Experimental Study on Vibration Characteristics of GIS Equipment under Typical Mechanical Defects

Mechanical vibration fault is one of the main causes of GIS equipment accidents. The current research mainly focuses on the vibration characteristics of GIS isolation switch under the defect of inadequate travel or the loose busbar, but there is still a lack of comprehensive comparison of the vibration characteristics of GIS equipment under different types of defects and different severity. Therefore, a 500kV GIS mechanical defect test platform was built in this paper to obtain GIS vibration characteristics of different types and severity of defects such as inadequate travel of isolation switch, loose busbar contact seat and loose shielding cover under different amplitude current injection. The test results show that under normal conditions, the vibration signal of GIS equipment shell is twice the frequency of the injection current, the amplitude is proportional to the square of the injection current, and the amplitude of the busbar gas chamber is higher than that of the isolation switch gas chamber. In the defect state, the vibration signal mainly shows the change of main frequency amplitude and high frequency harmonics. Using vibration signal characteristics, the isolation switch can be identified as normal state, spring loose defects, contact plate wear defects, contact not in place defects. And the busbar can be identified as normal state, loose defects of the contact seat, loose defects of the shielding cover, foreign body defects in the guide bar and loose defects of the support seat.