Abstract
Rationalization of the maintenance of gas-insulated equipment under operation and lifetime extension based on the results of appropriate diagnosis are necessary to reduce in the cost of gas-insulated equipment. Therefore, condition-based maintenance (CBM) is required and accurate methods for observing the inside of equipment is important. In this report, we describe a diagnosis method that can be used for actual gas-insulated equipment, such as to assess the deterioration of the spacer made by epoxy resin and to detect a loose connection in the central conductor. The principal results are summarized as follows:
(1) The quantity of decomposition gases depend on the moisture and magnitude of the partial discharge. However, decomposition gases were detected even if SF6 has low moisture content (less than 100ppm) similar to that used in actual equipment. This means that our method can be applied to actual equipment.
(2) It became clear that CF4 is a typical gas generated by partial discharge on the spacer surface. Therefore, it is possible to diagnose the deterioration of the spacer by monitoring the CF4.
(3) The decomposition gases (SF4, SO2, SO4, SO2F2) were generated by an impulse breakdown, which was assumed to be due to the repetition discharge caused by insulation failure and loose connection.
(4) SF6 gas which is assumed the loose connection and was heated up from room temperature to 800 degrees C, and the generated decomposition gases were analyzed by FTIR in real time. As a result, the decomposition gases were generated at temperatures above approximately 500 degrees C in the heating time of 1.5 minutes. Therefore, a loose connection can be detected by analyzing the decomposition gas.
