Loss measurement for transformer in operation
Loss measurement for transformer in operation
(OP)
Hi!
Are there any methods to measure losses of transformer in operation or to calculate transformer losses by use of rating, measured voltage & amperes and nameplate data?
Please let me konw the method or any reference books.
Thanks in advance for your advice.
Are there any methods to measure losses of transformer in operation or to calculate transformer losses by use of rating, measured voltage & amperes and nameplate data?
Please let me konw the method or any reference books.
Thanks in advance for your advice.






RE: Loss measurement for transformer in operation
RE: Loss measurement for transformer in operation
Possibly IEEE Std C57.12.90-1999 …Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers, and IEEE Std C57.123-2002 Guide for Transformer Loss Measurement
RE: Loss measurement for transformer in operation
RE: Loss measurement for transformer in operation
I agree with jghrist - power transformers are incredibly efficient and any attempt at loss measurement will be seriously compromised by instrument transformer error and metering error.
RE: Loss measurement for transformer in operation
RE: Loss measurement for transformer in operation
RE: Loss measurement for transformer in operation
Any particluar reason, you want to measure the losses now ?
RE: Loss measurement for transformer in operation
but it looks like expensive solution comparing to Voltage and Current difference losses neasurement method.
RE: Loss measurement for transformer in operation
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If we learn from our mistakes,
I'm getting a great education!
RE: Loss measurement for transformer in operation
RE: Loss measurement for transformer in operation
If for metering or cost, the morale of story is that the losses are so small that its within meter's error margin and it will not be worth measuring, as you could pay 1-2% more or less even if you have a 100% efficient xfmr and a less accurate meter.
If you need to know heat gain for sizing cooling or ventilation, the rules of thumb, 1.5 to 2% of the rating, is more than sufficient.
However in theory wattmeter measurement is only viable method, all you have to get is accurate meter/sensors.
The tranformer manufacrture can always provide with the no load losses and full load I2R losses, just ask them. (It is another matter they may also come with those data by typcial Watt measurement)
No load losses are constant and you can always intrapolate I2R losses at any load from 0 to full load as R remains relatively constant. (Purists: do not throw in change in R due to temp....not worth it).
In absence of data you go with rules of thumb, say for sizing cooling or ventilation...
RE: Loss measurement for transformer in operation
As I understand it, Rogowski-based sensors can be built with errors in the ppm level, far better than any conventional CT I have seen. I think the limiting factor in this case may be voltage measurement - I'm not aware of VT's in a comparable accuracy class and I do not think anyone would dare use a resistive divider for this application.
This is an interesting exercise.
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If we learn from our mistakes,
I'm getting a great education!
RE: Loss measurement for transformer in operation
It is possible to make a CT just as accurate as a Rogoski coil. The trick is to tune the CT to the exact burden being placed on it. If one knows the burden ahead of time, a CT can be designed to be almost perfectly accurate. The limit on the accuracy rating is only limited by the level of accuracy of the calibration equipment.
Same goes for VTs.
The reasons CTs and VTs are generally rated by normal standard classes is because the devices must maintain an accuracy class over a range of burdens and therefore must be designed such that the low and high burden rating are within class.
RE: Loss measurement for transformer in operation
Thanks for the info - I figured it was theoretically possible, but I've never seen a CT better than Class 0.1. Now I know better!
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If we learn from our mistakes,
I'm getting a great education!
RE: Loss measurement for transformer in operation
Generally, 0.05% is about the best that can offered, which is about the best you can calibrate to, since I believe you try to keep 10 times better accuracy with the calibration equipment compared to the test sample.