Dielectric Tests for EHV Transformers

Specific proposals for revision of dielectric tests for EHV power transformers are made. An objective is improved operating reliability by specifying tests which are more compatible with service requirements. Impulse and switching surge tests are coordinated independently with lightning arrester characteristics. Low-frequency tests are disassociated from transient voltage requirements and are related to operating voltage only. Low-frequency test voltages are reduced and their duration is increased; absence of corona during the test is required. Suggestions for further development work are made.