Internal voltage grading and transient voltage protection for power transformer windings.

摘要

A series string (17, 18) of plural zinc oxide varistor elements (17A-17N 18A-18N) is electrically connected across each winding (11, 12) of a power transformer. with interior winding tops (20, 22) being electrically connected to the junctions between varistor elements. Each varistor string, disposed within the transformer casing, protects its associated winding from voltage surges in the same manner as externally mounted lightning arresters, provides highly effective voltage grading, and suppresses harmful transient voltage oscillations between the winding taps.