86 Relay Lockout vibration trip?

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stonecitysub

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Situation on hand; A relay panel in substation house was being cut to fit in a bigger relay with a sawz-all. The metal was not very hard and the sawz-all handled it with ease and not much vibration. Test switches were pulled on two of the three SEL 501 Over Current relays on the same panel. The lockout that rolled was about 3 feet away from where the cut was being made. The owners are claiming that the 86 tripped mechanically due to the vibration from the saw. Myself as well as some few engineers and other techs I've talked to think it is more likely that there is a loose wire or connection somewhere on the 86 that got wiggled and made/lost contact and that was the problem.
Has anyone seen a situation like this before? any other suggestions or other opinions? Thanks.
 
I have physically manipulated the latch lever on some 86 relays during testing. It does not take too much effort. Still I think it would take a good jostle from a saw. It is possible though. I don't think a wire coming loose would cause it unless it then came in contact with the DC source.

Are you able to inspect the relay? Look on the back for the latch lever that is operated by the solenoid. You can manipulate and get a sense for what kind of force is required to unlatch it. Did you check for loose wires? If there are no loose wires I would bet it was from vibration.
 
One other idea:

If the contact on the SEL-501 protective relay associated with the 86 is set up as fail safe a power glitch on the 501 power supply inputs may have caused the trip. This is more in line with the loose connection theory.

Modern 86 lockout relays operate on very low energy, so mechanical vibration is not to be discounted.
 
When the 86 is reset I almost can't physically close it by hand. This 86 has a coil to electrically trip it. We also have an identical extra 86 with the coil on it and no one has yet to shake it violently enough to trip it. Thank you for all of your input. I'll also check the back of the 501 for loose connection. Some gents are also checking into the event file on the GE G60 line relay to see if there was anything else funky happening in the yard.
 
An 86 relay is just a lockout device to prevent remote closing due to a relay trip. It should never trip itself. It must have a trip input from another relay such as a differential or sudden pressure relay. Most 86 relays I've seen are mechanically latched. I suppose a very high vibration could release the latch, but I've never seen it. They should not be hard to reset. If they are as hard as you say, I'd say you have a spring problem. We did have some on our Uptegraff transformers that were solid state, but were really just latching relays. They reset themselves after a fault if DC was lost. Not too good when it's supposed to be a lockout. Replaced with Electroswitch. In my opinion, GE was the best, but I don't think they make 'em anymore.
 
One point that was not mentioned is if there are older induction disk relays ( 50/51, undervoltage, bus differential, etc) in the lineup then it is possible that the vibration caused one of them to trip the 86 LO device. Some relays will send a trip signal by the opening of a contact which makes it very sensitive to vibration. I have seen LO's trip by banging or slamming the door shut on the older switchboards to get the door to close.

One last thought, if the LO device is old and the latching mechanism is worn out then it may need to be replaced.
 
meternerd said:
An 86 relay is just a lockout device to prevent remote closing due to a relay trip. It should never trip itself. It must have a trip input from another relay such as a differential or sudden pressure relay. Most 86 relays I've seen are mechanically latched. I suppose a very high vibration could release the latch, but I've never seen it. They should not be hard to reset.......
Click to expand...

My post wasn't clear, sorry. It is easy to reset, after it is reset is when it is almost physically impossible with your hand to trip it. Thanks for your input!
 
ATSman said:
One point that was not mentioned is if there are older induction disk relays ( 50/51, undervoltage, bus differential, etc) in the lineup then it is possible that the vibration caused one of them to trip the 86 LO device. Some relays will send a trip signal by the opening of a contact which makes it very sensitive to vibration. I have seen LO's trip by banging or slamming the door shut on the older switchboards to get the door to close.

One last thought, if the LO device is old and the latching mechanism is worn out then it may need to be replaced.
Click to expand...

There are a 2 KD10's for Line Diff 6 panes away or so, and those weren't flagged, pretty sure those weren't the issue. Those were taken in consideration before the project was started. No induction disk relays, however.
 
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