Oil filter unit for power transformer stepping switch with regulation of feed pump motor for maintaining required volumetric flow rate through filter unit

摘要

The oil filter unit is supplied with oil via a feed line (9) and has a feed pump driven by a pump motor followed by a filter capsule, with a feedback line (4) for returning filtered oil back to the stepping switch (7). The feed line contains a measuring device for the volumetric flow, e.g. a calorimetric flow sensor (10), supplying an electrical signal to a regulator providing a setting signal for the pump motor by comparing the actual volumetric flow with a required value.