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| "Crowbar" Arc energy-reducing active arc flash mitigation https://brainfiller.com/arcflashforum/viewtopic.php?f=33&t=4784 |
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| Author: | Jim Phillips (brainfiller) [ Sun Oct 21, 2018 1:12 pm ] |
| Post subject: | "Crowbar" Arc energy-reducing active arc flash mitigation |
An arc energy-reducing active arc flash mitigation system sometimes known as a "Crowbar" is one method to reduce the incident energy from an an arc flash. This week's question: Have you/company/clients ever used the "Crowbar" method for arc energy reduction? Yes No Doesn't apply Stories, comments and discussion are quite welcome! |
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| Author: | Gary B [ Mon Oct 22, 2018 9:05 am ] |
| Post subject: | Re: "Crowbar" Arc energy-reducing active arc flash mitigatio |
This was being implemented at a mill I was also about to begin analysis at, but the mill was shut down before the purchased equipment was installed. It was a bit unnerving to consider the stress such system would impose on line side distribution, my concern was that shorting out the arc energy might cause a greater failure of aged transformers or insulated cables upstream, however; those were only casual thoughts and reality is that a blown up power system is a lot more acceptable than an injured worker. Never saw it come to be installed much less operated. |
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| Author: | ScottPET [ Mon Oct 22, 2018 2:04 pm ] |
| Post subject: | Re: "Crowbar" Arc energy-reducing active arc flash mitigatio |
In a previous life in Sales, remote Aust energy utilities used what they called a fault-thrower. It wasn't specifically for reducing arc flash per se, but it was a stand alone unit designed to close phase to earth when a high impedance fault was detected at the end of long OH lines (i.e. with low prospective fault levels), turning it into a bolted fault that the CB would then operate on quickly. That was over 20yrs ago, when induction disc protection relays were still the norm in these utilities, before numerical relays. |
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| Author: | GBISON [ Mon Oct 29, 2018 2:49 pm ] |
| Post subject: | Re: "Crowbar" Arc energy-reducing active arc flash mitigatio |
Had an activation of an Arcon unit on LV incomer in anger. It did the job. Have not tried UFES to my knowledge. As for concerns about bolted faults, have had a few switching incidents where portable earths and earth switches have been left on. Disruption, but no real damage of concern. Tend to refer to them as arc quenching devices. |
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| Author: | SteveA [ Mon Nov 05, 2018 10:12 am ] |
| Post subject: | Re: "Crowbar" Arc energy-reducing active arc flash mitigatio |
My company has installed several UFES systems. I think we may have been the first company to install one at a customer site in the U.S. They were used to initiate a transformer primary fuse to blow for an arc detected on the switchboard on the secondary side of the transformer. So far it has not needed to fire, and we are not in the process of replacing those substations with brand new substations; though it will be a 5-10yr project overall due to the number of, and complexity of. |
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