Can On load tap changers cause Surge?

Answer 1

My experience with tap changers is in their use as voltage regulation devices. There are small ones used in laboratories and the electric company has some as big as a bus. In either case, the event of changing the tap has a consequence on the output. Electronic circuits that are a little cheap on the voltage regulation of their internal power supplies can see these tap changer "surprises" come through and create confusion. Some years ago I worked on debugging a computer system that always caved in in the early afternoon. Never an exact time, just sometime in the early afternoon. Cause was traced to a power company tap changer that was trying to hold the city voltage level constant as the air conditioners all came on.

How big a surge you get will depend on the size of the tap change.