Gas-insulated metal-enclosed switches（GIS）have been widely used in power system due to their small floor area and high reliability.However

in the long-term operation of GIS

various internal insulation defects are inevitably generated and partial discharge phenomenon may occur concomitantly

which may even cause system failure.Therefore

in order to ensure the reliable operation of the system

it is of great significance to perform partial discharge on-line monitoring of GIS.Partial discharge detection has various detection methods such as electrical

acoustical

chemical and optical.Among them

electrical measurement methods mainly include pulse current method and ultra-high frequency（UHF）method.UHF method measures the electric field strength of electromagnetic waves emitted by partial discharge

while the pulse current method measures the apparent charge caused by partial discharge.The UHF method can extract the UHF components in the signal compared with the pulse current method

which has high sensitivity and can be monitored on-line.The intelligent GIS PD IED（intelligent electronic device）adopts the UHF+IED partial discharge monitoring method.In this paper

the feasilibility is studied that the sub-nanosecond pulse with a rising edge time of 253.75 ps

the FWHM is about 1.15 ns and a maximum peak voltage of 532 V（0 d B）is used to test the IED performance of the intelligent GIS.The results show that the output signal of UHF sensor is steady

IED displays positively correlation with the peak value of the sub-nanosecond pulse rather than a linear relationship

when the sub-nanosecond pulse is 30～50 dB

the results of IED are highly dispersed

so the sub-nanosecond pulse can be used to test the partial discharge IED performance test of intelligent GIS.