Remote racking great save

[zog]

On Saturday, May 23, about 5pm the CBS ArcSafe RRS-1 was involved in a severe arc flash incident. The incident occurred while racking in a closed Siemens GMI breaker with a faulty interlock. The RRS-1 had radio remote and was being used so that the operators were in another room when the arc flash happened and there were NO injuries of any kind. The RRS-1 was used after the arc flash incident to remove the damaged GMI from the cell for evaluation. The RRS-1 was not severely damaged and is still in useable shape. The operators on site that day said they were positive that lives were saved that day.

 

[Buck Parrish]

Amazing ! your lucky. Did that happen from just turning the switch?

 

[zog]

Amazing ! your lucky. Did that happen from just turning the switch?

No, racking the breaker in. I wasnt there, this is a utility that is a client of mine.

 

[mxslick]

Wow, a graphic example of how proper equipment used correctly can save lives. Great pics and thanks for posting. I do have questions though:

The incident occurred while racking in a closed Siemens GMI breaker with a faulty interlock.

I take it the bold points go together? As I had thought it was supposed to be impossible to rack in a closed breaker? Which in this case means the arc initiated because the breaker's studs were picking up load?

 

[zog]

I take it the bold points go together? As I had thought it was supposed to be impossible to rack in a closed breaker? Which in this case means the arc initiated because the breaker's studs were picking up load?

Yep, they are relayed, there is an interlock that is supposed to prevent tacking in the breaker closed, but it failed. Further investigation found 4 more out of 20 breakers had the same damaged interlock. If you are interested in the findings of this GMI issue you can email me.

 

[cornbread]

In all my years of racking stuff in with no problems, I had my doubts if remote racking was worth the cost and effort. Thanks to this post I can see the error in my thinking. Many thanks for posting this.

 

[Smart $]

...this is a utility...

I have witnessed the remote racking process (from remote location, of course ) in a couple AEP power plants, but never with any problems other than the remote racking machine not responding to controls. The remote racking procedure is defnitely the way to go.

 

[Cow]

In all my years of racking stuff in with no problems, I had my doubts if remote racking was worth the cost and effort. Thanks to this post I can see the error in my thinking. Many thanks for posting this.

Zog will love you for saying this!!

 

[cadpoint]

:roll: Yes Zog, We Love You Man, could you dumb it down for the Masses!

 

[zog]

This is a 15kV Vaccum breaker, if you rack it in the cell when it is closed you get an arc flash when the stabs hit the bus, it is like dropping a screwdriver phase to ground, but a bigger boom. There is a mechanical interlock on all draw out breaker called a "Racking interlock" that prevents you from racking on or out a closed breaker, in this case that interlock failed, and is a common problem (As we concluded from our forensic analysis on the design) on this breaker type.

 

[Cow]

Isn't there a way to check the interlock beforehand since the breaker had not been installed yet? I can understand not being able to check when withdrawing it, as it's installed and inaccessible.

Finding out the hard way on an expensive piece of gear like this just doesn't seem to make much sense to me?? Just makes me think there must or should be a way to check it first...

 

[jeremysterling]

Isn't there a way to check the interlock beforehand since the breaker had not been installed yet? I can understand not being able to check when withdrawing it, as it's installed and inaccessible.

Finding out the hard way on an expensive piece of gear like this just doesn't seem to make much sense to me?? Just makes me think there must or should be a way to check it first...

I agree. There is a "closed" indicator, right?

I will ohm out an open single pole 20 amp breaker before I screw it to a live bus. You can ohm the stabs on your breaker, right( if you lift control wires)?

 

[zog]

Isn't there a way to check the interlock beforehand since the breaker had not been installed yet? I can understand not being able to check when withdrawing it, as it's installed and inaccessible.

Finding out the hard way on an expensive piece of gear like this just doesn't seem to make much sense to me?? Just makes me think there must or should be a way to check it first...

The interlock is in the cell, not on the breaker in this case. So you need to open the cell and look inside, wearing arc flash PPE, so they missed it. They had racked about 100 of these the previous few days for the outage so it was overlooked, you know how it is when you do something over and over.

 

[zog]

I will ohm out an open single pole 20 amp breaker before I screw it to a live bus. You can ohm the stabs on your breaker, right( if you lift control wires)?

I dont know what "Ohm out" means. But this breaker had just had a Contact resistance test, insulation resistance, overpotential, and vacuum bottle intergity tests done. Just after doing 100+ of them they forgot to open one after testing.

 

[Karl H]

I saw one of these devices a couple of weeks ago at a plant
I'm surveying. The plant manager made a comment of how
it was a waste of money. I informed him that he should watch Arc-Flash
videos and he just might re-evaluate his opinion.

 

[eric9822]

We have a remote racking device that we purchased over a year ago and it is still sitting unused. Everyone seems to think it was a waste of money and it will take too much time to use. Thanks for posting this. I may be able to get some people to see the value of this device now.

 

[zog]

Thanks for the comments, here is some more info on the subject. I will be presenting this at 10 conferences this year, see you there.

http://www.remoterackingsolutions.c...ng-and-switching-for-arc-flash-mitigation.pdf

http://www.remoterackingsolutions.com/downloads/Arc-Flash-Mitigation-paper.pdf

 

[SEO]

Zog very good information! Thanks.

 

[richxtlc]

Sorry I'm a little late in commenting on this item, I've been on vacation with the grandchilden. The remote racking device is a great idea and I promote it to all my clients when I review operating procedures. The device is intended to prevent injuries in the event of failure of the insulation of the breaker or the bus connections as the breaker is racked-in or out.
It is not a substitute for failure to follow correct operating procedures when performing a rack-in or out of a circuit breaker. There is a semiphore OPEN/CLOSE indication on all breakers, it obviously was not looked at prior to performing the operation. All procedures for performing operations on a circuit breaker require the operator to verify that the breaker is in the OPEN position prior to inserting it into the cubicle. The interlocks are there to trip the breaker if the other indications are faulty and for those people who do not pay attention to the breaker indications.
The excuse of racking in many breakers over the previous several days is no excuse for pool operating practices.
If the operator would have followed procedures there would have been no arc flash. Safety, not speed is the first consideration.

 

[zog]

Sorry I'm a little late in commenting on this item, I've been on vacation with the grandchilden. The remote racking device is a great idea and I promote it to all my clients when I review operating procedures. The device is intended to prevent injuries in the event of failure of the insulation of the breaker or the bus connections as the breaker is racked-in or out.
It is not a substitute for failure to follow correct operating procedures when performing a rack-in or out of a circuit breaker. There is a semiphore OPEN/CLOSE indication on all breakers, it obviously was not looked at prior to performing the operation. All procedures for performing operations on a circuit breaker require the operator to verify that the breaker is in the OPEN position prior to inserting it into the cubicle. The interlocks are there to trip the breaker if the other indications are faulty and for those people who do not pay attention to the breaker indications.
The excuse of racking in many breakers over the previous several days is no excuse for pool operating practices.
If the operator would have followed procedures there would have been no arc flash. Safety, not speed is the first consideration.

Agreed, and the procedure did say to check, but it was missed. People make mistakes, and equipment can give false indications. Read slide 31 of this http://www.remoterackingsolutions.c...ng-and-switching-for-arc-flash-mitigation.pdf