IEEE 638:2013

Revision Standard - Active.
Procedures for demonstrating the adequacy of new Class 1E transformers, located in a
mild environment of a nuclear power generating station, to perform their required safety functions
under postulated service conditions are presented. Single- and three-phase transformers rated
601 V to 15 000 V for the highest voltage winding and up to 2500 kVA (self-cooled rating) are
covered. Because of the conservative approach used in the development of this new standard for
new transformers, the end-point criteria cannot be used for in-service transformers.

This standard provides requirements to demonstrate the adequacy of new Class IE transformers, located in a mild environment of a nuclear power generating station as defined in IEEE Std 323™1, to perform their required safety functions under postulated service conditions. This standard applies to single- and threephase transformers rated 601 V to 15 000 V for the highest voltage winding and up to 2500 kVA (base rating).
The purpose of this standard is to provide specific qualification procedures for Class lE transformers to demonstrate their capability to meet the requirements of IEEE Std 323. The transformer shall perform its intended function under all specified service conditions