Need detectives!

I just completed our annual CT scan of the electrical equipment. One of the hot spots found was a terminal block mounted on a DIN rail. Actually it is among hundreds of terminal blocks on the DIN rail. They are in an air conditioned MCC panel. It is all 480 three phase motor leads. The terminal blocks are A/B 1492 H style. One phase damn near melted into another phase. I was replacing the blocks when I found that all the blocks were covered with OIL! There is a drip of oil at the bottom of the DIN rail. I pulled them all off and wiped them down with contact cleaner. Where could the oil be coming from. I will attach pictures so you get an idea of the layout. These are at the bottom of the panel vertically mounted. Nothing above them have a trace of oil. I have seen drives leak oil from the caps, but these are across the line starters. One of our questionable electricians thought it was leaching out of the plastic due to heat. This is a lot of oil to be leaching out. What do you think???

Just some ideas:

Has anyone gone in with an air gun and blown out the panel?

Does any part of the air conditioning unit have oil in it that may be leaking?

What is in the air? Could the machine have been run with the door open for a while in a misty environment?

What is above the enclosure? Is there an air line with a leak misting oil on the box?

I had a similar issue before. Oil showing up in a junction box on the third level of a multi store system. There was nothing with oil above the j-box. Found a hydraulic cylinder position sensor, on the first floor, with a blown o-ring letting oil flow up the cable to the third level. No oil was visible any other place on the system.

Thanks ndzied1,
The AC unit doesn't appear to be leaking freon, it isn't on anything else. I even thought that it was cutting oil from threading conduit and it was left in the conduit and dripped down the wires over time. The install is 15+ yrs old. I work for the "other" soda maker and we have syrup in the air but no oil. Nobody cleans the panels except for me sad to say! I am at a loss. A phase to phase short would have shut us down for a while. Time = money.

doctord, you must have pulled your hair out looking for that. It almost looks like the terminal blocks were lying in oil before they were installed. My boss suggested that the manufactures might have over lubed the screws and the heat has melted the grease causing it to run. That is a stretch. I pulled some off the shelf in the crib to examine, and none were "pre-lubed".

Are you sure it is really oil and not airborne syrup condensed in the cabinet chller?
Do you use pneumatics in the plant and how much oil do you use in oilers? How much is carried over from compressors?
Maybe you dont have much airborne oil and or syrup mist
BUT
when you consider that the cabinet fans run many (24?) hours per day at X cfm and you get only 1% syrup or oil condensation it adds up.

Dan Bentler

doctord said:

I had a similar issue before. Oil showing up in a junction box on the third level of a multi store system. There was nothing with oil above the j-box. Found a hydraulic cylinder position sensor, on the first floor, with a blown o-ring letting oil flow up the cable to the third level. No oil was visible any other place on the system.

Click to expand...

I have seen similar. On a turbine driven compressor. The instrument wiring ( actually RTD wiring) ran to a junction box that was routinely full of turbine oil. The oil would wick all the way back to the control van 200' or more through the wires insulating jacket. It would cover the terminal strip. We just cleaned it once a year. Never caused any problems. The oil must have had good insulating qualities.

I had a situation where the plasticizer used in the manufacturer of insulation for electric wiring was separating from the PVC and leaking out the end of the conductors. The manufacturer acknowledged that there was a bad batch of PVC in the marketplace about 15 years ago.

Leitmotif, When I first started working there I had a hard time discerning syrup residue from oil. Get a little on your finger and work it under warm water. The syrup will dissolve where oil won't. The air compressors are (relatively) oil free, food grade air is a requirement by AIB. Some of our panels are fed a positive pressure by compressed air or nitrogen. Try working at the bottom of a nitrogen purged panel for any length of time. I was seeing dead relatives!

Mickey, I have heard the same thing from various people but I have never seen it myself. A PVC sheath would make a good conduit. I don't understand the fluid dynamics there but it makes sense. Correct me if I am wrong, but don't they use oil to insulate transformers or is it used to dissipate the heat?

If you are not careful in any nitrogen purged space
YOU will be a dead relative.

Nitrogen is a non toxic inert gas. BUT oxygen deficiency can and will cause you to pass out quickly. If there is no one else around to drag you out and get help you are gonna see the coroner next.

Dan Bentler

Jim, first of all, you are lucky to live in God's country. Any state that puts HD motorcycles and breweries together is a winner. I have family and friends in Ft. Atkinson and Madison.

It really makes me nervous having all that potential energy coated with oil. I have ordered new terminal blocks and I will cut back the wires just to check if there is any oil upstream. I just completed an 8 hour arc flash training seminar and I was ill half way through. The poor guy with his tweeter burnt off was the kicker. Thanks for the help!

spice_miner said:

Mickey, I have heard the same thing from various people but I have never seen it myself. A PVC sheath would make a good conduit. I don't understand the fluid dynamics there but it makes sense. Correct me if I am wrong, but don't they use oil to insulate transformers or is it used to dissipate the heat?

Click to expand...

My guess as to how oil can migrate on the wires in conduit is simple wicking.

For transformers
I would say oil primary purpose is cooling. It of course has to have a very high dielectric.

Dan Bentler

spice_miner said:

Mickey, I have heard the same thing from various people but I have never seen it myself. A PVC sheath would make a good conduit. I don't understand the fluid dynamics there but it makes sense. Correct me if I am wrong, but don't they use oil to insulate transformers or is it used to dissipate the heat?

Click to expand...

Yes Transformer Oil. I used to test that stuff in the Air Force.
We would scoop some out and put it in a device similar to a megger.
Crank it up and watch it arch at about 25,000 volts. This was in the mid 60’s
Probably PCB’s , who knows.

http://en.wikipedia.org/wiki/Transformer_oil

We just cleaned it once a year. Never caused any problems. The oil must have had good insulating qualities.

Click to expand...

any effects on insulation the oil may come in contact with (cable jacket, wires, terminals)? they all need to be oil resistant or i'd expect them to harden and crumble after while.