Superseded Standard

IEEE/AIEE 93-1962

AIEE Proposed Guide for Transformer Impulse Tests

Insulation is recognized as one of the most important constructional elements of a transformer. Its chief function is to confine the current to useful paths, preventing its flow into harmful channels. Any weakness of insulation may result in failure of the transformer. A measure of the effectiveness with which insulation performs is the dielectric strength. It was once accepted that low-frequency tests alone were adequate to demonstrate the dielectric strength of transformers. As more became known about lightning phenomena, and as impulse testing apparatus was developed, it became apparent that the distribution of impulse voltage stress through the transformer winding may be very different from the low-frequency voltage distribution. 2. Low-frequency voltage distributes itself throughout the winding on a uniform volts-per-turn basis. Impulse voltages are initially distributed on the basis of winding capacitances. If this initial distribution differs from the final low-frequency inductance distribution, the impulse energy will oscillate between these two distributions until the energy is dissipated and the inductance distribution is reached. In severe cases, these internal oscillations can produce voltages to ground that approach twice the applied voltage.

Superseded Standard

Working Group Details

Other Activities From This Working Group

Current projects that have been authorized by the IEEE SA Standards Board to develop a standard.

No Active Projects

Standards approved by the IEEE SA Standards Board that are within the 10-year lifecycle.

No Active Standards

These standards have been replaced with a revised version of the standard, or by a compilation of the original active standard and all its existing amendments, corrigenda, and errata.

No Superseded Standards

These standards have been removed from active status through a ballot where the standard is made inactive as a consensus decision of a balloting group.

No Inactive-Withdrawn Standards

These standards are removed from active status through an administrative process for standards that have not undergone a revision process within 10 years.

No Inactive-Reserved Standards

Sign up for our monthly newsletter to learn about new developments, including resources, insights and more.