Some different types of transformers are power transformers, potential transformers, audio transformers and output transformers. A transformer transfers electrical energy from one electrical circuit to another without changing its frequency. Transformers either decrease or increase AC voltage.
Power transformers are used in electric power transmissions and electrical appliances to convert main voltage to low voltage. There are two types of power transformers: laminated core and toroidal transformers. Laminated core transformers have an insulated lamination that minimizes eddy current loss in the inner core. Toroidal transformers have a lower external field and take up less space than the laminated core transformers.
Potential transformers are used to monitor single-phase and three-phase power line voltages in power metering applications. There are three types of potential transformers: optical, capacitor and electromagnetic transformers. Optical transformers are designed for optical materials. The electromagnetic and capacitor transformers are both designed for higher voltage applications.
Audio transformers are used to carry audio signals in audio circuits. They provide impedance matching between high and low impedance circuits. Audio transformers are commonly used to interconnect professional audio systems components.
Instrument transformers are used to operate instruments from high current circuits or high voltage lines. There are two types of instrument transformers: current and potential transformers. Current transformers are used with an ammeter to measure current in AC voltages, while potential transformers are used with a voltmeter to measure voltage in AC.