Post by thread:Re: [EE] Induction motor ID

part 1 912 bytes content-type:text/plain; charset="iso-8859-1" (decoded quoted-printable) Dear collective brain, trying to determine the type of motor I'm wanting to use a speed controller with The label says Class E Induction Motor, 120W, 50Hz, 1400rpm Unfortunately not branded so I can't get more information. At this stage I'm reluctant to strip the whole machine down so I can take the motor completely apart >From what I can see - P and N go into the motor case via the power switch. A 4uF 250VAC capacitor is on the outside, with two wires going from it into the motor. With the cap disconnected I read 144 ohms across those two wires, and 45 ohms across P and N Comparing with the diagrams, the most likely configuration looks like (to me) a Permanent Split Capacitor, with a 45 ohm Run winding and 99 ohm Start winding Sound reasonable ? BTW, the ticks and crosses indicate which motors are suitable for this speed controller TIA Joe part 2 13267 bytes content-type:image/gif; name="induction_motors.gif" (decode) part 3 181 bytes content-type:text/plain; name="ATT00001.txt" (decoded base64) -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at mailman.mit.edu/mailman/listinfo/piclist

See "AC Induction Motor Fundamentals" (00887a.pdf) by Microchip. It's a good induction motor primer. Pages 11 and 12 describe the various motor classes. On 5/2/2012 6:54 PM, IVP wrote: {Quote hidden}> Dear collective brain, > > trying to determine the type of motor I'm wanting to use a speed > controller with > > The label says Class E Induction Motor, 120W, 50Hz, 1400rpm > > Unfortunately not branded so I can't get more information. At this > stage I'm reluctant to strip the whole machine down so I can take > the motor completely apart > >> From what I can see - P and N go into the motor case via the power > switch. A 4uF 250VAC capacitor is on the outside, with two wires > going from it into the motor. With the cap disconnected I read 144 > ohms across those two wires, and 45 ohms across P and N > > Comparing with the diagrams, the most likely configuration looks > like (to me) a Permanent Split Capacitor, with a 45 ohm Run winding > and 99 ohm Start winding > > Sound reasonable ? BTW, the ticks and crosses indicate which motors > are suitable for this speed controller > > TIA > > Joe > >

Listen for a 'click' when the motor first starts, or spins down. That would be a motor with a centrifugal switch, and you'll hear the weights snapping back and forth., which won't work with the controller. Given the power rating it likely does NOT have a centrifugal switch, so you should be OK with your controller. If you can monitor the motor current with a scope, you will see an abrupt, step change in current if is has a switch, and rounded pulse if it just uses a static capacitor.

On Wed, May 2, 2012 at 9:10 PM, Robert Rolf <spam_OUTRobert.RolfTakeThisOuTualberta.ca> wrote: > Listen for a 'click' when the motor first starts, or spins down. That > would be a motor > with a centrifugal switch, and you'll hear the weights snapping back and > forth., > which won't work with the controller. > Given the power rating it likely does NOT have a centrifugal switch, so > you should > be OK with your controller. > If you can monitor the motor current with a scope, you will see an abrupt, > step change in > current if is has a switch, and rounded pulse if it just uses a static > capacitor. > > R > > You can also look for AC voltage on the cap when the motor is running. If the capacitor is being switched out, it won't be there during 'run'. Given the value of the cap you have, it is likely a 'run cap' since 'start' caps tend to be larger

> Listen for a 'click' when the motor first starts, or spins down. That > would be a motor with a centrifugal switch I've a couple of larger motors which have quite an audible click, and this small one doesn't, so I'm reasonably confident it's not switched - Marcel - Thanks for the pdf. I've had a read, informativ