Do PM Benifits Outweigh Harm???

[StephenSDH]

I was sitting at lunch with a customer who told me they PM their Medium Voltage (30+kv) switchgear every year, along with their lower voltage equipment. Shut down the plant, open everything up, dust out enclosures, exercise breakers, hire a company to test Medium Voltage Transformers Windings.

I read in a previous post that someone smoked all their lighting during a pm, my previous company powered up after a PM and all the AC load turned on at the same time and took out a HV fuse(down for another day). Just read an article ECM about an experienced electrician getting lit up because he didn't know HV switch was backfed. I haven't heard of anything good happening from a PM.

Do you think it is worthwhile doing a PM annually? To me it just seems like more harm then good, both equipment and people. Half the time at my previous company the people doing the PM didn't really know what they where looking for. I believe in infared testing, but I'm not sure about exercising breakers, retightening lugs, messing with the Medium Voltage Gear.

(After bragging at lunch when we got back 800A ground fault and he didn't know how to reset the breaker.:smile

 

[jim dungar]

Per NFPA 70E - 2009, electrical equipment must be PM'ed. See Articles 200, 210, and 225 at a minimum.

If equipment fails just because it was turned off and then back on during a scheduled PM, what would happen after an unscheduled outage and restoration caused by the utility during a storm?

 

[weressl]

I was sitting at lunch with a customer who told me they PM their Medium Voltage (30+kv) switchgear every year, along with their lower voltage equipment. Shut down the plant, open everything up, dust out enclosures, exercise breakers, hire a company to test Medium Voltage Transformers Windings.

I read in a previous post that someone smoked all their lighting during a pm, my previous company powered up after a PM and all the AC load turned on at the same time and took out a HV fuse(down for another day). Just read an article ECM about an experienced electrician getting lit up because he didn't know HV switch was backfed. I haven't heard of anything good happening from a PM.

Do you think it is worthwhile doing a PM annually? To me it just seems like more harm then good, both equipment and people. Half the time at my previous company the people doing the PM didn't really know what they where looking for. I believe in infared testing, but I'm not sure about exercising breakers, retightening lugs, messing with the Medium Voltage Gear.

(After bragging at lunch when we got back 800A ground fault and he didn't know how to reset the breaker.:smile

All equipment needs some maintenance. Some of the old practices are not really meaningful anymore and many new techniques provide better than before results. The maintainers MUST be thoroughly familiar with the specific equipment they serve and also with the expected results. Retightening bolts is a broad term and dependent on the connection, it could be harmful. Excercising breakers is absolutely necessary for mechanical reasons, also properly cleaned and relubricated at the appropriate points. The interval of specific tasks should vary, dependent on the cleanliness and level load - as compared to nameplate load - and the thermographic results.

 

[StephenSDH]

So have you had breakers not reset during a PM? What have you found that offset the effort/risk?

 

[quogueelectric]

So have you had breakers not reset during a PM? What have you found that offset the effort/risk?

Maybe just maybe you will discover a problem with your breakers that dont work correctly. I guess it is better to stick youur head in the sand and ridicule the professional electricians who test and try to avoid an inconvenient outage. Why would you want to find out your largeframe breakers dont work properly. You should wait for a huge fault to determine this and all sit in the dark.

 

[StephenSDH]

better to stick youur head in the sand

I would perfer not stick my head in the sand and learn what the real benefits are to recommend this in the future. It would help if I had some concrete proof of what a PM discovered/prevented, but I have nothing. Sounds like you have nothing to offer either. I'll continue sitting in the dark.

 

[jim dungar]

So have you had breakers not reset during a PM? What have you found that offset the effort/risk?

Yes, last Friday, a paper mill did not come back on-line, after a planned outage.

The offset is a planned outage (spares on hand) versus an unplanned outage.

 

[quogueelectric]

I would perfer not stick my head in the sand and learn what the real benefits are to recommend this in the future. It would help if I had some concrete proof of what a PM discovered/prevented, but I have nothing. Sounds like you have nothing to offer either. I'll continue sitting in the dark.

If you think that I would ever agree to a position like that you will be waiting for ever. It is kind of like someone telling you how oil changes on a car is a waste of time and sitting there waiting for someone to agree with him. Every company is entitled to the degree of reliability of thier equipment yet this costs money. Those with regular pm usually have little to no problems and they pay for this reliability level. The 800a breaker that tripped on ground fault was either set too low which is a condition that I would have picked up in about a second and probably the most likely scenario of how it happened. Or it probably cleared a ground fault doing its job. PM means sending largeframe breakers out for periodic testing to ensure they work.

 

[Doug S.]

A specific example?

A specific example?

I've seen a "simple" sub-cleaning reveal a loose lug. The inspection only needed to be visual, as it had been burning the tap wire. Fortunately we caught it early enough and were able to cobble a temporary repair. If it had burned another two inches the transformer would have needed to be repaired/replaced. For a facility fed from that single sub, that's a big deal. No power in a production facility, for a week, or two is not a good thing.

Also, in another instance, it was found out an MV S&C was bottom fed by the POCO. I was much happier to find this out in a moment of calm and caution.

I've also had gotchas after planned outages. The last plant I was in, we figured an extra 6 - 8 - 10 hours for all the little things that decided not to turn back on. Still well worth the annoyance and cost.

Smoking lights, and blowing a HV fuse are things that happen, but it sounds like who ever was in charge was not using proper procedure or caution.

My 2?
Doug S.

 

[brian john]

I was sitting at lunch with a customer who told me they PM their Medium Voltage (30+kv) switchgear every year, along with their lower voltage equipment. Shut down the plant, open everything up, dust out enclosures, exercise breakers, hire a company to test Medium Voltage Transformers Windings.



(After bragging at lunch when we got back 800A ground fault and he didn't know how to reset the breaker.:smile

I hope it is beneficial, because that is how I have made my money for 30 years. BUT do mistakes happen, sure when the untrained get in there tightening willy nilly, spraying gosh knows what on insulators, hitting equipment with voltages outside it's recommend threshold.. You need trained PROFESSIONALS not a man with a pair of Kliens and a screw driver.

 

[brian john]

so have you had breakers not reset during a pm? What have you found that offset the effort/risk?

proper maintenance.

 

[brian john]

I would perfer not stick my head in the sand and learn what the real benefits are to recommend this in the future. It would help if I had some concrete proof of what a PM discovered/prevented, but I have nothing. Sounds like you have nothing to offer either. I'll continue sitting in the dark.

1. Lubricants (older types) dry out, cleaning and lubrication allows a switch to operate per design. In particular draw out breakers will seize in their cubicle if not regularly removed and service.
2. Cleaning insulator prevents insulators from becoming semi-conductors.
3. Regular meggering allows trending and predictive maintenance can be implemented.
4. Regular testing on circuit breakers insures the protective devices are operating per the manufactures curves.
5. Micro-ohm, ductoring, contact resistance measurement check the conditions of contacts.
6. Re-torque at the manufactures prescribed values for RE-TORQUE can avoid loose connection issues.
7. If you do IR you need an outage to repair the items found deficient during the thermal scan.
8. Then there is oil testing, TTRs, relay testing to name a few all important to insure a safe, reliable electrical distribution system.
9. I have 3 kids in college and a 4th on the way, I have bills to pay.


Now if you would like a list of issues we find I can send you 100's of EPM detailed reports

 

[weressl]

You need trained PROFESSIONALS not a man with a pair of Kliens and a screw driver.

Unfortunately there are more and more of such pseudo-professionals are out there. Some come here to learn........at least.

PS: You meant to say Kleins, didncha.....:smile:

 

[Pierre C Belarge]

Based on the information provided in the OP, it sounds more like people who are not familiar with the procedures actually caused the problems.
Properly trained personnel will not see issues, unless it is unforseen issues.
I am willing to wager that properly performed PM projects have saved a lot more money and anxiety than they have caused.

 

[mayanees]

I have 3 kids in college and a 4th on the way, I have bills to pay.

... on the way???? .... to college I hope or you're gonna be one tired old dude at the High School graduation!!

To the OP, Jim Dungar's comment should have ended the discussion. PM is not an option, it's OSHA/NFPA required. How beneficial it is becomes a moot point.

 

[brian john]

... on the way???? .... to college I hope or you're gonna be one tired old dude at the High School graduation!!

To the OP, Jim Dungar's comment should have ended the discussion. PM is not an option, it's OSHA/NFPA required. How beneficial it is becomes a moot point.

Had my last at 40, she is in Scotland on a foreign exchange and will start her senior year of high school in the fall. One in grad school, one a senior in college and one a sophomore in college.


Laszlo I always screw that spelling up Kliens Kliens.

 

[StephenSDH]

Thanks guys. I don't think most of my customers even have spare large frame breakers laying around, 800+ if for some reason the breakers didn't reset. Preventative maintenance seems to be a growing market along with arc flash and coordination studies. There is probably a need out there for people that know what they are looking for.

PM is not an option, it's OSHA/NFPA required. How beneficial it is becomes a moot point.

This is a broad statement. As far as I know OSHA hasn't adopted the NFPA 70E. yet.

 

[weressl]

Thanks guys. I don't think most of my customers even have spare large frame breakers laying around, 800+ if for some reason the breakers didn't reset. Preventative maintenance seems to be a growing market along with arc flash and coordination studies. There is probably a need out there for people that know what they are looking for.



This is a broad statement. As far as I know OSHA hasn't adopted the NFPA 70E. yet.

That would be 70B.

You are right, OSHA did no adopt ANY NFPA Standard, but recoginzes some as useful in attempting to comply with OSHA requirements. They also make it clear that following ANY of those recognized standards neither will assure complete compliance with OSHA's requirements nor are they the only way to comply.

 

[bobsherwood]

This is a broad statement. As far as I know OSHA hasn't adopted the NFPA 70E. yet

Yes, they have. It's the "General Duty Clause". Lawyers will tell you that it has been adopted.. Better to use it!

 

[realolman]

I think the OP has a valid question.

He asked for specific examples to try to make an informed decision, and there have been precious few examples posted where the benefits saved by PM outweighed the cost. I think an infrared scan is be the most bang for the buck and the least disruption.

I also think there are some things that definately should be done.... operating large switches, breakers etc.

It is certainly not on a par with changing the oil in a vehicle's engine, and I doubt seriously there are too many large frame breakers laying around on the occassion of PM, that wouldn't be laying around anyway.

Sure, there are those who make a living doing this stuff, and sure there are hacks, and one more sure... you'll find stuff, you'll find a whole lotta nothin too. How many of you would be so willing if you were paying the bill?



Dollars spent doing PM << Dollars saved doing PM... I wouldn't bet the rent on it.