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| Arc Flash Study Philosophy https://brainfiller.com/arcflashforum/viewtopic.php?f=4&t=6446 |
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| Author: | jimmy [ Thu Apr 30, 2026 3:36 am ] |
| Post subject: | Arc Flash Study Philosophy |
In Performing a study for example, with a secondary service at 480 volts and a 2500 KVA utility owned transformer, if you include the utility fuse on the primary of the transformer it could reduce the line side energy at the customer incoming PD. On the other hand, you have no control of the utility fuse which can change at any time without notice to the customer, so this would mean do not include the utility fuse. Thoughts, comments... thanks Jimmy |
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| Author: | stevenal [ Thu Apr 30, 2026 9:39 am ] |
| Post subject: | Re: Arc Flash Study Philosophy |
In my experience, utilities have consistent primary fusing based on transformer KVA. A simple fuse replacement will be of the same size. On the other hand, should a transformer require replacement, you might not get the same impedance or KVA. Best to check back periodically. |
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| Author: | bbaumer [ Sun May 03, 2026 1:28 am ] |
| Post subject: | Re: Arc Flash Study Philosophy |
I either don't model the fuse or I make it fail to operate as I have found it is difficult to get the primary side fuses to blow on a arcing fault "in real life" and it cannot be counted on to clear secondary faults quickly. |
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| Author: | mpparent [ Mon May 04, 2026 9:56 am ] |
| Post subject: | Re: Arc Flash Study Philosophy |
Like Brent mentioned, primary side fuses typically take too long to clear (or may not see the fault at all), so most software just defaults to the "2 second rule". Mike |
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