In order to further study the effect of active trigger circuit on the protection characteristics of surge protection gap（SPG）

we experimentally studied the effect of each component in the active trigger circuit. The experimental results show that the voltage of piezoresistor in the trigger circuit is dividually loaded by the static capacitance and the series capacitor before the action. When the piezoresistor in the trigger circuit is added

the increment in the SPG breakdown voltage is the action voltage of the piezoresistor. The smaller the U

1mA

voltage of piezoresistor is

the wider the SPG protection range will be

however the smaller the ratio-voltage K is. With the increase of the breakdown voltage of gas discharge tube（GDT）

the breakdown voltage of SPG increases

but the smaller the GDT breakdown vol

tage is

the wider the SPG protection range will be

and the response time of SPG is greatly influenced by GDT. The breakdown voltage of SPG increases with the increase of capacitance

but the scope of the protection is not changed basically. The research results can provide an experimental basis for optimizing the performance of the active overvoltage protection gap trigger circuit.