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Dry-type power transformers are air cooled, having no liquid insulation. Typical
applications include station service and excitation system transformers.
applications include station service and excitation system transformers.
Maintenance or Test
Recommended Interval
Reference
Review equipment ratings
5 years
NERC Planning Standard
Infrared scan
Annually
NFPA 70B, 18-17
Transformer FIST Volume 3-30
Transformer FIST Volume 3-30
Temperature alarm check
Annually
NFPA 70B, 7-3 and
Appendix H
Transformer FIST Volume 3-30
Appendix H
Transformer FIST Volume 3-30
Visual inspection/cleaning
Annually
NFPA 70B, 7-3 and Appendix H
Transformer FIST Volume 3-30
Transformer FIST Volume 3-30
Check fan operation
Annually
NFPA 70B, 7-3 and Appendix H
Transformer FIST Volume 3-30
Transformer FIST Volume 3-30
Clean fans and filters
Annually
NFPA 70B, 7-3 and
Appendix H
Transformer FIST Volume 3-30
Appendix H
Transformer FIST Volume 3-30
Turns ration test
3-6 years or if problems are
suspected
suspected
NFPA 70B, Appendix H
Insulation resistance test 3-6 years or when problem
of windings is suspected
NFPA 70B, Appendix H
Oil filled transformers generally deliver power to and from the main units of the
facility--for example, generator step-up transformers. These transformers are
generally located outside the building in a transformer bay or in a switchyard.
These transformers may be two-winding or more and include autotransformers.
facility--for example, generator step-up transformers. These transformers are
generally located outside the building in a transformer bay or in a switchyard.
These transformers may be two-winding or more and include autotransformers.