How to Check The Winding Resistance of a 3ph Compressor
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- Опубликовано: 22 июл 2021
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The first step is to always be safe when using an electrical meter. When checking any compressor winding make sure you lock out and tag out the unit before any work is done. Make sure you always verify there is no voltage at the compressor before you remove the leads.
Here are the steps in checking the windings of a compressor:
Step 1: Read the compressor manual for that compressor to understand if there are any special safety devices that can affect the windings
Step 2: Lockout/Tagout the compressor and unit
Step 3: Verify there is no power at the compressor
Step 4: Remove wire leads or molded plug from compressor
Step 5: Find out what the resistance should be on Copeland Mobile for that model of compressor
Step 6: Put multimeter on ohms
Step 7: Check and write down resistance from L1-L2, L1-L3, L3-L2
Step 8: Check resistance from L1 to Compressor Ground, L2 to Compressor Ground, L3 to Compressor Ground.
Step 9: Compare findings to actual from Copeland Mobile
Step 10: If compressor windings open make sure to let the compressor cool as a safety device or the overload could be open
Step 11: If you determine the compressor is failed, now its time to find out what mechanical failure caused it
Check out this Copeland Electrical Troubleshooting Chart - climate.emerson.com/documents...
Download the HVACR Fault Finder app to better your troubleshooting skills - climate.emerson.com/en-us/too...
Megohm Values of Copeland® Compressors - webapps.emerson.com/online-pr...
Thanks Trev. I've come across that myself 👍
It does happen. Thanks for sharing
Just as I take a break from SkillMill Testing Compressors section, here you are going over bad windings lol. HIPOT Test is new to me. Researching it now. Great info as always Trevor! Thanks!
Yeah check it out. The basic principle of each are a megohmeter, measures insulation resistance. A hipot tester measures leakage current a more expensive way to check windings.
Could you do an indepth on how unloaders work. Also and in depth on digital compressors would be awesome
That is a great idea. I will get some up for everyone.
Excellent content I've got two three-phase compressors right now that are grumbling not wanting to come on I think they were single phase 11 ohms of resistance through each leg
Match it to the compressor manufacturers specifications
Thank you Trevor for your uploaded videos; In the field, how would I detect that failure without a mega meter?
Really these are the few cases you would need one. A very good multimeter can give you a good idea.
How much for hipot tool vs a fieldpice megohmeter?? Thx for the nice quick video keep up for more please😊
Great question. It would be best to search in your local area for pricing.
Trevor, great video. I can't really see the model of the fluke meter you are using here, but it looks like a 376? The reason I'm asking is because I just had a weird call I ran yesterday - it was a Trane CSHA scroll compressor with a tripped breaker. Using a Fluke 376FC I found the resistance to be 54k ohms from each leg to ground with all wires disconnected, but leg to leg was normal, 1.4ohms equal. Out of curiosity, I checked the other compressor in the tandem set and found similar readings. Then, I checked the final compressor in its own circuit and had about the same. I broke out my Fluke 87V and found it reading >2Megohms. Wired them back up, reset the breaker and they all ran like champs with normal current and voltage. I thought maybe it was my battery in my meter possibly, but I have talked to several techs over the last few days that seem to have similar stories and when I asked what meter they said the 376. Do you have any thoughts on this??
Sorry I do not. I have used many meters over the years but I always found myself always going back to Fluke. I would call their technical support line 1-800-873-5853 (NA) Good luck.
What was the resistance to ground when measured with the VOM?
Thanks for the question. I do not remember.
3 phase compressor with a 2 stage would have same ohms reading if it were 1 stage?
I believe so. It is best to go to the manufacture of the compressor and check their fixed model vs their 2 stage model and see. It is my understanding that Copeland ZP & ZPS scrolls will have the same or similar stator in it.
thanks, but i hvent received free course in my email, thanks alot for usefull vedio
Find courses here refrigerationmentor.com/upcoming-courses/
@@RefrigerationMentor thanks