Writeup Wednesday: Arc Flash Protection
Updated: Sep 17, 2020
Someone on our LinkedIn asked recently:
"What recommendations does OneStep Power Solutions have regarding “Arc Flash” protection?"
We thought we'd publish the answer here so we can help others with questions about this as well.
Sorry for the belated reply on this! Here’s a quick answer, we look forward to providing a more detailed post on this subject in the future.
Arc flash is an interesting topic indeed, and just like many other things in life prevention is better than detection and cure. We at OneStep are very much of the opinion that it is important to consider arc flash prevention from the initial concept right through the service life of the generation and distribution system.
In the design and construction of a switchboard it is important that not only the big things like insulated bus bars, arc flash ratings, arc flash detection and arc flash suppression are considered but just importantly, the small things like circuit breaker phase barriers and correct sealing with withdrawable style circuit breakers on the doors where the phase poles connect. Inspection windows for both visual and IR are nice to ensure easy and correct maintenance can be conducted. Switchboards should be sealed to prevent rodents and contaminants entering as much as possible.
In service it is very important to carry out inspection and maintenance on switchboards and switchboard room services. Things like visual inspections to ensure there is no contaminant build-up and IR to ensure no hot spots are developing that can lead to arc flash faults. Just as important is the maintenance of switchboard area services such as regular filter changes on-air systems and rodent traps/baits to prevent things like mice and rats causing an arc flash event.
While good design and maintenance plans can significantly reduce the possibility of an arc flash event there always remains the chance that something unexpected happens. In this unlikely and undesirable case, it is always good to have an effective detection and response system in place. There are a lot of good systems out there to detect an arc flash. These systems generally use one or a combination of optical, pressure and current. They will normally open breakers that are supplying energy to the switchboard that has been identified as having the fault.
In addition to simply opening the breakers, a number of manufactures also offer arc flash reduction devices that will close all three phases to ground on detection of an arc flash. These devices give the energy being released in the fault an easier path to follow which results in a reduction of damage to the system.
We hope this helps!
We also found a couple of great references on this topic:
Good news doesn’t usually make the news: stay safe with passive arc protection in medium-voltage switchgear
IEC 61850 based GOOSE messaging in arc protection of LV/MV switchgear