There are two types of Tap changers in Transformers depending upon the rating of transformer.
- Off-load Tap changer
- On-Load Tap changer
If a tap-changer is designed to operate with the transformer out of circuit the it is called off-load tap changer. In that Transformer line should be disconnected completely before changing the tap.
If a Tap changer is designed to operate with the transformer in circuit then it is called as On-Load tap changer i.e. tap can be changed even when transformer will remains in line.
Read about about why and where tap changer required in Transformer:-
Let’s discuss here about off –load or No load Tap changer:-
No Load Tap Changer:-
This type of Tap changer is used for seasonal voltage variations as in Summers load on HT increases leads to drop in HT voltage so O/P can be increased by using Transformer Tap changer and in Winters when load get reduced HT voltage restores to normal levels then tap changer position can be done according to value of HT Voltage.
A tap changer is shown below:-
There are six studs marked as 1-6. The winding is tapped at six points equal to no. of studs. The tapping leads are connected to six corresponding marked stationary studs arranged in circle. The face plate carrying six studs can be mounted anywhere on Transformer. The Rotatable arm R can be rotated by means of Hand-wheel from outside transformer tank.