Judging Discharge Type in Git by Gas Component Analysis

Distribution transformers are an important part of distribution networks. The gas-insulated transformer internally replaces the transformer oil with SF6. Due to this limitation, low-voltage, low-capacity gas-insulated transformers have more mature technology level and wider application field because of their low cost and difficulty in production. Due to its good safety, flexible installation methods, and no need for oil pits and clean oil equipment, it has broad application prospects in the field of distribution transformers. Different types of discharge occur in the solid insulation of gas-insulated transformers. In order to judge the type of discharge in the internal insulation of the gas-insulated transformer and the severity of the fault, three kinds of electrode models were used to simulate the corona discharge, internal discharge and external discharge of the insulation in the gas-insulated transformer. The corona discharge model is a needle plate electrode with 20mm distance, the needle-plate electrode against the surface of the intact insulation as the external surface discharge model. Artificially add a crack to the insulator and let the needle-plate electrode discharge along the crack. Use this method to simulate the internal surface discharge. The characteristic decomposition products of the specific discharge form were determined by comparing the different kinds of decomposition products and the content of the decomposition products in the SF6 environment. The discharge form of the gas-insulated transformer were determined for the on-line monitoring. At the same time, we can make sure whether a fault occurs or a crack is appeared on the insulation.