高电压多脉冲冲击下单片与双片并联的MOV性能

Performance Analysis of Single and Parallel ZnO Varistor Under Multiply Strokes

采用幅值为20 k A、时间间隔为50 ms的同时序冲击高压5脉冲分别对单片氧化锌压敏电阻元件、2片压敏电压相差10 V、2片压敏电压相同的并联压敏电阻进行冲击试验。试验表明单片压敏电阻难以承受多脉冲的大能量,将幅值为40 k A同样的波形施加在2片压敏电阻并联上时,2片压敏电压相同的压敏电阻并联耐受冲击次数是单片情况下的2倍,而压敏电压相差10 V的2片压敏电阻并联的耐受冲击次数甚至比单片少。通过对多脉冲冲击下的压敏电阻片电气参数、温度测试分析以及外观损坏形式分析,认为多脉冲情况下的损坏机理主要以热击穿为主。

8/20 μs multiply strokes are applied to ZnO varistors with 20 kA amplitude and 50 ms time interval. The experiments are performed on single ZnO varistor, parallel ZnO varistors with 10 V potential difference and parallel ZnO varistors with zero potential difference. The experimental results show that single ZnO varistor cannot bear huge energy of strokes. The bearing capacity of parallel varistors are doubled compare with single ones with same 40 kA waveform. However, with 10 V potential difference, the bearing capacity of parallel ones is even less than single configuration. By investigating electrical characteristic, temperature and feature variation of ZnO varistor under the multiply strokes, it is found that major damage mechanism of ZnO varistor is thermal breakdown.