On-line condition monitoring system of medium-voltage switchgear

Switchgear is one of the key equipments of electrical power system. Its operation condition is very important for system reliability. Mechanical failure (open rejecting, close rejecting, and mechanical malfunction), insulation failure, and contacts overheating are in the majority of all operation failures. In this paper, an on-line condition monitoring system for 12kV switchgear is developed. In this system, the insulation condition of bushings, the temperature rise of the detachable contacts and the mechanical performance are detected on-line. For mechanical performance, the contact travel and the current of close and open release coils are detected. Thus the average speed and instant speed can be got from contact travel. A prototype of this on-line condition monitoring system has been developed. Experiments indicate that the monitoring system can perform accurate on-line detection of operation condition of switchgear, and it can offer exact forecasting in time.