Electrically vs. Manually operated circuit breaker and arc flash 2

[bdn2004]

We have an 800A, 480V circuit breaker inside of piece of equipment that we are purchasing. According to the arc flash data this breaker will be an arc flash hazard to operate. We're considering installing an electrically operated breaker.

First off is the "electrical operation" referred to the racking in to the bus bar, as opposed to a manual circuit breaker that you manually reset by brute force?. Like how reliable are these? Are there drawbacks to this type of breaker? Are there limit switches or something that assure its made contact?

 

[dpc]

"Electrically-operated" generally means the breaker is closed electrically. Typically, a motor operator or a spring-charging motor is provided. This will require a source of control power, typically (in the US) 120 V ac, 48 V or 125 V dc.

The breaker will have auxiliary contacts to indicate breaker position (open or closed).

It does not refer to racking in the breaker - that is a different matter. Remote racking devices are available for this function to reduce arc-flash hazards.

David Castor

http://www.cvoes.com

 

[Zogzog]

There are also remote switching devices for about every breaker type. An EO breaker is more complex but reliable, problem is , usually the "remote" location is still inside the arc flash boundary. Remote switching allows you to operate it wirelessly from several hundred feet away if necessary.

 

[bdn2004]

Zogzog,

I'm not really following you there...why would the remote location necessarily be inside the arc flash boundary, if it's a remote location? Are you saying we hook up some kind of a wired remote to the front of the breaker, head off some 20 or 30 feet to trip it? Seems like we could mount a permanent pushbutton station outside of the arc flash zone. Is this ever done?

 

[ScottyUK]

Yes, it's certainly done: that's exactly how our HV gear is configured, and we're intending to do the same with the LV gear when it is replaced. A brick wall and a [½]" thick steel blast door certainly beats any flash suit in terms of personnel protection.


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If we learn from our mistakes I'm getting a great education!

 

[TurbineGen]

bdn, what zog is likely referring to is that the control panel for these breakers is often in close proximity. This is often the case in small substation control houses. So therefore the "remote location" is a panel in the same room and only 5 or 6 feet away, sometimes less. Seldom is there anything but free space in between the remote panel and the breaker. This is common in many small substation control rooms where the breakers are on one wall and the controls on the opposite wall.

Your idea of mounting a remote push button has been done many times. In many intallations I have seen they make a small breaker control room that is separate from the room that houses the breakers where the breakers can all be operated remotely well outside of the arc flash boundary.

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If it is broken, fix it. If it isn't broken, I'll soon fix that.

 

[TurbineGen]

To Scotty's point, drywall is not an arc flash boundary. Nothing beats a steel blast door and a brick and mortar wall.

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If it is broken, fix it. If it isn't broken, I'll soon fix that.

 

[Zogzog]

Scotty and TG covered it, you can wire a remote station outside the arc flash boundary, and that is a good idea. But the "remote" switch is commonly placed very close to the breaker, so be sure to spec where you want the panel located if you go this route.

Or you can use a remote switching device, see attached. You can use this on any breaker, switch, MCC< etc that you want to operate from outside the arc flash boundary without modifing your existing equipment. It won EC&M's product of the year.