scope:

This test procedure for the thermal evaluation of insulation systems of dry-type power and distribution transformers is to be used for determining the temperature classification and modification of the insulation systems. This standard shall apply to all dry-type transformers with a voltage of 601 V or higher in the highest voltage winding except as follows:

a) Instrument transformers

b) Step- and induction-voltage regulators

c) Arc-furnace transformers

d) Rectifier transformers

e) Specialty and general-purpose transformers

f) Mine transformers

g) Testing transformers

h) Welding transformers

NOTE-Where IEEE standards do not exist for the transformers mentioned above or for other special transformers, this standard may be applicable as a whole or in parts subject to agreement between the parties responsible for the application and for the design of the transformer.

Purpose

The purpose of this test procedure is to establish a uniform method for the following:

a) Acquiring data used to determine the temperature classification of an insulation system

b) Acquiring data that may be used as a basis for a loading guide, such as IEEE Std C57.96™³

c) Modifying an established electrical insulation system

³Information on references can be found in Clause 2.