In electronic amplifier circuits, in order to minimize the transmission energy consumption between two amplifiers, impedance matching is required and connected to the transformer skeleton, which can change the impedance.

In an AC voltage regulator, the number of turns of the output coil is changed in real time to achieve the purpose of regulating the output voltage.

For remote input power lines, in order to reduce line losses, it is necessary to first increase the power of the power plant to tens of thousands of volts (such as 11KV), and then reduce it (such as 220V) after reaching the destination.

Sometimes, in an environment that requires different voltages, transformers can be made with multiple windings or center taps. This will generate various voltages.

When welding, a large current (tens to hundreds of amperes) is required between the electrode and the welded part, but the voltage is very small (a few volts). Welding machine is a transformer that converts high voltage (such as 220V) into low voltage. Generate high current at the output without changing the power.