Gas discharge includes many pre-discharge current pulses with nanosecond-level rise-time and milliampere-level amplitude

and the breakdown current after pre-discharge process can reach up to kiloampere level.To measure pre-discharge current safely and accurately

a novel Rogowski coil with the function of overcurrent protection was designed.In the design scheme

a transient voltage suppressor（TVS）was connected in parallel with the self-integral resistor of Rogowski coil.The parameters of the self-integral resistor and overvoltage protection device were optimized on the basis of many experiments

and the res

ults show that the integral resistor must be decreased for broadening frequency band of Rogowski coil when the measuring sensitivity is satisfied

the optimal value of resistance is in the range of 10

5

0 Ω

the response time of the overvoltage protection device must be shorter than the rise time of the measured current

and the distributed capacitance of TVS must be reduced to 0.5

1

nF when the peak current of the Rogowski coil is larger than the circuit breakdown current.Test results show that the new Rogowski coil can accurately measure milliampere-level current with rise-time shorter than 5 ns

and can protect measuring device in the presence of kiloampere-level current.