New concept for arc flash reduction

A containment dome? Nice concept but sounds expensive. Any thoughts?

http://www.youtube.com/gearcflashinnovation#p/u

Interesting approach! Guess it is better than replacing the gear, but probably not cheap.

I can't get to the link from here, but if this is the new GE arc flash addition, it is an interesting approach. They presented this at the PCIC in September in Anaheim, and had a demo unit on display.

The unit, as I understand it, uses a light detection system with an overcurrent relay to initiate the operation of their device. Instead of a crowbar switch type device, they instigate another arcing fault within the containment. This, coupled with tripping the upstream device through auxillary relays can dramatically reduce the energy seen in the first arc flash event. The unit can be added onto existing gear because it's about the size of a standard MCC segment.

It is a nice concept, that takes a lot of the "heebies" out of a crowbar switch.

i'm having a hard time figuring how starting another arc will reduce the primary arc

the optical detection will shorten time ok for that part
but the second arc ??

The optical detection can be tied to the trip mechanism on an upstream breaker, but this is not necessary for this concept.
If it is tied to an upstream breaker, you must still wait for the breaker to operate. This could be several cycles.

By creating a second arc, they are reducing the system voltage available to drive the primary arc. The current demanded by the second arc, because (they say) it is lower impedence than the first arc, will draw current and energy from the first.

To see the arc vault sales video visit this site:http://www.geindustrial.com/products/static/switchgear/arc_vault.htm
Interesting, how the plasma gun redirects the flash to the containment dome. Thats like watching Scotty put up the shields on the Enterprise to protect the ship, just to cool.

Equipment to Reduce Arc Flash Dangers

Sq D has also the ARC FLASH Terminator
http://ecatalog.squared.com/pubs/Electrical Distribution/0613BR0302.pdf

More info on SQ D ARC FLASH Terminator

See attached PDF file

WDeanN is correct

Hello, in the interest of disclosure, I work for GE ! Below is a very simplified explanation of how the arc vault works.

The system is comprised of three major subsystems:
1 Arc flash detector such as an arc flash relay
2 Arc Vault device to absorb system energy, similar in purpose to a crowbar
3 Low or medium voltage circuit breaker to stop current flow

The arc flash detection system which could be an arc flash relay, or could be a simple current detection system that compares current measured to a threshold, is used to sense for an arc flash event. It controls the Arc Vault triggering mechanism and a line side circuit breaker.

The Arc Vault simply provides an alternate current path for current via an arc it creates inside of itself. That arc has lower impedance and is more stable than an arc on an equipment bus system or other conductors inside an enclosure. The arc in the Arc Vault will become the only arc that conducts current as the system voltage will drop enough that the other arc will extinguish. Inside the enclosure the arc is kept controlled and separated from the immediate environment.

The circuit breaker will start operating at the same time as the Arc Vault, however it is much slower. The Arc Vault once commanded should extinguish the fault arc within a millisecond or so. The circuit breaker may take 3-5 cycles. However, in the interim the arc is in the Arc Vault not where the fault arc originally started or in the open environment.

The intent of the device is to provide an alternative to a crowbar with the benefits of a crowbar and arc resistant equipment with regard to hazard reduction, but without the concerns created by having maximum bolted fault current flowing through the system. In addition allowing testing of the system in the field. All testing up to now indicates this is, indeed, the case. A system such as this can also be installed in existing gear.

Regarding how the device works; It is as WdeanN stated- The arc in the vault becomes a preferred conduction path and the system cannot sustain two arcs simultaneously. The one with the highest impedance will extinguish. Not sure it is technically correct to state the arc in the vault takes energy or current from the first arc. But it does take it from the system causing available voltage to lower and as the first (fault) arc's current lowers, its impedance increases, quickly extinguishing the original fault arc.

This is a brief summary. Hopefully it helps.

Marcelo,
Glad you made it by. I'm sure Jim would consider you a great addition to the arc flash forum.
I hope you stick around and contribute!