The thyristor in the improved capacitor var compensation device of thyristor series voltage regulation endures unsafe off-state over-voltage when it switches off on line.

• 改进式晶闸管串联调压电容无功补偿装置的晶闸管开关带电断开时,要承受危险的断态过电压,为保证装置的安全运行,阐述了晶闸管断开时过电压产生的原理及状态。