Split phase motor

[PERSPOLIS]

HI everyone
I working on a motor 110 v .The motor starting system consist of overload, centrifugal switch, and 3 wires (black, blue and yellow) coming out of the stator winding.I have not the schematic
diagram but I am wondering if there should be 4 colored wires out of stator housing rather than three wires or internally connected (I mean common wire) and if so then how can I trace the common wire.
Thanks Guys

 

[Gil47]

If you have 3 wires then you should be able to do resistance tests between the leads
Identify the two wires with the highest resistance across them and the remaining wire will be the common .
You will probably have two resistance values that are close in value the other will be and addition of those two windings.

 

[leitmotif]

See if this helps
http://www.patchn.com/index.php?option=com_content&task=view&id=45&Itemid=74

Dan Bentler

 

[PERSPOLIS]

If you have 3 wires then you should be able to do resistance tests between the leads
Identify the two wires with the highest resistance across them and the remaining wire will be the common .
You will probably have two resistance values that are close in value the other will be and addition of those two windings.

Thanks for the reply but what about colored wires

 

[Gil47]

For all I know the man in the factory chose three different colours that he liked and attached them to the ends of the windings .
If you follow what I said about resistance test on the 3 wires you will find out which one is the common.

You tell us what colours give you what resistance then maybe we can help you.

 

[troylibby]

you say split phase motor? it is a 110v single phase motor? I would believe it to be a 2 speed 110vac shaded pole motor. what is the make does it not have a namplte on the frame? is the centrifugal switch internal to the motor most are?

 

[leitmotif]

Read the motor nameplate make model serial no and all that other stuff. Look it up on the Web or call the factory.

Relying on wire colors is not a good bet - there seems to be no standard.

Dan Bentler

 

[PERSPOLIS]

The name plate is almost erased but it is 110 v and single speed. As I said it has one centrifugal switch, overload, without capacitor.

 

[PERSPOLIS]

HI AGAIN
as I mentioned on my post there are three wires coming out of stator windings which are black blue and yellow. I did measure ohmic values as follows:
black to yellow =5.3 ohms
black to blue =4.7 ohms
blue to yellow =1.1 ohms
I am certain that blue and yellow is the run windings and black connected to centrifugal switch but motor just tries to turn but stops with hum noise. There is no short at all but what is the problem here. Thanks a lot

 

[todster]

I'd be willing to bet you're correct on what you think the wiring is supposed to be. You said no cap so it must be a 1/2 or 1/4 hp motor. The start will usually have the higher resistance. Are the contacts on the centrifugal switch for the start circuit dirty or burnt? Try cleaning them up. Check the spring tension. You should be able to buy a repair kit for the switch if it's needed. I bought a brand new 5hp compressor motor, worked great except on occaision it would sit there and hum. Wasted time blaming the compressor. Turns out it had a burr on the switch sleeve and would hang once in awhile, making me think the unloader wasn't working. If you use a spray cleaner after you file the contacts, do your shorts a favor and air it out good first. That little poof and ball of fire out the end when the start winding kicks out is a bit unexpected. Not that I know anything about that but......

 

[PERSPOLIS]

Thanks for the replies, I will let you know the results.