The Method and Theoretical Analysis of Parallel Connection of Varistors in Surge Protective Devices
Maohua Wang · Insulators and Surge Arresters · 2004
The lightning discharge current withstand capability of varistors in surge protective devices is improved by parallel connection.The current deviation is due to the difference in clamping voltage(U_(a1)≠U_(a2)) and dynamic resistance(R_(z1)≠R_(z2))according to the theoretical analysis of electrical characteristics of parallel varistors,the higher the dynamic resistance,the lower the current deviation.When the parallel connection of varistors is carried out,the clamping voltage(U_a)shall be set equal,and the difference of dynamic resistance(R_z)being within the specified tolerance,or the dynamic resistance set equal,and the difference of clamping voltage being within the specified tolerance,which makes the current deviation in the range of 10%.