This standard is applicable to string insulator units of the cap and pin type with insulating parts of ceramic material or glass, intended for a.c. overhead lines with a nominal voltage greater than 1000 V and a frequency not greater than 100 Hz.
It also applies to insulators of similar design used in sub-stations.
This standard applies to string insulator units of the cap and pin type either with ball and socket couplings or with clevis and tongue couplings.
This standard normally applies only to string insulator units for use on overhead lines in clean or moderately polluted areas. For use in heavily polluted areas and for insulators for use on direct current systems (see IE C Publication 438, Tests and Dimensions for High-voltage D.C. Insulators), it may be necessary for certain dimensions to be changed and insulator units having different creepage distances and spacing may be preferred.
In any case, it is recommended that the standardized mechanical characteristics of the present standard and coupling sizes are retained.
SIS SS IEC 305:1982 history
1982SIS SS IEC 305:1982 Insulators — String insulator units of the cap and pin type - Dimensions and characteristics