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Hello,
well, I'm not an electrician by any stretch but I do know how to wire a plug, use a multimeter and ask for help when I'm stuck.
Currently I'm trying to trace faults in a 3hp single phase 240V compressor motor - I bought the unit really cheap but it looks like the Artful Bodger has been there before me. The unit seems to be missing the thermal overload protector switch and the wiring to the connector block (motor windings and start and run capacitors looks odd - the live wire is connected to an otherwise empty terminal meaning no live feed going anywhere at all - that connector post has nothing else connected to it. I believe that the overload should connect between that and somewhere else on the block.
Anyway, too early for me to be asking questions just yet, I need to research some more and then come back with questions if I can't find the answers. Hopefully this forum will be a very useful resource.
Cheers
 
Welcome to the forum mate.
Draw up how the motor is wired up and post it on here.
 
Welcome to the forum mate.
Draw up how the motor is wired up and post it on here.


Cheers, I will do, unfortunately the it's very hard to read the terminal labels on the connector block. I'll take a picture and post that up here, maybe that will help.
(I think I might have accidentally just created a quoted conversation in the forum - I'm not used to this particular forum version - sorry)
 
Cheers, I will do, unfortunately the it's very hard to read the terminal labels on the connector block. I'll take a picture and post that up here, maybe that will help.
(I think I might have accidentally just created a quoted conversation in the forum - I'm not used to this particular forum version - sorry)

No worries. You just personally replied to me rather than the forum.
 
Here's some pics of the connector block:

https://i.Upload the image directly to the thread.com/vJqEl9B.jpg https://i.Upload the image directly to the thread.com/WBCPrtA.jpg https://i.Upload the image directly to the thread.com/TuNb0kB.jpg https://i.Upload the image directly to the thread.com/ltU3YZV.jpg

The top image is probably the most helpful as it shows the whole layout from above. The brown at top left is the live feed and as I mentioned, there's nothing else connected to that post.
Wires coming from the motor itself as follows: blue and red on the LH side, red to the middle connector - nothing else connected here, blue to the bottom left post, brown from the start capacitor connects here too. On the RH side, negative from supply connects to top right with link visible to centre post. Brown from run capacitor connects to middle post too. and blue from this capacitor to bottom left. Motor connectors this side - there are three on this side, Red, Blue and Black, red to top right, blue to middle, black to bottom right. Thus bottom right has black from motor, blue from start and blue from run capacitor. middle has blue form motor and blue from start capacitor. top has negative from supply and red from motor. Eart is connected directly to motor housing.

I previously mixed up the start and run capacitors so I have now amended the above text to correct this. Start is the blue (200uf capacitor, Run is the white 65uf one)
 
Last edited:
I'm guessing here but I suspect that the thermal protection cut out should connect from the live supply to the middle terminal on the LH side. The thermal protection cut out is missing but looking at the cover for the motor it should have one - there are thread marks from where it should be fitted in the hole provided for it and there was obviously something connected there before. Clearly with live currently connected to an otherwise empty terminal not much will happen.
 
as above.try connecting the Lin to the terminal below it with a temp link. this will have the effect of bypassing the missing thermal overload. give it a flick of power. if it runs, then it's then just a case of replacing the missing overload.
 
as above.try connecting the Lin to the terminal below it with a temp link. this will have the effect of bypassing the missing thermal overload. give it a flick of power. if it runs, then it's then just a case of replacing the missing overload.

OK, I'll give that a whirl and report back.
Cheers
 
Well, good and bad news. The bad news is that trying the wiring mod didn't make any difference. That eliminated one reason. I then continuity tested the motor, one winding is infinite resistance, the other is zero.
I removed the motor end plate and found the good news - I now know why it won't run:
https://i.Upload the image directly to the thread.com/qvJzW1b.jpg

It's cooked itself
 
Welcome to the forum!

I had a few issues with my compressor recently, the pressure would keep building and the pressure-sensor wouldn't cut the motor, resulting in the pressure-relief valve blowing it out.

Personally my solution has been to stay with the compressor constantly, manually switching the motor on/off - which is admittedly pretty boring and unhelpful to be honest.

Therefore I'm currently working on a project using Arduino, which measures the air-pressure using a transducer, converting the output to logic-level using a simple voltage-divider; then using a solenoid to turn on/off the motor as necessary.

I'll admit it's over-the-top, but I've enjoyed the project!
 

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