Classification parameters Transformers can be classified in many ways, such as the following: Power capacity: From a fraction of a volt-ampere (VA) to over a thousand MVA. Duty of a transformer: Continuous, short-time, intermittent, periodic, varying. Frequency range: Power-frequency, audio-frequency, or radio-frequency. Voltage class: From a few volts to hundreds of kilovolts. Cooling type: Dry and liquid-immersed - self-cooled, forced air-cooled; liquid-immersed - forced oil-cooled, water-cooled. Circuit application: Such as power supply, impedance matching, output voltage and current stabilizer or circuit isolation. Utilization: Pulse, power, distribution, rectifier, arc furnace, amplifier output, etc.. Basic magnetic form: Core form, shell form. Constant-potential transformer descriptor: Step-up, step-down, isolation. General winding configuration: By EIC vector group - various possible two-winding combinations of the phase designations delta, wye or star, and zigzag or interconnected star;[j] other - autotransformer, Scott-T, zigzag grounding transformer winding. Rectifier phase-shift winding configuration: 2-winding, 6-pulse; 3-winding, 12-pulse; . . . n-winding, [n-1]*6-pulse; polygon; etc.. Types A wide variety of transformer designs are used for different applications, though they share several common features. Important common transformer types include: Autotransformer: Transformer in which part of the winding is common to both primary and secondary circuits. Capacitor voltage transformer: Transformer in which capacitor divider is used to reduce high voltage before application to the primary winding. Distribution transformer, power transformer: International standards make a distinction in terms of distribution transformers being used to distribute energy from transmission lines and networks for local consumption and power transformers being used to transfer electric energy between the generator and distribution primary circuits. Phase angle regulating transformer: A specialised transformer used to control the flow of real power on three-phase electricity transmission networks. Scott-T transformer: Transformer used for phase transformation from three-phase to two-phase and vice versa. Polyphase transformer: Any transformer with more than one phase. Grounding transformer: Transformer used for grounding three-phase circuits to create a neutral in a three wire system, using a wye-delta transformer,[76][81] or more commonly, a zigzag grounding winding. Leakage transformer: Transformer that has loosely coupled windings. Resonant transformer: Transformer that uses resonance to generate a high secondary voltage. Audio transformer: Transformer used in audio equipment. Output transformer: Transformer used to match the output of a valve amplifier to its load. Instrument transformer: Potential or current transformer used to accurately and safely represent voltage, current or phase position of high voltage or high power circuits. |