In this paper

the loss and overvoltage of capacitor unit for differential protection wiring

which is launched recently for 10 kV frame type shunt capacitor devices

is simply calculated and analyzed

and it is concluded that inside the capacitor unit

used in this device

only two serial section

high current of capacitor in normal operation

additional loss increase

heating problems easy to appear. In case of capacitor failure

overvoltage transmission is easily happened. The capacitor and the intact series section are damaged by heating of capacitor and its connectors as well as overvoltage transmission

which will bring hidden danger for operation. Therefore

such wiring at 10 kV frame type capacitor type shall be used as less as possible so to avoid fault development of capacitor device endanger safety of power system.