What is a transformer tap changer?

A transformer tap changer is a mechanism that allows for variable turn ratios to be selected in distinct steps.

This is done by connecting to a number of access points known as taps along either the primary or secondary winding of the transformer.

By changing the turn ratio, the output voltage of the transformer can be regulated to the required level.

There are two main types of tap changers: no-load tap changers (NLTC) and on-load tap changers (OLTC).

NLTCs must be de-energized before the turn ratio is adjusted, while OLTCs can adjust their turn ratio during operation.

Tap changers can be either manual or automatic, depending on the application and the frequency of changing the turn ratio.