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| Software default inrush factor https://brainfiller.com/arcflashforum/viewtopic.php?f=23&t=2283 |
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| Author: | bruinfan [ Mon Jun 11, 2012 9:18 am ] |
| Post subject: | Software default inrush factor |
The software I use has a default inrush factor of 12. I have always used this default inrush factor for all my studies I have done. Recently I was told that the factor of 12 is not acceptable and that I should be using something more in the 6-8 range. Can anyone shine some light on this for me? |
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| Author: | Jim Phillips (brainfiller) [ Mon Jun 11, 2012 9:32 am ] |
| Post subject: | |
6-8 is certainly on the low end. I have always used the following (based on my Square D upbringing  )Liquid Filled or Unknown Transformer = 12X Dry Type = 10X Cast Coil = 8X However the actual inrush is also dependent on factors such as when in the voltage waveform the circuit is closed, past magnetizing history etc. so it is possible to have a lower inrush just based on these variables but the numbers above are what I use. |
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| Author: | bruinfan [ Mon Jun 11, 2012 9:42 am ] |
| Post subject: | |
Thanks for the reply. This helps! |
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| Author: | MattB [ Mon Jun 18, 2012 5:56 am ] |
| Post subject: | |
Be aware that it's not uncommon for new energy efficient dry type transformers (15-500 kVA) to have inrush factors in the 15-20 range. When purchasing a new transformer, ask the manufacturer for the specific information. When analyzing an existing facility, 12 is a good assumption. If there were actual inrush problems, it would be apparent and someone would be making some noise about it. I wouldn't recommend pointing out inrush problems according to the software in an existing facility where there are no real life inrush problems. |
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