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Three winding Transformer and Incident energy
https://brainfiller.com/arcflashforum/viewtopic.php?f=15&t=5776		 Page 1 of 1
Author:  Beca_Zion [ Tue Feb 20, 2024 5:30 pm ]
Post subject:  Three winding Transformer and Incident energy
This is the first time to deal with three winding Transformer in SKM.
I have a three Winding transformer with 1.5MW Secondary and 0.5 MW Tertiary. I had to modify the Tertiary side of the transformer by adding more load and CBs into it. Now the Tertiary side has less incident energy. which is good.
However, the secondary side, even though I haven't change anything, has be affected. The arc Flash incident energy has jumped from 6.0 Cal/cm^2 to almost 80Cal/cm^2. Could that be possible?

Noting it's a huge transformer so for the incident energy to reach 80 cal/cm @ 2Sec is possible.


Thanks
Author:  bbaumer [ Wed Feb 21, 2024 6:51 am ]
Post subject:  Re: Three winding Transformer and Incident energy
Not enough information to answer as I'd have to see the protection scheme but my question is, what type of transformer is this and what are the voltages? Are you actually labeling it? What are you using for box size or is this a substation transformer with terminations in open air? What are you using for bus gaps?

I seen others blindly model transformers with the default "PNL" or "SWG" VCB without accounting for the actual enclosure size or bus gaps or if it is in the air and not a box etc. and the results are not reality.

Voltage may also be an issue and SKM might not be the right tool, or it may be.

Again, not enough information.

Also, need to make sure you have the transformer data completely input accurately.

https://www.skm.com/applicationguides5.html

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