scope:

This standard applies to the insulation systems used in all liquid-immersed distribution and power transformers. This standard provides test procedures to evaluate the thermal aging characteristics of insulation systems used in liquid-immersed distribution or power transformers. The dielectric liquid is part of the insulation system.

Purpose

The objective of this test procedure is to establish uniform methods for investigating the effects of operating temperature on the life expectancy of liquid-immersed transformer insulation systems. The results of these test procedures are expected to

a) Provide the basis for the selection of a limiting hottest-spot temperature for rating purposes

b) Provide life curves that may serve as the basis for a guide for loading

c) Permit the comparative evaluation of a proposed insulation system with reference to an industryproven system that has been shown to be acceptable in service