Brett, I work for a data center company. We have over 500 MV transformers - most 34.5 KV. We have conducted annual DGA sampling which has revealed some problems and abnormal results. About 3 years ago I started including annual IR, ultrasonic and partial discharge testing when obtaining the sample. We had to add IR windows to most of them. Annually has worked. They aren't critical enough to justify continuous monitoring. I have continuous monitoring on 3 HV transformers 69 KV for vibration. Looking to extend to all of our HV transformers. There are provisions in NFPA 70B for predictive monitoring.
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Lee McClish
Director, Maintenance and Reliability
NTT Global Data Centers Americas
Ashburn VA
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