Tap changer for power transformer - has pole changing contact and auxiliary contact for maintaining connection with outgoing tapping winding until incoming one is bridged

摘要

The transformer tap changer operating with tapping windings giving positive and negative regulation by changing the phase of the tapping winding in relation to the main winding. The pole changing or polarity selector contact (16) carries an auxiliary contact link (18,19) When the selector moves from the positive pole to the negative the auxiliary contact maintains connection with the outgoing pole until contact between selector and incoming pole is established. With the arrangement, the regulating windings are never galvanically disconnected and cannot therefore take up a potential governed by capacitance coupling with other windings or leads. Auxiliary contacts (18,19,18',19') are provided at both ends of the selector (16). The auxiliary contacts may be spring operated to give a fast break.