Arc Flash Incident Energy Mitigation

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Wingrider

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We have a few data centers for which I am the main consultant. The main question about arc flash mitigation pertains to, 'When is an arc flash study required on an existing building?' 'What mitigation must be applied to low (480 volt) and medium (12.47 kV) voltage switchgear?' We have several rackable circuit breakers that exceed the 40 cal/cm^2 incident energy level. Contacting the manufacturer, GE in this case, we were presented with three options; Remote Racking Operator (RRO), Entelliguard trip units, and an ArcVault. The RRO is about a tenth of the price of the other two solutions. The Entelliguard unit requires the operator to make a coordination change from Operations to Maintenance mode, which removes the time delay. The ArcVault is a passive device that extinguishes the arc in a remote vault. Will the RRO meet the letter of the law?
 
I don't see a problem with the cheap option unless you are doing this on a regular basis.

we got a document from AB today advertising their new MCCB with the maint input.

I am thinking about this and trying to decide why anyone would put one on a combo starter, or even an MCC bucket. I could see using it as a feeder breaker out of an MCC, but I am having a hard time seeing the utility of it anywhere else.
 
Appease the Facility Manager

Appease the Facility Manager

All these comments assist in coming to the obvious conclusion, that it meets the intent of the code to utilize the cheaper solution with the RRO. My main problem is the Facility Manager insists on presenting scenarios where the RRO will not meet the requirement, such as, IR pictures of the main bus. This will apply the incident energy of the transformer main ahead of the bus, which will supply incident energy in excess of the 40 cal limit. I don't see how utilizing the entelliguard will correct this issue.
 
IMO, if it is not suitable for all your needs then it is not suitable.

The Entelliguard option would need to be installed upstream of the racking point to do you any good.
 
The solution

The solution

Ahh, there is the solution hidden within the comments. The RRO is suitable for general maintenance issues where a breaker with high incident energy is required to be racked out, but use the Entelliguard on the units feeding the transformer to the bus. Then we can reduce the initial cost of installing several dozen of the entelliguard trip units, and only install a few of these expensive items where the RRO does not fit the bill.

Thanks guys.
 
Wingrider said:
Ahh, there is the solution hidden within the comments. The RRO is suitable for general maintenance issues where a breaker with high incident energy is required to be racked out, but use the Entelliguard on the units feeding the transformer to the bus. Then we can reduce the initial cost of installing several dozen of the entelliguard trip units, and only install a few of these expensive items where the RRO does not fit the bill.

Thanks guys.
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Seems you have GE blinders on. There are many remote racking and switching systems on the market, some are much better than others, I recommend you look around, ask around other datacenters, and get demos of a few different ones before picking that option.

Same with maintenence switches, nothing wrong with Entilligaurd but there are some other units just as good for a fraction of the cost, and often they can be used on any breaker, not just a few types.

Best solution for IR is IR windows, takes arc flash out of the equation or better yet install IR monitors (Standard datacenter design feature in the UK) in your LV gear and PD sensors in your MV gear.

Lots of solutions out there, I have been doing arc flash mitigation projects for 15 years, well before most people even heard of the 70E.
 
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