老化对牵引变压器油纸绝缘局部放电特性的影响

随着牵引变压器运行年限的增加,高温部位采用的芳纶绝缘纸逐渐老化,容易发生局部放电,严重影响牵引变压器的安全运行。本文搭建了油纸绝缘老化和局部放电试验平台,分析老化对油纸绝缘局部放电特性的影响机制。结果表明:老化使局部放电平均放电量、最大放电量、放电重复率增大。放电重复率的变化可以在较低的外施电压下反映出老化对油纸绝缘局部放电特性的影响。老化后的试样表面在局部放电作用下更容易形成黑斑,且分支数目更多,这是由于浆粕老化以及老化导致短切纤维和浆粕界面粘合度降低造成的。

Effect of Ageing on Partial Discharge Characteristics of Oil-paper Insulation for Traction Transformer

With the increase of the operating period of traction transformer, the aramid insulation paper used in the high temperature part ages gradually and is easy to produce partial discharge, which seriously affects the operation safety of traction transformer. In this paper, an oil-paper insulation ageing and partial discharge experimental platform was built, and the influence mechanism of ageing on the partial discharge characteristics of oil-paper insulation was studied. The results show that the average and maximum discharge amount and the partial discharge repetition rate increase with ageing. The influence of ageing on the partial discharge characteristics of oil-paper insulation can be reflected by the change of discharge repetition rate at lower applied voltage. Black spots are easier to form and divide into more branches on the surface of aged samples under partial discharge, this is because the ageing of pulp and the decrease of interfacial adhesion between chopped fiber and pulp.