Author Topic: Can this motor be used with a speed controller?  (Read 704 times)

Online NormanV

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Can this motor be used with a speed controller?
« 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?

Offline bertie_bassett

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Re: Can this motor be used with a speed controller?
« Reply #1 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.
a competent engineer uses the tools and knowledge available, to get a challenging job done.

 An incompetent "engineer" tells his boss that the existing equipment "can't do the job" and to get another machine

Offline RobWilson

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Re: Can this motor be used with a speed controller?
« Reply #2 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

Offline mattinker

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Re: Can this motor be used with a speed controller?
« Reply #3 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

Offline PK

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Re: Can this motor be used with a speed controller?
« Reply #4 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

Online NormanV

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Re: Can this motor be used with a speed controller?
« Reply #5 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.

Offline Noitoen

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Re: Can this motor be used with a speed controller?
« Reply #6 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.

Offline bertie_bassett

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Re: Can this motor be used with a speed controller?
« Reply #7 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.
a competent engineer uses the tools and knowledge available, to get a challenging job done.

 An incompetent "engineer" tells his boss that the existing equipment "can't do the job" and to get another machine

Offline John Stevenson

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Re: Can this motor be used with a speed controller?
« Reply #8 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
John Stevenson

Online NormanV

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Re: Can this motor be used with a speed controller?
« Reply #9 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.

Offline JHovel

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Re: Can this motor be used with a speed controller?
« Reply #10 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).
Cheers,
Joe