single phase-two speed motor, two capacitors and one relay

kalabdel

Member
Join Date
Feb 2015
Location
Ontario
Posts
1,108
Hello everyone,


I ran into this 230 single phase two speed motor with two capacitors and a relay (see picture) and have a few questions:
The relay is mounted on the motor, in a casing similar to a capacitor's, what is it for?
Is it a potential relay?
Capacitors, both for staring, one for Low speed and one for high speed, or one of them is run capacitor.
Is there a way to get info (literature) on the motor?

Thanks

IMG_20220526_164121028.jpg IMG_20220525_125307529.jpg
 
looks like it's a standard two speed motor with a start and run cap. the X would be where the relay would cut the start cap out once it got up to speed. usually theres a centrifugal switch for this purpose. but some use things like a "Sinpac" switch, which is a solid state relay for dropping single phase capacitors out of circuit once at speed/voltage

difference in this drawing is there will be another run capacitor always in circuit, typically to improve the efficiency of it.

motor.jpg
 
this is a better picture of how its probably set up

just without the high speed winding. to make it high speed, add another point of contact between the windings to reduce the number of poles (or use another winding altogether). and then a contactor to switch between the two.

motor.jpg
 
That's great, than you gentlemen.


I had a quick look at the rear of the motor and there was no centrifugal switch so I figure this is likely to be a potential switch but the data sheet I I found just called a power relay.
So I understand then that the run capacitor connects to the main winding regardless of the number pole pairs connected, same capacitor for both speeds.


Cheers
 

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