A PROTECTIVE RELAY-BASED MONITORING SYSTEM OF DC POWER WITHIN AN ELECTRIC POWER SUBSTATION

摘要

A DC monitoring system is provided in each protective relay in an electric power substation to detect DC grounds on the DC supply system. The DC monitoring system includes a first portion (62, 64) which indicates the presence of a DC ground. In a second portion of the system (76, 78), the voltages at the contact inputs of the relay are recognized and compared against a standard voltage value range. An indication is provided when the recognized voltage is within said range. The combination of the indications from the first and second portions is useful in determining the location of DC grounds in the substation DC supply system.