大电机主绝缘多因子老化试验中试样线棒端部防晕技术的研究

Study on Anti－Corona Technique at the Ends of Stator Bar Specimen in the Multi－Stress Aging Test for Lrge Generator Stator Winding Insulation

大电机在长期的运行过程中要遭受电、热、机械等多因子的联合作用，使其绝缘逐渐老化。为了研究其老化机理，评估其剩余寿命，需要对试样线棒进行多因子应力老化试验，并测试能反映其老化程度的特征参数。本文对电老化试验和局部放电检测过程中当电压升高时试样线棒端部出现电晕、闪络现象进行了理论分析，提出了试样线棒端部防电晕的技术方案。试验结果表明，利用碳化硅合成半导电漆作为防晕层可有效地防止试样线棒的端部电晕。

In the course of actual operation, the large generator stator winding insulation experiencevarious stresses, such as electrical, thermal and mechanical stress and deteriorate in dielectric strength. It isnecessary to conduet the accelerated multi-stress aging test on generator stator bar specimen in order to exploreit's aging law, prediet it 's remaining life and find a set of characteristic parameters which can indicate thecondition of the insulation. The theoletical arlalysis is carried out in this paper on corona and flash overphenomena presented at the ends of stator bar specimen in the course of electrical aging and partial dischargedetection when the electrical strength applied becomes high. The technical schemes for anti-corona and antiflashover have been presented in this paper. The experiments have been conducted on actual rotating machinebar specimen coated with SiC anti-corona synthetic product and it is verified that the technique is effective toprotect the ends of stator bar specimen apainst corona and flashover.