This standard is applicable to ceramic and resin insulated bushings for rated voltages above 1 kV up to 36 kV rated currents from 250A up to 3150 A and frequencies from 15 Hz up to 60 Hz for insulating liquid filled transformers. This standard establishes essential dimensions, to ensure interchangeability of bushings and to ensure adequate mounting and interchangeability of mating plug-in separable connectors of equivalent ratings