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

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?

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.