In order to meet the need of 500 kV GIS equipment to withstand the risk of overvoltage

a high potentialgradient GIS tank metal oxide arrester was developed. The structure and key technical parameters of the arresterwere introduced. The surface electric field strength of shield and resistor

internal potential distribution andmechani-cal properties of the shell were designed and calculated. High-gradient zinc oxide resistors were developed

and accel-erated aging test

internal insulation withstand voltage test

residual voltage test and power frequency voltage with-standtestwerecarriedout.The results show that the maximum electric field strength inside the tank is 18.97 kV/mm

the potential distribution unevenness coefficient is 1.059

and the safety factors of the tank shell under normal and faultconditions are 13.6 and 1.53

respectively. The aging coefficient of resistor is 0.8 at 95% charge rate

and passes thepower frequency voltage withstand test. The arrester passes the power frequency withstand test of 743 kV

lightningimpulse withstand test of 1 676 kV and switching impulse withstand test of 1 175 kV. The lightning impulse residualvoltage of arrester is 978 kV

the switching impulse residual voltage is 830 kV and the steep impulse residual voltageis 1 100 kV

which fully meet the technical requirements. The GIS metal oxide arrester has operating conditions.