Development of Noise Testing Equipment and Noise Withstand Capability Tests for Existing Protective Relays

With a view to making a precise analysis on operation of protective relays in power systems for noise, a new noise testing equipment has been developed and installed for trial, which is capable of generating a wide band of noise with frequencies ranging from 1 kHz to 2 MHz and also of controlling conditions under which the noise is applied. A series of noise withstand capability tests were conducted with the aid of this testing equipment for some existing static relays. This paper deals with firstly the specifications and some features of the testing equipment and, secondly some findings on the noise withstand capability of protective relays through the test results.