On-line condition monitoring system of medium-voltage switchgear

Switchgear is one of the key equipments of an 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 online condition monitoring system for 12 kV switchgear is developed. In this system, the insulation condition of bushings, the temperature rise of the detachable contacts and the mechanical performance are detected online. 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 obtained from contact travel. A prototype of this online condition monitoring system has been developed. Experiments indicate that the monitoring system can perform accurate online detection of the operation condition of switchgear, and it can offer exact forecasting in time.