Clark single phase motor wiring

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info_1marchco

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Hi
Newbie question
I have a single phase Clark Raider compressor that won't start - I have replaced the capacitors and connected them as per the old ones but still no joy
I'm suspecting that the motor is toast
I'm a bit confused by the wiring though
The motor has 2 red wires 1 black wire and 2 blue wires that are connected to the centrifugal switch
Am I correct in thinking the red wires are the line feeds to the start and run windings and the black wire is combined common for both winding
Thanks
 

Spectric

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Is the centrifugal switch closed with the motor not running? The centrifugal switch connects the larger start capacitor to the start winding to provide a larger startup current and higher torque but once the motor is running the switch opens and the start capacitor is taken out of the circuit.

Is it making any sort of noise when you try to start it?
 

guineafowl21

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Has it ever worked, or is it a ‘project’ you’ve taken on? This would determine if the connections are likely to be correct.

Have you checked for physical/mechanical seizure?

Pics inside the connection box and of the rating plate might help. If we can work out what connections there are, we can do a basic test of the windings and switch, if you have a multimeter.
 

guineafowl21

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A quick diagram showing a typical cap-start-cap-run motor, to start things off:

image.jpg
 

info_1marchco

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Hi
Thanks
Was without my phone yesterday so didn't see all your replies
This is a bit of a project, the compressor is at work so I've not got it with me but I've got some photos on my phone I can try upload
I've never seen it work and I don't trust that it's wired correctly either, I just decided to try get it working
I have some basic understanding of electrical systems but I'm not an electrician
It's not mechanically seized and will turn by hand
I've had the motor and the pump apart
The centrifugal switch was stuck open but I've freed it up
There are signs that the motor has got hot at some time and there is rust present
It just doesn't do anything at all when it's switched on
I've got continuity from the plug through the pressure switch and the overload switch to the line in connection on the terminal block
I think it'll be a new motor but I'd like to know it's wired correctly first and the 2 red and one black wire set up is throwing me - is the black wire a combined common or neutral side of both windings?
If so I have continuity on red/black for one of the windings but not both
I'll try post some pictures when I've worked out how to do it
Thanks again for your reply's
 

info_1marchco

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Here are a few photos
 

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info_1marchco

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I know it's not in the best of condition but I like a challenge, it's been stood for about a year and was covered in a combination of over spray and saw dust but it turns ok
 

guineafowl21

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At first glance, the wiring doesn’t appear to be right. There is no live feed to the aux winding, for example. Having said that, there is a complete circuit to the main winding (assuming it’s the red wires), so you should at least be getting a humming noise.

I’d guess an open main winding, since the centrifugal switch was seized, the motor would have been attempting to start using only the run cap, and may have overheated and popped a winding.

Two options:
1. Contact Clarke UK for a wiring diagram and reset to standard form.
2. Disconnect all inputs and caps, leaving only the motor wires, having first noted all their positions. Using a multimeter set on resistance, measure between all combinations of wires and note the values, so we can identify and build up the correct setup. I’ve done this remotely before, so it is possible.
 

info_1marchco

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Hi
Thanks
I was thinking that the red wires were one for each winding and the black a common for both but I don't really know
There's no continuity between the two red wires so if they are the main winding then it's probably popped as you say
But if that's the case then what is the back wire for
I know the blues are the centrifugal switch (which is now closed )
Looking ate the pictures of the copper windings for they look burnt out ?
Thanks
 

Housey210

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The red knob on the black pressure unit is a pull up, on off switch. I trust that is on.
 

guineafowl21

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Hi
Thanks
I was thinking that the red wires were one for each winding and the black a common for both but I don't really know
There's no continuity between the two red wires so if they are the main winding then it's probably popped as you say
But if that's the case then what is the back wire for
I know the blues are the centrifugal switch (which is now closed )
Looking ate the pictures of the copper windings for they look burnt out ?
Thanks
Yes, we don’t know what the wires are for, so I’d be seeking a diagram or measuring between the wires before scrapping the motor. Usually, each element has the same colours for both ends.

If the black wire is a common for both, then that means the motor is not reversible, in which case that common would be made internally and not brought out to the terminal box.

If you’re sure the blue wires are the switch, then one of the caps is across the switch. This means, at rest, that the cap is shorted out of circuit, then brought into play when the motor is spinning, which is backwards of what should happen.

There is some blackening of the windings, but I’d say it’s time to get your multimeter out.
 

guineafowl21

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Draw a diagram of how the wires are arranged currently, just in case.

Disconnect incoming mains wires and caps, then just have the 5 motor wires disconnected and in a row, labelled 1-5 with masking tape or whatever.

Multimeter on ohms setting.

Measure and record resistance between:
1-2
1-3
1-4
1-5

2-3
2-4
2-5

3-4
3-5

4-5
 

info_1marchco

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Ok
Thanks
I'll need to bring the motor home again from work
So it might be a day or too before I get back
I only have a cheap multimeter
But I do have a Fluke Multi tester - am I ok using the resistance settings on this machine instead
Thanks for your help
 

guineafowl21

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My Fluke MFT gives odd results when measuring the resistance of inductive things like motor windings, presumably because it uses a pulsed waveform of similar. Cheap multimeter should be fine.
 

heimlaga

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If a winding is burned one can very often see a bit of soot or some traces of overheating in that spot.

In that case you could rewind the motor but it is a fair bit of work and a bit of a learning curve.
 
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