the secondary circuit plays an important role in guaranteeing the security of power product and supplying high-quality electrical energy for customers . however, there has not been an on-line monitoring device that can monitor the multipoint earth of the secondary ac circuit 二次系統(tǒng)對保證電力生產(chǎn)安全及向用戶提供高質(zhì)量的電能起著極為重要的作用,但目前尚沒有一種能在線監(jiān)測二次交流回路是否存在多點接地的在線監(jiān)測裝置。