Hello.

I got this induction motor with cap and centrifugal switch. It has 4 wires. I have looked up in the internet but a lots of schemes has anotheer cap and this motor it hasn´t it.



Te resistance between wires is
yellow - gray 8,1 ohms
green - red 8,1 ohms

Green and a terminal of the capcacitor 0 ohms
green wit the other terminal of the cap 27 ohms

Thank you

Best regards

 

So it appears to be a PSC motor, which means you can use either winding for the run & start, i.e. connect one pair across the AC power, the other place a capacitor in series and also across the ac .
Swap each winding to reverse.
This PC does not have my schematics on it, but I can post later if needed.
But a PSC motor does not have a centrifugle switch?

 

Thanks for your answer.

Yes, it has a centrifugal switch connected wit the capacitor. It is hard to take a picture, but one of the terminal of the capacitor is conected to the switch, and the other one ot the switch goes to the coils.

 

Can you see where the cap is actually connected to in the photo, i.e. it two blue conductors?

 

The 2 blue connector from the capacitor go to inside the motor. One of them goes to the switch and the other one goes to the coils. The other terminal of the switch, which is blue too goes to the coils

 

It is very unusual to rely on one winding in a AC motor application.
Generally there is both windings left in circuit.
Have you tried to run it VERY briefly, see what occurs.

 

Have you tried to run it VERY briefly, see what occurs.

Yesss, that is what I was thinking. but not plugin it direct. Which option is better? Reducind the AC voltage with an autotransformer or use a dimmer?

And how must I connect it? The terminals in pararallel?

yellow - gray 8,1 ohms
green - red 8,1 ohms

So yellow whit green and gray with red?

Thank you

 

If green is going to the capacitor it could not show continuity to red if wired in series with the start switch as it should show open.
I would investigate a little further and draw out the actual schematic first.

 

Thank you soooo much for all your help.

I have dissasemble the motor to open the switch.

This is the schematics



It seems to have 3 coils (Unless one of them is a resistor)

 

Looks as though the 20 ohm is the start winding. Try if very briefly with power applied to GRN + YELL and RED + GRAY , odd there is no capacitor in the run mode.

 

Looks as though the 20 ohm is the start winding. Try if very briefly with power applied to GRN + YELL and RED + GRAY , odd there is no capacitor in the run mode.

You are great!!! It works. Thank for all your help

I tried what you said with an autotransformer at 100V (The motor is rated to 220V). Start running and at very low RPM the centrifugal switch open. When I disconnect it at the end of the video you can heat that switch closing again. And yes I should fix the motor to the table but it was a low voltage and I didn´t expect a great inertia/torque.

But one question, in this configuration, once the switch opens, there are 2 coils of the same resistance (8 ohms) running. Is that normal? Or maybe each one is for one turning direction?

.

 

Yes, as in my post #2, you can often find both windings identical on motors under 0.5HP.
As a rule, a cap is left in circuit in order to obtain a phase shift in that winding.

 

Ahh ok ok. But what is this other coil for? I tried it whit only whit green and red and it guives the same rpm 1490

 

From your DWG it shows three coils, one is the start, in series with the cent. SW, the other two are run windings, which must have some phase shifted offset.

 

ook thank you