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| does regular motor or VFD motor affect Arc flash results? https://brainfiller.com/arcflashforum/viewtopic.php?f=15&t=5511 |
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| Author: | luckywen [ Thu Sep 23, 2021 12:59 pm ] |
| Post subject: | does regular motor or VFD motor affect Arc flash results? |
Hello everyone, I am new to SKM modeling and arc-flashing study. Now I am having a one line with a transformer lowside feeds to a 4.16kv switchgear without a CB, but a MOD switch, and in this switchgear, there are 5 feeders, each one has a feeder breaker, and one feeder is to a VFD controlled motor. my question is in SKM modeling, is there any arc-flashing study result difference in SWGR to model the load as a regular motor or a VFD controlled motor? Thank you |
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| Author: | wbd [ Fri Sep 24, 2021 5:14 am ] |
| Post subject: | Re: does regular motor or VFD motor affect Arc flash results |
If the VFD's are non-reg type then there will be no backfeed of motor current to the switchgear. Since it is 4.16kV motors I suspect them to be healthy horsepower and may have a significant contribution if there is backfeed. Since you are working in software, why not create a model with non-regen VFD's and one with straight motor connection the bus, fault the bus and compare which is the worst case and by how much? |
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| Author: | luckywen [ Fri Sep 24, 2021 7:13 am ] |
| Post subject: | Re: does regular motor or VFD motor affect Arc flash results |
Thank you for the reply. You are correct, I did the modeling comparation, and the result shows the one with VFD has a little bit lower incident energy level back in SWGR. it seems that a directly connected motor will contribute some energy back to SWGR. Really appreciate the help. |
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