A load tap changer system for electrical power transformers, including protective apparatus which prevents a tap change in the event of a malfunction during a tap change cycle. The protective apparatus includes a relay and a current responsive device for operating the relay when current is flowing at a location prior to a tap change which would not have current flow during a normal tap change cycle. Current applied to the relay is maintained within the operating range of the relay by a tapped transformer operated by the tap changer drive.

 
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