OT: Motor questions

mrtweaver

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I have an off topic motor question. I have a capacitor in start and run motor. Actually i have two and both are behaving rather unique. I have tested the capacitor and motors and they seem to be ok no ground faults or shorts that can be megged out.

the diagram is capacitor then start winding, and then you have the run winding. there is no throw out to disengage the start winding.

the issue is the one motor will run clockwise fine but when you rev the start winding to rev the direction it will run for about 3 seconds then quit.

the issue on the second motor is the opposite, it will run fine counter clock wise but will only run for about 3 sec in the clockwise direction.

this is with no load laying on the test bench. the motors behave the same way when installed in the piece of equipment when attached to their load.

it just seems kind of weird that you are using the same cap and same windings but you can only get the motor to function properly in one direction. Any ideas or thoughts on what could be causing this?
 
Can you post the exact part number of a motor? It sounds like an incorrectly wired capacitor start motor with a centrifugal switch (even though you explicitly say there is none). It's like the switch is being rewired to the 'run' winding instead of the 'start/capacitor' winding. On the bench you should be able to hear the switch clearly. On the shop floor you may need to use the old 'screwdriver stethoscope' trick.
 
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Well it definately does not have a centrifugal switch. This will be a crude drawing but here it is

---------|(------mmmmm--------------------
| start |
| |
| |
-----------mmmmmm------------
run

the part number of the motor is

5KCP61FW1510S it is a GE motor

to reverse direction you simply change the position of the cap and start field. If the cap is first it runs one direction, if the cap is last it runs the opposite direction.

As i said two motors, 1 runs CW but only for about 3 seconds CCW, the other runs CCW but only for about 3 seconds CW.

If you find the spec sheets on the motor you will see it one that is capacitor start and run and it has no centrifugal switch.

Hope this helps put on the thinking caps.
 
If you find the spec sheets on the motor you will see it one that is capacitor start and run and it has no centrifugal switch.

Hope this helps put on the thinking caps.[/quote]

You have answered your own question with the statement. This motor needs 2 capacitors to run correctly. it is a capacitor start-capacitor run motor. see link. I'm not sure what you need to do to "reverse" this type of motor, but I think both coils have to be reversed if memory serves me right. see the link

http://www.leeson.com/TechnicalInformation/sphase.html
 
As maxketcham says you shouldn't just move the capacitor.

Using your sketch. For both directions you put Line to the left of the sketch and Neutral to the right on the Main winding. For one direction you would do the same for the start winding. For the other direction you don't change position of the capacitor you just swap Line and Neutral on the start winding. Of course you Americans have weird electricity so you might have two Lines instead having a Neutral, but the theory is the same.
 
If as I suspect this is a capacitor run motor both windings of the motor will be of similar resistance.

In this link there is a winding fed with a red wire and one with an orange wire if you want to reverse the motor you connect the L wire to the red to get forward and to the orange for reverse

www.google.co.nz/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1366&bih=677&q=capacitor+run+motor+schematic&oq=capacitor+run&gs_l=img.1.4.0l3j0i5j0i24l6.2222.17262.0.24058.13.11.0.2.2.0.264.2809.2-11.11.0....0...1ac.1.27.img..0.13.2820.aR__F3qraQI#facrc=_&imgdii=_&imgrc=iSczfVq2scVQKM%3A%3BxHeP1Dxi33CpsM%3Bhttp%253A%252F%252Fwww.carymart.com%252Fblog%252Fwp-content%252Fuploads%252F2012%252F10%252Fcapacitor-start-motor-run-forward.jpg%3Bhttp%253A%252F%252Fwww.carymart.com%252Fblog%252Fremote-control-single-phase-capacitor-start-motor%252F%3B350%3B230

Edit
Bit of an ugly link but the best I could find to cover my description
 
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Some motors are capacitor start only with a built in centrifugal switch to disconnect the starter winding once the motor is running. When running the starter winding is no longer required. With this type of motor the start winding is usually lighter copper than the main (running) winding presumably to offset the cost of the centrifugal switch installed.

The other type is capacitor start and run where both windings are of comparable current carrying capacity and therefore the start winding does not have to have a centrifugal switch to disconnect after the motor is running. The motor therefore runs continuously with both windings in circuit. This arrangement is probably more reliable because of the lack of a mechanical switch.
To reverse this motor you can reverse the direction of current flow through either the start winding or the main winding whichever is the more convenient.
 
I don't know that I've ever seen a Cap-Run motor. Very interesting. I guess its not popular due to the low starting torque. Too bad. Getting rid of that troublesome centrifugal switch is always good.

Can anyone identify a manufacturer of Cap-Run motors in North America?
 
I don't know that I've ever seen a Cap-Run motor. Very interesting. I guess its not popular due to the low starting torque. Too bad. Getting rid of that troublesome centrifugal switch is always good.

Can anyone identify a manufacturer of Cap-Run motors in North America?

The place I see these motor are in Kitchen bathroom type ventilation fans at less than 1 HP or in industry where a small fan is wanted.

Thats where I would expect you also to find them .

I agree that centrifugal swiches are the pits
 

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