Oil-filled combination starters - does anyone have experience using these?

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Isaiah

Senior Member
Location
Baton Rouge
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Electrical Inspector
This plant is very old; nearly 100 years in service, literally. Many of the existing motor starters are mounted on switchracks installed sometime back in the 1950's - CID2 areas. Needless to say, they're in pretty ragged shape, mainly extreme oxidation. I am trying to convince the client these old 'dinosaurs' should be replaced with Nema 7 enclosures, new components etc to meet his own specification but like most clients, he is ultra-cheap,ultra-cautious and very stubborn. Has anyone out there had negative experience with oil-filled combo motor starters?
 
1) The oil is likely PCB laden, if it leaks unexpectedly it's a major HazMat situation, high clean-up costs, long down time etc. Actually you will have some of those costs just to remove them, but it can be done during a scheduled shutdown, as opposed to more costly emergency situation where the added delay in getting anyone to come and deal with it can be very very expensive.

2) The oil must be periodically checked for dissolved gasses etc. as the equipment ages. Not doing so runs a risk of having it cease to function as an insulator. In m y experience people who are too cheap to change out old obsolete equipment are likely too cheap to do proper maintenance as well.

3) If it does fail, nobody has made an oil immersed motor starter in the US in 50 years that I am aware of, so there will be no parts, no like-for-like replacements. Again, swapping it out with a regular NEMA 7 motor starter in an emergency shutdown situation will cost WAY more than doing it now preemptively and being able to shop for, and wait for, a NEMA 7 starter.

All that said, in both situations where I have come across them, neither (cheap) person decided to do the right thing, electing to "take their chances"... One of those resulted in a fire just 6 months after I left.

Good luck...
 
Depending on a lot of variables, it may be more cost effective to relocate the motor control equipment to a nonclassified area than to install NEMA 7 enclosed equipment.
 
Jraef said:
1) The oil is likely PCB laden, if it leaks unexpectedly it's a major HazMat situation, high clean-up costs, long down time etc. Actually you will have some of those costs just to remove them, but it can be done during a scheduled shutdown, as opposed to more costly emergency situation where the added delay in getting anyone to come and deal with it can be very very expensive.

2) The oil must be periodically checked for dissolved gasses etc. as the equipment ages. Not doing so runs a risk of having it cease to function as an insulator. In m y experience people who are too cheap to change out old obsolete equipment are likely too cheap to do proper maintenance as well.

3) If it does fail, nobody has made an oil immersed motor starter in the US in 50 years that I am aware of, so there will be no parts, no like-for-like replacements. Again, swapping it out with a regular NEMA 7 motor starter in an emergency shutdown situation will cost WAY more than doing it now preemptively and being able to shop for, and wait for, a NEMA 7 starter.

All that said, in both situations where I have come across them, neither (cheap) person decided to do the right thing, electing to "take their chances"... One of those resulted in a fire just 6 months after I left.

Good luck...
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Jraef, thank you for this excellent insight. I never would have considered PCB's but you're right! Without a doubt a HazMat scenario. Thanks again.
 
retirede said:
Depending on a lot of variables, it may be more cost effective to relocate the motor control equipment to a nonclassified area than to install NEMA 7 enclosed equipment.
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If this were a 'normal' client I'd say yes. Their mentality is everything has to be treated as Class I, Division 2 - even applies to nonclassified areas. I know, its crazy.
 
Tony S said:
Get rid of them, a new switchboard is the obvious answer. Not the cheap option but the safest.

That said I switched these types of OCB’s for 23 years, as far as I know I’m still alive.


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Haha LOL, I agree Tony! Interesting photos by the way.
 
I fought this battle at my last job. The owner was under the notion run it until it fails and deal with it when it does. The economics of the plant allowed them to do this. Needless to say I made a lot of money during call outs.
 
MrJLH said:
I fought this battle at my last job. The owner was under the notion run it until it fails and deal with it when it does. The economics of the plant allowed them to do this. Needless to say I made a lot of money during call outs.
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Believe me, you hit this nail right on the head!
 
Nothing wrong per se. But the way they actually work as discovered years later is that the arc causes the oil to dissociate so that it creates a small bubble of hydrogen gas that is the quenching medium, not the oil itself. So if you close back in before the oil has time to reabsorb the hydrogen, boom! Also it’s not so much the DGA analysis as it is the amount of burned up oil (soot/carbon). This requires periodic changing of the oil. Which is why I’ll bet it’s technically not PCB containing any more. If however it “never” switches then the PCBs will naturally leach out of the other insulating components (wood, varnish, etc.). As long as you test the oil and change before it reaches 10 ppm, it’s technically non-PCB.

Starters are rare but there are still plenty of load tap changers (current vintage), reclosers, and a few circuit breakers out there. Below 40 KV they have been mostly displaced by vacuum interrupters where possible, and pretty much everywhere else by SF6 equipment. May want to look at GIS such as S&C has a vacuum breaker/contactor with a disconnect and compartmentalizef fuse. The whole thing is in a stainless enclosure filled with SF6 under pressure then plug welded shut for around $40k. Very reasonable for what amounts to GIS grade equipment. Talk about low maintenance/rugged! I have it on good authority that Fort Lejeune uses several of these.
 
The top photograph had a “vent header” where the gasses were directed outside the switchroom.

Close a manual OCB on to a fault and it starts grumbling it’s time to run, fast!!

It only happened twice and now I’m retired, it won’t happen again.
 
paulengr said:
Nothing wrong per se. But the way they actually work as discovered years later is that the arc causes the oil to dissociate so that it creates a small bubble of hydrogen gas that is the quenching medium, not the oil itself. So if you close back in before the oil has time to reabsorb the hydrogen, boom! Also it’s not so much the DGA analysis as it is the amount of burned up oil (soot/carbon). This requires periodic changing of the oil. Which is why I’ll bet it’s technically not PCB containing any more. If however it “never” switches then the PCBs will naturally leach out of the other insulating components (wood, varnish, etc.). As long as you test the oil and change before it reaches 10 ppm, it’s technically non-PCB.

Starters are rare but there are still plenty of load tap changers (current vintage), reclosers, and a few circuit breakers out there. Below 40 KV they have been mostly displaced by vacuum interrupters where possible, and pretty much everywhere else by SF6 equipment. May want to look at GIS such as S&C has a vacuum breaker/contactor with a disconnect and compartmentalizef fuse. The whole thing is in a stainless enclosure filled with SF6 under pressure then plug welded shut for around $40k. Very reasonable for what amounts to GIS grade equipment. Talk about low maintenance/rugged! I have it on good authority that Fort Lejeune uses several of these.
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Very interesting post! I never would have guessed hydrogen gas was a key component and may also may cause an explosion, this is definitely going on my list! Do you know of an incident where this has occurred?
 
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petersonra said:
that would be the best option if it is doable.
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Agreed 100%. I'd prefer to remove all SWRKS and add MCC's but knowing this client, he'd see this as outrageous and unnecessary cost. The best I can hope for is 'replace in kind' with updated equipment.
 
Isaiah said:
Very interesting post! I never would have guessed hydrogen gas was a key component and may also may cause an explosion, this is definitely going on my list! Do you know of an incident where this has occurred?
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Yes. Everyone that has this equipment at one time or another eventually finds out the hard way.

My first experience is I kept getting back “high soot” in my oil samples on the plant main breaker. I suggested we change the oil at the first cast iron pipe plant in the US around 2006. The plant maintenance manager said they always have carbon and this is normal. Well some anyways. I had no experience with them so we went with the voice of experience.

Until one day when one of the three tanks shot oil everywhere that lit on fire and tripped the utility.. the center tank was destroyed not enough pieces to forensic anything except that it arced . unrepairable of course. So we located an SF6 breaker nearby. Called upper management and got permission to change it out. 12 hours later we were back in business.


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paulengr said:
Until one day when one of the three tanks shot oil everywhere that lit on fire and tripped the utility.. the center tank was destroyed not enough pieces to forensic anything except that it arced . unrepairable of course. So we located an SF6 breaker nearby. Called upper management and got permission to change it out. 12 hours later we were back in business.
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I'm sure they were glad of all the savings in waiting for an unplanned outage to replace the breaker. Or maybe not ;).
 
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