from project stakeholders,
and provide a basis for the utility to increase its credibility and reputation as a good neighbour.
Examples of approaches that have been used with success are described in 5.1 and 5.2 to aid those
responsible for cost efficiency and on-time completion and those who secure the various construction
permits.

<br>
<br>5.1 Active community involvement
Public participation can be defined as the process by which a utility consults with interested or affected
individuals, organisations, and government entities before permit applications are filed. Active
community involvement is often based on the premise that if the community is presented with the facts
and given the opportunity to have their questions answered, informed consensus will be reached and
opposition (based on the fear of the unknown) to the project will fade. This approach seeks out the
public’s thoughts, concerns, fears, and opinions before decisions are made.
Public participation differs from public relations or public information programs where information
flows only outward from the utility by providing two-way communication and collaborative problem
solving with the goal of achieving better and more acceptable decisions. Every effective public
participation programme does however, include a public information component. Public participation is
mutual problem solving between the community and the utility in an effort to reach a decision that
achieves public acceptance. An exchange of information takes place, but, beyond that, public
participation is an effort to find an acceptable solution. In order to reach an informed consensus, the
information presented to the public must be complete and objective.
<br>
<br>
Common goals of a public participation plan are as follows:
<br>
a) Informing the public;
b) Information gathering;
c) Identifying public concerns and values;
d) Developing a consensus;
e) Achieving acceptance;
f) Developing and maintaining credibility.
<br>
<br>
Some governmental regulatory bodies may require public participation prior to the permit application.
<br>
<br>
5.2 Low-key community involvement
<br>
<br>

Low-key community involvement can be defined as the process by which a utility consults with
interested or affected individuals and public organisations only after permit applications are filed. In
this situation, the project’s plan for public participation would indicate that a low-key community
involvement approach will be successful where communication is limited initially to the immediate
governmental officials and decision makers. Extensive involvement of the public would be pursued
only as requested during the permitting process as the need develops.

<br>
<br>

This approach can be successful in situations where there are no governmental regulations or
guidelines requiring upfront public involvement, and where no strong opposition exist in the project
area. The organised opposition that can arise from public involvement can override any attempt at open
communications. This may be especially true where the real focus of the media and/or opposition has
little direct correlation with the specific substation project, but rather uses the project simply as a
convenient rallying point for some other agenda.

<br>
<br>

6. CONSTRUCTION

<br>
<br>6.1 Site preparation

<br>
<br>The site preparation process includes a number of activities that could have potential impact on the
community acceptance and the environment. The following is a listing of these activities, the problems
presented, and the control methods available. All construction work should be done in accordance with
the pre-agreed project plan.

<br>
<br>6.1.1 Clearing, grubbing, excavation, and grading

<br>
<br>Concerns include the creation of dust, mud, water runoff, erosion, degraded water quality, and
sedimentation. The stockpiling of excavated material and the disposal of excess soil, timber, brush,
etc., are additional items that should be considered. Protective measures established during the design
phase or committed to through the permitting process for ground water, wetlands, flood plains, streams,
archaeological sites, and endangered flora and fauna should be implemented during this period.

<br>
<br>6.1.2 Site access roads

<br>
<br>The preparation and usage of site access roads create concerns that include construction equipment
traffic, dust, mud, water runoff, erosion, degraded water quality, and sedimentation. Access roads can
also have an impact on agriculture, archaeological features, forest resources, wildlife, and vegetation.

<br>
<br>6.1.3 Water drainage
<br>
<br>
Runoff control is especially important during the construction process. Potential problems include
flooding, erosion, sedimentation, and waste and trash carried off site.

<br>
<br>6.1.4 Control methods

<br>
<br>The following is a listing of methods that can be used to prevent or control problems:
a) Dust and mud control:
<br>
<br>
1) Water sprinkling trucks and spray hoses;
<br>
2) Chemical—non toxic dust retarders;
<br>
3) Timely operation—in cases of moving equipment;
<br>
4) Covered haulers;
<br>
5) Crushed stone access road;
<br>
6) Vehicle washing;
<br>
7) Routine road cleanup.
<br>
b) Erosion and sedimentation control:
<br>
1) Silt fences and hay bales;
<br>
2) Sediment basins and ponds;
<br>
3) Terracing, benching, and serrated slope areas;
<br>
4) Stone and soil dikes;
<br>
5) Drainage ditches;
<br>
6) Diversion structures;
<br>
7) Vegetation buffers;
<br>
8) Soil stabilisation (seeding, netting, vegetation binders, wood chip cover, mulching, sodding, hay
or straw matting, shrubbery, and creeper planting);
<br>
9) Site access roads should follow natural site contours where possible.
<br>
<br>
6.2 Noise
<br>
<br>
Noise control is important during construction in areas sensitive to this type of disturbance. An
evaluation should be made prior to the start of construction to determine noise restrictions that may be
imposed at the construction site. Typical areas where noise mitigation controls may be required include
residential, hospital, convalescent home, office, school, and wildlife sanctuary.
The following are suggested methods that can be used to reduce noise during the construction process:
<br>
<br>
a) Equipment mufflers;
<br>
b) Barrier walls;
<br>
c) Blasting mats;
<br>
d) Sound-absorbent materials;
<br>
<br>

<br>
e) Selective and timely use of equipment (e.g., avoid weekend, late evening, and early morning hours).
<br>
<br>
6.3 Safety and security
<br>
<br>


Problems associated with an undeveloped property can occur during the construction stage of a
substation and should be considered. In fact, the presence of construction materials and equipment can
create additional attractive nuisances. New hazards such as excavations, uncompleted structures, and
construction equipment now are on site that could cause injury to unauthorised personnel or even
passers by.
Safety and security procedures should be implemented at the outset of the construction process to
protect the public and prevent unauthorised access to the site. These procedures should be developed in
conformance with regulations such as the Factories Act Cap 441; Refer to appendix 1. The safety and
security programme should be monitored continuously to ensure that it is functioning properly.
The following are suggestions for safety and security at the site:

<br>
<br>a) Temporary or permanent fencing;
<br>
b) Security guards;
<br>
c) Security monitoring systems ;
<br>
d) Traffic control;
<br>
e) Warning signs;
<br>
f) Construction safety procedures;
<br>
g) Temporary lighting.
<br>
<br>
6.4 Traffic control
<br>
<br>


The use of various types of construction vehicles and greater presence and flow of personal vehicles
are experienced during the construction period than when the substation is in normal operation.
To minimise the impact on the substation neighbourhood, the following should be considered:

<br>
<br>
a) Police assistance and manual traffic control;
<br>
b) Traffic signal installations;
<br>
c) Reduce traffic at peak hours of commercial or community use;
<br>
d) Coordinate movement with industries, schools, or other activities in the area;
<br>
e) Move oversized vehicle loads over roadways during minimum traffic periods;
<br>
f) Provide adequate parking on site.
<br>
<br>
6.5 Site housekeeping
<br>
<br>


During construction, debris and refuse should not be allowed to accumulate. Efforts should be made to
properly store, remove, and prevent these materials from migrating beyond the construction site.
Burning of refuse should only be done in an approved manner. In open areas this activity is prohibited
by the Environmental Protection and Pollution Control Act Cap 204.
Portable toilets that are routinely serviced should be provided.

<br>
<br>

6.6 Hazardous material

<br>
<br>

The spillage of transformer and pipe cable insulating oils, paints, solvents, acids, fuels, and other
similar materials can be detrimental to the environment as well as a disturbance to the neighbourhood.
Proper care should be taken in the storage and handling of such materials during construction.

<br>
<br>

There are many substances which, if found on a substation site during construction, will require
stoppage of work and notification of Environmental Council of Zambia before the site can become
usable. Some such substances are PCBs, asbestos, dioxin, lead and other heavy metals, and radioactive
materials. Equipment containing unacceptable chemicals should not be utilised in new constructions.
Disposal of hazardous materials should be done with care, avoiding spills and adhering to appropriate
guidelines, procedures, and governmental regulations.

<br>
<br>

7. OPERATIONS

<br>
<br>

7.1 Site housekeeping

<br>

<br>7.1.1 Water and sediment control

<br>
<br>

Routine inspection of controls for water flows is important to maintain proper sediment control
measures. Inspection should be made for basin failure and for gullies in all slopes. Inspection of all
control measures is necessary to be sure that problems are corrected as they develop, and should be
made a part of regular substation inspection and maintenance.

<br>
<br>

7.1.2 Yard surface maintenance

<br>
<br>

Yard surfacing should be maintained as designed, to prevent water runoffs and control dust. If
unwanted vegetation is observed on the substation site, approved herbicides may be used with caution
to prevent runoff from damaging surrounding vegetation. If runoffs occur, the affected area should be
covered with stone to retard water runoff and to control dust.

<br>
<br>

7.1.3 Paint

<br>
<br>

When material surfaces are protected by paint, a regular inspection and repainting should be performed
to maintain a neat appearance and to prevent corrosion damage. The colour can be maintained by
taking the steps outlined in section 4.2.4

<br>
<br>
7.1.4 Landscaping

<br>
<br>

Landscaping should be maintained to ensure perpetuation of design integrity and intent. Successful
accomplishment of this goal will be enhanced by
<br>
a) Watering;
<br>
b) Fertilisation;
<br>
c) Approved chemical application;
<br>
d) Pruning and vegetation control;
<br>
e) Lawn maintenance;
<br>
f) Plant replacement as needed.
<br>
<br>
7.1.5 Storage
<br>
<br>
In some areas, zoning will not permit storage in substations. The local zoning must therefore be
reviewed before storing equipment, supplies, etc. The appearance of the substation site should be
considered so it will not become visually offensive to the surrounding community.
<br>
<br>
7.2 Noise
<br>
<br>
Inspection of all attributes of equipment designed to limit noise should be performed periodically.
<br>
<br>
7.2.1 Continuous audible sources
<br>
<br>
Periodic maintenance and inspection of station equipment and systems should be performed to ensure
that they are functioning in accordance with their design. Any loose attachments resulting from
vibration could add to continuous noise levels produced by the substation and should be corrected.

<br>
<br>


Inspections of connector hardware and bus for proper installation and follow-up removal of rough
edges, projections, and rough surfaces might be required to ensure continuous corona-free
performance, and to minimise Radio Frequency (RF) noise. It is also important to maintain good
electrical contact in all metallic parts to eliminate gap sparking by ensuring proper contact pressures.

<br>
<br>7.2.2 Impulse source

<br>
<br>

Community disturbances from circuit-breaker (especially air-blast type) and switch operations can be
minimised by proper scheduling of equipment maintenance and testing.

<br>
<br>
7.3 Safety and security

<br>
<br>

All substations should be inspected regularly, following established and written procedures to ensure
the safety and security of the station. Safe and secure operation of the substation requires adequate
knowledge and proper use of each company’s accident prevention manual. See Appendix 1.
Routine inspections of the substation should be performed and recorded, and may include the
following:

<br>a) Fences;

<br>b) Gates;

<br>c) Padlocks;
d) Signs;
<br>
e) Access detection systems;
<br>
f) Alarm systems;
<br>
g) Lighting systems;
<br>
h) Earthingor grounding systems;
<br>
i) Fire protection equipment;
<br>
j) All oil-filled equipment;
<br>
k) Spill-containment systems.
<br>
1) Gas -filled and vacuum equipment
<br>
<br>
7.4 Fire protection
<br>
<br>


Refer to ZS 692 for detailed guidance and identification of accepted substation fire-protection practices
and applicable industry standards. Any fire-protection prevention system installed in the substation
should be properly maintained.
<br>
<br>


7.5 Hazardous material
<br>
<br>
A spill-prevention control and counter-measures plan should be in place for the substation site and
should meet ECZ requirements. For general guidance involving other materials see ECZ guidelines.

<br>
<br>


APPENDIX 1: Guide for Electric Power Substation Physical and Electronic
<br>
<br>

Security

<br>
<br>
This appendix is based on IEEE Std 1402-2000.

<br>
1. SCOPE AND PURPOSE
<br>
<br>
1.1 Scope
<br>
<br>
This appendix identifies and discusses security issues related to human intervention during the
construction, operation (except for natural disasters), and maintenance of electric power supply
substations. It also documents methods and d esigns to mitigate intrusions.
<br>
<br>
1.2 Purpose
<br>
<br>
Access to electric supply substations by unauthorised personnel is an increasing problem for the
electric industry. These intrusions may result in loss, damage, and maloperation of equipment and
facilities and m ay create potential safety and environmental liabilities. This appendix presents various
methods and techniques presently being used to mitigate human intrusions, as identified in an industry
survey. In 1994, an IEEE Substation Security Guide Survey questionnaire was sent to utilities
internationally; the responses from this survey are presented in Clause 7 of this appendix..
<br>
<br>
3. Definitions
<br>
<br>
Definitions of terms pertinent to the subject matter are listed here. Definitions as given herein apply
specifically to the application of this appendix. For additional definitions, see IEEE 100 -1996.
<br>
<br>
3.1 construction stage:
<br>
<br>
The time related to the installation or modification of fixtures or structures, including services,
foundations, steel, conductors, buildings, and earthing or grounding.
<br>
<br>
3.2 intrusion:
<br>
<br>
Unauthorised access to the substation property through physical presence or external influence.
<br>
<br>
3.3 operational stage:
<br>
<br>
The time following commissioning of the facility.
<br>
<br>
3.4 undeveloped stage:
<br>
<br>
The time prior to the installation of permanent structures, site preparation, preliminary surveying,
surface stripping, fence erection, road building, equipment and material staging, furnishing
construction power, etc.
<br>
<br>
4. Intrusions
<br>
<br>
4.1 Types of intrusions
<br>
<br>
Intrusions can be classified into the following categories:
<br>
<br>
a) Pedestrian: A person walking onto the substation property or into the substation proper, either
accidentally or for the purpose of vandalism, robbery, theft, dumping, or other illicit activities.
b) Vehicular: A vehicle driven into a substation, either through an open gate or through the perimeter
fence or wall. This intrusion may be for the same purposes listed in item a), or may be the result of an
accident.

<br>
<br>
c) Projectile: Foreign objects thrown or propelled into the substation area that may damage substation
equipment or the control room (e.g., rocks, kites, bottles, missiles, explosives, and bullets).
<br>
<br>
d) Electronic: Entry into the substation via telephone lines or other electronic-based media for the
manipulation or disturbance of electronic devices. These devices include digital relays, fault recorders,
equipment diagnostic packages, automation equipment, computers, programmable logic controllers,
and communication interfaces.
<br>
<br>
4.2 Parameters and events that influence intrusions
<br>
4.2.1 Economic
In some areas, theft of copper, aluminum, or other components from a substation may be prevalent.
<br>
<br>
4.2.2 Location
Higher levels of crime, vandalism, and graffiti may be common behaviours in certain neighbourhoods.
School properties or other public areas adjacent to or near a substation or substations located in remote
areas may also present additional opportunities for intrusions.
<br>
<br>
4.2.3 Aesthetics
Walls, plantings, or screening treatments may make substations an attractive and secluded meeting spot
for various recreational or illicit activities.
<br>
<br>
4.2.4 Labour conflicts
Strikes, slowdowns, personnel reductions, or other labour conflicts by utility or contract workers can be
a significant factor influencing intrusions as the substation can be an attractive target.
<br>
<br>
4.2.5 Use of adjacent property
<br>
Uses of adjacent property may lead to intrusions onto substation property. Commercial activities,
building, storage, equipment and material locations, and building structures can facilitate intrusions
onto substation property.
<br>
<br>
4.2.6 Curiosity and ignorance
<br>
Many items in a substation may attract curious individuals who are unaware of the hazards that exist
within the substation fence.
<br>
<br>
4.2.7 Civil/political unrest
<br>
<br>
Terrorism, war, riots, civil disobedience, and public events provide increased opportunity for
intrusions.
<br>
<br>
4.2.8 Joint-use facilities
<br>
<br>
Establishment of a substation on or adjacent to a facility that is shared, owned, or used by others could
provide additional opportunity for intrusions as the potential for legitimate access by unqualified
personnel increases.
<br>
<br>
4.2.9 Natural and/or catastrophic disasters
<br>
<br>
The effects of natural and/or catastrophic disasters may render security systems ineffective.
<br>
<br>
4.3 Problems caused by intrusions
<br>
<br>
Human intrusions onto substation sites can create many problems and can occur during any of the
following three stages of substation development:


<br>
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a) The undeveloped stage
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b) The construction stage
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c) The operational stage
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These problems, which can be unique to only one stage or can be common to one or more of the three
stages, are discussed in clauses 4.3.1, 4.3.2, and 4.3.3 of this appendix.
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4.3.1 Undeveloped stage
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This appendix assumes that at the time a substation property is obtained, it is free of any hazardous
materials.
The problems associated with an undeveloped substation property can generally be classified as
attractive nuisances, dumping, vandalism, illicit activities, and sabotage.
Attractive nuisances are any items that, by their mere presence, may draw people’s attention for use or
play without recognis ing their dangerous qualities. These may include, but are not limited to, old wells,
septic systems, caves, trees, rock formations, and ponds. These items may attract people onto the
property, where they may be injured or killed. Civil lawsuits could result from these occurrences.
An unsecured substation property is an attractive place for the dumping of trash or hazardous materials.
This dumping can cause public complaints or legal citations. The removal of these materials may be
quiteexpensive.
Vandalism on the property can create problems similar to those caused by dumping.
A vacant property may also provide a place for various unwanted or illicit activities to occur. These
activities may also cause public complaints and possible civil actions.
Finally, sabotage can be caused by disgruntled or striking employees, other personnel (e.g.,
construction crews, contracted services, customer utility manpower), or groups opposed to the
development of asubstation at the site.
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4.3.2 Construction stage
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Each problem associated with an undeveloped property and described above can occur during the
construction stage of a substation and should be considered. In fact, the presence of construction
materials and equipment can create additional attractive nuisances. New hazards such as excavations,
uncompleted structures, and construction equipment now are on site that could cause injury to
unauthorised personnel.
Additional problems that can occur during the construction stage are theft and increased vandalism.
Construction materials that contain copper and aluminum are very attractive since they can easily be
sold for scrap. The use of copper-clad or galvanised steel wire or stranded wire may be a theft deterrent
due to its negligible scrap value compared to solid copper wire or strand. During the construction stage,
these items are often packaged for convenient removal and may be stored in unsecured areas.
Construction equipment, such as pickup trucks and excavation equipment, is motorised and can be
easily removed from the site. The removal or vandalism of materials and equipment will increase the
cost of the project. In addition, many of the items required for the construction of a substation have
long delivery times and are not easily replaced. The loss of these items may also drastically delay the
completion of the project and increase cost.
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4.3.3 Operational stage
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Although the substation is normally energised during the operational stage, nearly all of the potential
problems described above, as well as the removal of gauges and copper ground materials, meter
damage, and the opening of transformer valves, can occur. The fact that a substation is energis ed does
not deter theseproblems.

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An additional concern during the operational stage arises from the fact that the substation is normally
energised and often unattended. At this stage, intrusions can affect the integrity of the electric power
supply and the reliability of the transmission and distribution grid, if the intrusion results in power
interruptions. Examples include projectiles, poles, or kites that come in contact with energised parts,
and electronic interference with relaying and control circuits. Intruders have been kn own to open
valves, push buttons, and operate circuit breakers, reclosers, and switches.
Another area of concern comes from employees and other authorised personnel with legitimate access
to a substation. Their actions can defeat the security aspects of t he station design in order to facilitate
their functions, such as removal of a vehicle gate centre stay to allow easier removal of waste. Such
actions may allow a locked gate to move beyond its design limits and permit unauthorised access.
Sabotage becomes more of a concern in the operational stage. Sabotage can be done by those who
normally have legitimate access to the substation, such as construction crews, contracted services,
customer or utility manpower, or by those with no legitimate access, such as criminals, activists, and
extremists.
Safety concerns increase significantly because of the potential for accidental human contact with
energised equipment or removal of earthing or grounding material that could cause hazardous