Development rule of temperature on oil-paper-insulated pin plate discharge under long-term operation Research

Zhao Zhong, Lu Xue

Heat aging, High and low temperature contrast, Heat aging, Needle plate discharge, Real and Simulation Oil paper insulation

In order to study the effect of temperature on the partial discharge of the oil-paper-insulated pin plate under long-term operation of the main transformer, we chose a vacuum heat aging 32-day simulation sample and a 28-year actual operation sample. And the step-up pressure method was used to test the local pressure of the needle plate of the two samples at ordinary temperature (30℃, 50℃) and high temperature (85℃ signal point, 105℃ trip point), and the relevant discharge characteristic quantity was analyzed by the partial discharge inspection instrument record.The results show:There is no significant difference between the heat-aged oil paper sample and the field sample in the early stage of discharge.However, there is a large difference in the development to the middle and late stages under the high temperature, especially the 105℃ trip point; The maximum discharge and total discharge at ordinary temperature near the breakdown time are both small, which is 2/3 of that at high temperature. The number of discharges gradually increased with the increase of compression time. The actual phase width and density of the actual samples at 105℃ during the middle and late periods of discharge were higher than those of the simulated aging samples. That is to say, the influence of high temperature on the oil-paper insulation of the main transformer during long-term operation is greater than that at low temperature. The oil-paper insulation level actually collected at the site increases with the extension of the operating time. It is easier to enter a dangerous period than a laboratory simulation sample at high temperatures, and the consequences of partial discharge are more serious.

https://dx.doi.org/10.31873/IJEAS.7.03.08