Hi All,

I have been doing thermography for a while now and on substations to be particular, last year, I carried out one, and on looking at the final verdicts I gave on some of the switchgears, I believe I may have gone for higher severity levels during analysis than is necessary but this was based on the following standards/ guidance I could get at the time:

1. Thermographic analysis is in accordance with IEEE Std 242-2001 - IEEE Recommended Practice
for Protection and Coordination of Industrial and Commercial Power Systems (Buff Book)
regulation 16.11.3.2, NFPA 70B regulation 11.17.5.6 & ATS table 100.18.
2. Even though BS 7671 does not recognize thermographic surveying equipment as a test instrument,
it’s importance is elaborated in IET Guidance Note 3 – Inspection & Testing updated to BS
7671:2018+A2:2022 Page 144.
3. It was observed that the Transformers within the compact stations were operating at high
temperatures between 63 - 70°C while they were rated for optimum operation at 40°C at a system
loading of over 60%, at the same system loading, the power transformers were operating at
temperatures of 44-45°C.

could someone point me to some guidance codes or standards on how to go about doing analysis on HV, it's a little easy and straight forward on LV systems but not so where transformers are involved, thanks in advance.