Auto-transformer protection circuit testing method in which a test earth short circuit is formed in the multi-phase auto-transformer to enable checking of the operation of a current differential protection arrangement

摘要

Method for forming an earth short circuit in a multi-phase auto-transformer (20) with an earthed star point (22) so that an error signal (F) is generated by a current differential protection arrangement (24). An Independent claim is made for a current differential protection arrangement for a multi-phase auto-transformer in which a star point transformer (26) is arranged between the star point and earth on the primary side and the current differential protection arrangement on the secondary side.