Transformer differential safety systems.

摘要

A transformer differential safety system includes a plurality of active power measuring converter circuits (4), one for each phase winding of the transformer. An array of adding circuits (5) combine the outputs of these circuits with the output of a copper and iron loss calculating circuit (11) in such a manner as to generate an output signal related to the difference between the transformer input and output power. A comparison circuit (6) provides a tripping output when this output signal exceeds a set level.