1.1 Subject contents
This Standard specifies the procedure for the selection of the standard withstand voltages for the phase-to-earth, phase-to-phase and longitudinal insulation of the equipment. It also gives the lists of the standardized values from which the standard withstand voltages shall be selected.
During the preparation of equipment standards, the withstand voltages and the test procedures suitable for the relevant equipment shall be specified according to the requirements of this Standard.
1.2 Application scope
1.2.1 This Standard is applicable to three-phase a.c. systems having a highest voltage for the following indoor and outdoor power transmission and transformation equipment above 1 kV.
a) Transformers: power transformer, parallel reactor, arc suppression coil and inductive voltage transformer;
b) High voltage electrical apparatus: breaker, isolating switch, load switch, earthing short circuiter, fuse cutout, limiting reactor, current transformer, enclosed switch equipment, enclosed combined electrical equipment, combined electrical device, etc.;
c) Combined type (cabinet type) transformer station;
d) Power capacitor: coupling capacitor (including capacitor voltage transformer), parallel capacitor and AC filter capacitor;
e) High voltage power cable;
f) Insulator and wall bushing of transformer station;
g) Insulating coating of valve type arrester.
1.2.2 The Standard is not applicable to:
a) Equipment installed at the place with serious pollution or with harmful gas, steam or chemical sediment to the insulation;
b) Indoor equipment installed at the place with higher relative humidity and subject to condensation.
