PURPOSE: To reduce a surge voltage applied to a protection resistance by forming a discharge gap between a tank and the shield ring closest to the side of a body to be tested among shield rings of a protection resistance device.
CONSTITUTION: The shield rings 16W23 for electric field relaxation are fitted to flanges 3, 6 and 9W12 and adapters 5 and 8. The rings 17 and 22 are larger than other rings 16, 18W21, and 23. A ring electrode 24 is fixed on the internal surface of the tank B so as to form the discharge gap with the ring 17 fitted to the flange 3. If a surge generated by the insulation breakdown of cables H and I is applied to the protection resistance, the discharge gap constituted between the ring 17 and electrode 24 is discharged and voltages applied to resistance bodies R1WR3 and coils L1WL3 are suppressed. Consequently, the surge voltage applied to the protection resistance is reduced.
AOYANAGI HIROKUNI
OKUBO HITOSHI
