Cap start motor wiring

[kong]

Hiya guys, I have a very old motor, it is capacitor start, single phase AC, reversable. How do I wire it up?!

Here's some clues, wish I knew what I was looking at, but I am a dunce at this. It has 6 wires coming from the insides of the case, 2 Red, 2 Yellow (one with a green dot painted on and one with red paint) and 2 green. The capacitor has 2 wires also, so 8 altogether. On the terminal block, there are two input connectors, L and LE, so I take it LE is neutral. No where to earth this thing, so I will just attatch earth to the casing. Unfortunately most of the wires are disconnected, so where to start? Any ideas?!

[Al_The_Man]

From the sound of it you will probabally have 1pr start winding, 1pr run winding, 1pr centrifugal switch and 1pr cap.
Test the individual pairs for resistance, if all ends are disconnected, there should be no continuity between different pairs.
The run winding, which hopefully will show the highest resistance compared to the start winding, the switch should show dead short (very low resistance) and the cap of course should show open.
The run winding will be permantly connected across the 240, the cap, the switch and start winding will all be in series across the 240 also.
All conductors should show open circuit to ground.
Al.

[kong]

Thanks Al, worked a treat
Just for future reference though, I take it if I got the run and start windings mixed up it wouldn't run at all right? I don't want to have the motor burn out on me after 30 seconds!

[Al_The_Man]

If you have the two windings mixed it will probally start and run but the run winding draws more current and, yes you would burn it out, by monitoring the off-load current would tell you right away.
Al.

[kong]

Damn it, I have installed the motor onto the lathe, but I have very little torque. Most of the time the motor will not even turn, it just hums. Any ideas? I will go and test the capacitor shortly, but I checked the resistance on the windings like you said before, and think I have the start and run windings the right way around. Perhaps this motor was burnt out in the past eh?

[Al_The_Man]

A couple of possibillities, is the centrifugal switch closed initially and when it runs can you hear it open? If the switch is open it will only start/run if you give it a spin. If the above are OK and it does not deliver torque at load, it is possibly burnt out/shorted turn.
But check if you can wether it is a capacitor start/capacitor run i.e. no switch or Capacitor start/no cap run (has switch).
Another scenario is the switch is welded, if this is the case as soon as it get up to around 25% to 50% rpm remove the start winding lead. If it runs OK then the switch needs replacing.
Al.

[kong]

Hi Al, the switch is fine. Under no load, I can hear the switch close up when I switch the motor off. If I test the resistance of it, it is pretty much a closed switch.
How do I tell if it is a cap start/run motor? The label says "capacitor motor".
Oh yeah, even under no load, the motor is running hot.

[Al_The_Man]

Originally Posted by kong How do I tell if it is a cap start/run motor? The label says "capacitor motor". Oh yeah, even under no load, the motor is running hot.

Its a Cap start/no-cap-run if it has a switch.
If it is hot (high current) with no load and you have the two windings correct then there is every possiblilty it is 'cooked'.
Although just because you hear the centrifugal switch, the contacts can still be welded, as you are hearing the mechanical mechanism not the switch itself.
When it is running at speed, there should be no start winding current whatsoever.
Al

[Al_The_Man]

If you find it needs a rewind and can find a friendly local company that will rewind a stripped core, I can tell you how to prepare it and save alot of cash, as the stripping part is usually as time intensive as re-winding, they have to have the motor coil data on file for that particular motor which if it is a common make/model it should be no problem.
Fit new bearings yourself and possibly a new switch.
Al.