Current transformer error compensation - has auxiliary transformer in series with third winding to give accurate balance

摘要

An auxiliary transformer is connected with the secondary circuit in such a way that a balancing current is created in its primary winding which flows with secondary current in the load circuit. This partly compensates for error in the main transformer and also provides a defined over-current factor. To assist the fine adjustment of the compensation, a third winding is provided on the main transformer, arranged so that its own load includes the auxiliary transformer primary. A current flow in the primary winding is in the reverse direction to the main current in the secondary winding.