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Gallery, Projects and General => How do I?? => Topic started by: NormanV on January 15, 2017, 11:50:08 AM

Title: Can this motor be used with a speed controller?
Post by: NormanV on January 15, 2017, 11:50:08 AM
I have a 3 phase 2 speed motor that I am considering fitting to my Raglan lathe. Rather than using a stepped pulley would it be possible to use an inverter with a speed controller to give me a useable range of speeds?
Title: Re: Can this motor be used with a speed controller?
Post by: bertie_bassett on January 15, 2017, 01:54:11 PM
2 speed motors are a bit of a bugger to wire up for an inverter but not impossible.  you will however need an inverter that outputs 415V, if you've got 3  phase it shouldn't be an issue.

you basically have to wire the motor up for either high or low speed, then just use the inverter for speed control.

Id go for the higher speed as its the higher power rating.

you wont be able to use the original switch to change speed but could rewire it to give signals to the inverter if you want to retain that function.
Title: Re: Can this motor be used with a speed controller?
Post by: RobWilson on January 15, 2017, 02:38:12 PM
Hi Norman,

    You really should have two VFD's, one for each set of motor windings, as your not supposed to put any switchgear between the VFD and the motor, But saying that if it was me I would put a mechanical changeover switch between the motor and the VFD, and select high or low motor speed before turning the VFD no.


Rob
Title: Re: Can this motor be used with a speed controller?
Post by: mattinker on January 15, 2017, 06:10:28 PM
I haven't actually seen on, but I've read about on line VFDs that can be programmed for two different sets of windings for two speed motors. Worth looking into!

Regards, Matthew
Title: Re: Can this motor be used with a speed controller?
Post by: PK on January 15, 2017, 06:46:58 PM
Can post a pic of the motor terminals. It's possible that the motor (even though it's a two speed motor) can be configured to run from 220-250VAC..  Depends on what's behind that cover plate...

PK
Title: Re: Can this motor be used with a speed controller?
Post by: NormanV on January 16, 2017, 08:21:04 AM
The motor has a built in speed switch with a off position between each speed so I imagine that it would be simple to wire it up to a VFD, as Rob suggested, without any problem.
Title: Re: Can this motor be used with a speed controller?
Post by: Noitoen on January 16, 2017, 08:51:17 AM
A 2 speed motor's winding is a compromise to be able to split the poles in half to achieve the 2 different speeds. Usually the best winding is the low speed one. Connect this winding to the VFD and it will run ok.
Title: Re: Can this motor be used with a speed controller?
Post by: bertie_bassett on January 16, 2017, 01:57:04 PM
I haven't actually seen on, but I've read about on line VFDs that can be programmed for two different sets of windings for two speed motors. Worth looking into!

Regards, Matthew

the ABB inverters can do this but im not sure about the others, it might not be needed though if there isn't much difference between the two set ups.
Title: Re: Can this motor be used with a speed controller?
Post by: John Stevenson on January 16, 2017, 06:09:33 PM
Short answer is no because one set of windings needs 440v, can't be delta'd as it uses two sets on winding in delta for the other  speed.

To use this you need either a Transwave, a rotary converter or one of those shitty inverters that have been bodged to output 440v
Title: Re: Can this motor be used with a speed controller?
Post by: NormanV on January 16, 2017, 07:05:19 PM
Thanks for the advice, it sounds as if it is not worth the trouble. Another motor won't be too expensive.
Title: Re: Can this motor be used with a speed controller?
Post by: JHovel on January 28, 2017, 08:50:15 AM
I think its worth the trouble!
You DO have to have 415V (not440) 3 phase power coming out of the VFD. The options are to buy a VFD from arceurotrade.co.uk if you don't have 415V in your shed. Put a nice label on your switch that says "Do NOT switch while motor is spinning" and put a stop button wired to the stop control terminals of the VFD right NEXT to it - maybe in the same housing - just so you or a visitor don't get tempted.
Sometimes its worth having a two speed motor. This motor may well give you 5600rpm in the high speed range and plenty of torque at 300rpm  in the low speed range. You don't need to rewire anything in the motor. These are 'Dahlander' wound Delta/double-Y motors. And in delta they still need 415V because they connect two coils in series in each of the delta legs (and in parallel in Y, making it 'double-Y).