Earthing a Compressor - Earth leakage issues??

[kayl]

I have been trying to get this New compressor 3/4HP horizontal Rotary Low temp rotary going. I have been having issues with Earth leakage though.
Ie if i dont ground the compressor it will run, but touch the compressor, or copper tubbing you get a nice little zap. Then when i plug in my grounded load tester the hole mains trips.
If i ground the compressor the unit trips as soon as its plugged in.
I took a voltage meter and there seems to be 190V AC between earth wire coming from the mains lead and the compressor very dangerous.


So my question is what causes this and how can i fix it guys.
I have cascades to build and looking at ordering more of these compressors, but want to get this one going first.

[TopherTony]

Sounds like a short in the compressor's wiring, but I don't know how to fix it. The entire casing is of the compressor has current running to it? If you ground it, all the electricity that would be used to run the comp dissipates, so you have to fix the short before trying anything else. Probably just an isolated issue, and wouldn't be encountered if you ordered others.

[jinu117]

Check compressor contacts (all 3 of them) with meter to ground (or shell of compressor) on resistance. It should read infinite. If you have megometer better yet.
If there is any resistance you read, need to toss compressor away. Winding is in problem and there is nothing you can do about it.
Good luck pal.

[kayl]

thanxs for that guys, ill check terminals to compressor tonight.

this is what i measured last night between terminals

[SexyMF]

You need an insulation resistance tester. Sounds like the compressor is faulty.

[star882]

Double check to make sure it's not just a pinched wire or something simple like that.

[kayl]

i checked the compressor terminals to the compressor and they all read higher thatn 20M ohms so it seems that the compressor windings are ok??
now im really confused, have to check their wiring inside the box next.

Double check to make sure it's not just a pinched wire or something simple like that.

how do you mean pinched wire?

[jinu117]

20M ohm isn't that great of indication but better than finding some resistance after all (Hence the need for megometer or insulation tester as mentioned)
For time being, let's assume that isn't the source of leakage and time to look for any circuit that has some resistance with parts you touched (ground)

[star882]

Disconnect everything from the compressor and connect only one terminal of the compressor to hot through a night light bulb. Connect the case to ground.

[TopherTony]

It doesn't matter what the other readings are. If there is any current going from the windings to the shell casing of the compressor, there is a short and unless this issue is addressed, the compressor should not be used. Have you checked this yet? If there is INF ohm resistance then continue on, and sorry for the intrusion. :P

[Xeon th MG Pony]

you know I read this, and started thinking why dont you have a electrical/wiring book there? Ground fualt testing is the easist thing in the world! As is testing for a shorted compressor!

Come on guys if you are playing with this stuff learn A/C wiring and testing!

[kayl]

you know I read this, and started thinking why dont you have a electrical/wiring book there? Ground fualt testing is the easist thing in the world! As is testing for a shorted compressor!

Come on guys if you are playing with this stuff learn A/C wiring and testing!

true.


Turns out the china man wired this unit weird.
ya would think that the green yellow wires with connects like below are ment to connect to ground.
Well they also linked them to the caps
So didnt connect one of the ground and it works fine now
thanxs all for help

[SexyMF]

I'm not convinced you have wired it correctly. What is the model number for the compressor?

[kayl]

I'm not convinced you have wired it correctly. What is the model number for the compressor?

It came wired, all i had to do was connect AC and ground leads.
THis is a wiring digram of how it came wired.
Ill scan their drawing monday and load it.
Also the compressor and model number

[{.bLanK} GoD]

ya would think that the green yellow wires with connects like below are ment to connect to ground.

Not necessarily.
You cannot assume any particular colour wire inside an electrical appliance to be what is should be according to our electrical regulations.
Yellow use to be common use for three phase wiring here, it has now been replaced by white. I can't see any green on those wires. Looking at them i would assume they're live.
Even a green or yellow/green wire can not be assumed an earth inside an appliance.especially if it has come from china/taiwan etc.
The other end of the ring terminals you are holding in that photo, where were they connected? To the compressor casing? That would be a short circuit to ground.
Keen to see that manufacture wiring diagram.

This is a good example where they have used a green wire for a live conductor.
When you have fixed it, make sure you test your grounding resistance with an Ohm meter.

[kayl]

I have been in contact and they have given me a English pdf for the compressor. Turns out those yellow wires are for the pressure switch not the earth.
Heres the wiring digram for the Lanlai Compressor HQHD series.

[jinu117]

Yeah... yellow sometimes do get used for controls red and green too ehehe.