Thermographic scan

[parlitu]

Is there any prescription that say from what voltage or current thermographic scan is relevant? If not, from yours experience can you give some values?
Thank you!

 

[magoo2]

A thermographic scan is probably more suitable for current carrying components and connections since the I-squared R effect will readily show up with infrared. Keep in mind that the current probably should be at least 50 % of rated current or greater to have maximum benefit of detecting potential problems. At a light load condition, the temperature rise won't be great enough to provide a reliable indicator.

While I lean more to using it for current carrying components, it will also provide effective results for early warnings with faulty arresters where moisture ingress leads to thermal runaway. We've also had good results in checking some of the newer solid dielectric potential transformers.

I don't think there is a limited voltage range for IR. We employ it with transmission voltages of 115, 230 and 500 kV and distribution voltages of 4, 12.5, 13.2 and 34.5 kV.

In a three-phase installation, I think using the maximum temperature is not as important as relying on the comparative temperature on like components on adjacent phases.

 

[eyec]

magoo2 has given a good response.
just remember than an IR scan is a snapshot of the conditions at the time and load conditions when the scan is performed.
if you are going to use it as a predictive tool you need baseline scans for low, normal, and high load conditions in order to detect possible deteriorations of components and connections.

again magoo2 hits a homerun with his last statement on comparative readings.

Steven C
Senior Member
ThirdPartyInspections.com