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| Short Circuit Study - Motor Contribution https://brainfiller.com/arcflashforum/viewtopic.php?f=23&t=5573 |
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| Author: | makoester1 [ Tue May 10, 2022 3:05 am ] |
| Post subject: | Short Circuit Study - Motor Contribution |
Hello, When developing a model in order to run short circuit analyses, is it recommended to group LV motors <50HP? Upon looking at IEEE 399 and IEEE 551, this appears to be typical. Are individuals utilizing this technique or modeling all LV motors individually? Thanks for the input. |
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| Author: | mpparent [ Tue May 10, 2022 6:23 am ] |
| Post subject: | Re: Short Circuit Study - Motor Contribution |
I would use the red book as your go-to source, along w/ the purple/violet book. Per the red book, small motors are lumped into one "motor source" from a modelling perspective. Mike |
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| Author: | nickbramhall [ Tue Jul 12, 2022 1:03 pm ] |
| Post subject: | Re: Short Circuit Study - Motor Contribution |
Hello, I'm in the UK where we typically run short circuit studies in accordance with IEC 60909. That standard suggests that "for simplification of the calculation" groups of asynchronous low-voltage motors "may be combined to a single equivalent motor". We generally follow this advice with our modelling and combine LV motors at each switchboard or MCC. However, if there is a particularly large LV motor that may dominate a scenario (for example, an electric driven fire pump that is online when the system is in emergency mode) then we do model that as a standalone motor so we can switch it in/out as necessary. Combining LV motors also reduces the task of data collection! We typically only ask for detailed motor data for the largest LV motors - this is in case we need to add them for a particular scenario, or for use in other studies such as coordination. |
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