Analysis and treatment on the abnormalities of automatic stand-by power switching device

The device of automatic transfer to stand-by power supply(ATS) is widely used in electric power system.There are three operation modes for ATS,one is two power supply sources backing-up for each other,another is automatic transfer to stand-by transformer,and the third one is automatic transfer by bus tie breaker.Here,taking a fault treatment of automatic transfer circuit for the stand-by power supply of auxiliary power system in one thermal power plant's No.1 and No.2 units of Guangdong,6 kV and 380 V respectively,for the example,the important points and the problems needed to pay attention in maintenance and checking of ATS were investigated.