Production resetting protective relaying

[Thedroid]

As the subject says, production resets the relays without any thought about a downstream fault. This is on 4.16 GE switchgear from the 50's. Faults are uncommon, but when there is one the relays are reset, and the breakers are closed several times before an electrician is called. We don't have 24hr coverage, but someone would be willing to come out and check the circuit before closing the breaker. We had a large motor go to ground and it tripped the feeder. This was in the middle of the night, and production reset the breaker and tried the motor 4 times before calling an electrician. We also had an animal find its way into a 4.16 fused disconnect, and again the breaker was closed several times before anyone was called. All three fuses opened eventually, and cooked the spring clips also. This is unacceptable in my opinion, and I hope to be able to change the standard procedure soon.

What is the common practice in large industrial plants? Surely this couldn't be commonplace. I would like to try to find some general safety guidelines concerning this matter.

 

[cranky108]

We just fire people who close breakers without inspecting the circuit. Try it, it works well.

 

[Thedroid]

If I had the authority I would. I'm just the guy who has to come out and fix the problem after the smoke has settled. Management seems open to suggestions about some type of policy to replace the lack of one, and I'd like some input on how it's done elsewhere.

 

[cranky108]

A company I workd for in the past had the same problem. Then the managment got a backbone, and problem solved.

 

[electricpete]

We have mostly electromechanical relays. Sometimes there are some subtle clues that can be gained looking at the flag, flag lever, plungers, disk position etc. So it is a strong preference that Operations call electricians to inspect the relay to retrieve any intelligence before resetting any relays on 4kv LC's and above (they can reset overloads on 460v MCC's once before calling electricians.).

Generally our operators follow this practice. But no-ones perfect.


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[Thedroid]

We use electromechanical relays also, and I agree that its important to see if it was time or instantaneous, and especially ground. I'd just hate to see someone hurt, or for the plant to be damaged beyond repair.

 

[dpc]

It's a bad but common practice for the operator to try closing the breaker back in once. That in itself is a bad practice. But to close back in multiple times without attempting to locate and clear the fault should be grounds for termination, or some type of disciplinary action.

On the other hand, relay targets should be reset before the breaker is closed back in. The targets should logged in the log book.



David Castor

http://www.cvoes.com

 

[Thedroid]

Targets are reset, but there is no log.

 

[cranky108]

If you were to replace the relays with microprocessor relays, then you would have a record.

I once found control switchs with keyed handles, which I tried to use in breakers as the maintenance switch.

 

[Thedroid]

That's something we can look at in the future, but the old GE relays we use are still working without any trouble. I'd just hate to have an incident due to no policies regarding the big breakers.

 

[cranky108]

Note that in reporting problems, there is sometimes a desire of the reciever to kill the messanger.

Be careful.

Depending on the politics, it maybe easer to justify fixing the problem of old relays.

 

[Thedroid]

Good advice. Politics can get ugly. Don't large plants usually have policies for these things? They can't all be like the wild west.

 

[marks1080]

Well run plants do.

I have to say I was surprised when reading your posts at the (lack of) procedures being used.

I've noticed since the economic collapse a lot of industries are cutting costs wherever possible to keep from being shut down or having the plant moved to another region. Your issue seems to have been an on going problem though.

Closing breakers into a fault puts serious stress on equipment. Doing this multiple times in a short time frame will shorten the life of your equipment as well. Maybe you can find some information to support this for your report to show the long term dangers/costs associated with poor procedures.

Don't put yourself in the middle of a political issue in case things get ugly. State the facts only. Try not to mention specific personnel who have been involved with these poor procedures.

Mark

 

[oldfieldguy]

Most of the facilities I've worked in had very specific policies about what operators (production department) could do in a substation/switchgear room. Resetting flags on relays was a no-no.

Further, on motor protection, we commonly segregated some faults ((ground fault, instantaneous overcurrent, phase imbalance, motor differential) to operate an 86 device lockout relay, while motor overload could be reset for a restart. Operators were told specifically NOT to reset the 86 device because that was NEVER an indication that they'd overloaded the pump/compressor/whatever, i.e., process-related, rather 86 operation indicated potentially serious electrical faults which had to be investigated before a retry.

In training I presented on new equipment installations I represented this as the difference between a rebuild (expensive) versus a replacement (VERY expensive), plus I emphasized the dangers to personnel and equipment if they kept hitting a faulted cable or motor or transformer with voltage.

I'm not saying that these words were always heeded, but that's what we did.

old field guy