Transformer-Infrared shows much higher temperature than oil & winding
Transformer-Infrared shows much higher temperature than oil & winding
(OP)
We loaded the 75MVA transformer up to .92PU and performed infrared scanning and meantime observed changes of top oil and winding hottest spot temperature gauge.
4 hours after the uploading, the top oil and winding hottest spot readings are 51C and 71C respectively. It's consistent with the heat run calculation based on IEEE 57.91. But the the infrared showed that the hottest spot was at the lower part of the tank (at the side), it's 84C, while infrared readings of other parts were less than 45C.
The ambient temperature at the time of testing was about 60F, and it's overcast.
I thnik in the normal situation, the the infrared scanning temperature reading should be less than the winding hottest spot temperature reading.
I would like to hear your opinion.
THanks
4 hours after the uploading, the top oil and winding hottest spot readings are 51C and 71C respectively. It's consistent with the heat run calculation based on IEEE 57.91. But the the infrared showed that the hottest spot was at the lower part of the tank (at the side), it's 84C, while infrared readings of other parts were less than 45C.
The ambient temperature at the time of testing was about 60F, and it's overcast.
I thnik in the normal situation, the the infrared scanning temperature reading should be less than the winding hottest spot temperature reading.
I would like to hear your opinion.
THanks






RE: Transformer-Infrared shows much higher temperature than oil & winding
RE: Transformer-Infrared shows much higher temperature than oil & winding
Pull the oil sample (dga) monitor combustible gases...
RE: Transformer-Infrared shows much higher temperature than oil & winding
RE: Transformer-Infrared shows much higher temperature than oil & winding
If you have adequate access, you might want to corroborate your IR temperature with a contact temperature reading at the site of the hot spot.
A hot spot on the case can indicate factors as Dandorian indicated, as well as something causing stray flux to interact with the case resulting in heating due to currents induced in the case wall.
old field guy
RE: Transformer-Infrared shows much higher temperature than oil & winding
Can you actually post the thermal image - there may be some clues.
=====================================
(2B)+(2B)' ?
RE: Transformer-Infrared shows much higher temperature than oil & winding
Electripete - Sure, I will send the image a little later.
THanks
RE: Transformer-Infrared shows much higher temperature than oil & winding
RE: Transformer-Infrared shows much higher temperature than oil & winding
You can differentiate this by following the below procedure.When putting on full load from cold condition, watch the temperature in the observed area-it will rise with in 10-15 minutes to 70-80 C while the oil temperature is still in cold condition.
Anyway 84 C is not a cause for concern,provided it is not going above 110 C in peak summer under full load.
RE: Transformer-Infrared shows much higher temperature than oil & winding
RE: Transformer-Infrared shows much higher temperature than oil & winding
One more thought: is this an LTC? If so, what tap position was it in? It could have been the preventative auto heating up.
------------------------------------------------------------------------
If it is broken, fix it. If it isn't broken, I'll soon fix that.
RE: Transformer-Infrared shows much higher temperature than oil & winding
http
RE: Transformer-Infrared shows much higher temperature than oil & winding
No SFRA done. Not likely it has the loose winding issue.
The load is fairly balanced, and it's not with LTC.
RE: Transformer-Infrared shows much higher temperature than oil & winding
On the picture looks like only one pump is running.
RE: Transformer-Infrared shows much higher temperature than oil & winding
I will go to check the pump tomorrow.
How did you identify that one pump was not working?
RE: Transformer-Infrared shows much higher temperature than oil & winding
RE: Transformer-Infrared shows much higher temperature than oil & winding