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BCA jigborer motor

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Michael Gilligan20/12/2020 12:20:45
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Posted by Matt Mackeson on 20/12/2020 11:42:25:

[…]

I took the access plate off and found this handy wiring diagram for the two speed switch. […]

.

Thanks for posting that useful photo, Matt ... I have grabbed a copy for future reference yes

No immediate need, of course.

MichaelG.

John Haine20/12/2020 12:33:40
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Posted by Matt Mackeson on 20/12/2020 11:45:42:

Ah no I think I made an error there. Because the current motor isn't dual voltage I wouldn't have any speed control with one of the 240V to 380V vfd's. Is that correct?

Regards,

Matt

The voltage has little or no influence on the speed of an induction motor, speed is controlled by frequency and number of poles - hence VFD = Variable Frequency Drive. From John's post above it looks like that VFD does convert 220 V single phase to 380V 3 phase, so is a voltage doubling inverter. So that should do the job fine with the current motor. It looks like the motor must switch from 2 pole to 4 pole for speed control. With the VFD you would simply set to the high speed parallel star connection (which presumably needs no change to the wiring) and do all the speed control through the VFD.

Matt Mackeson20/12/2020 15:35:17
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Posted by John Haine on 20/12/2020 12:33:40

The voltage has little or no influence on the speed of an induction motor, speed is controlled by frequency and number of poles - hence VFD = Variable Frequency Drive. From John's post above it looks like that VFD does convert 220 V single phase to 380V 3 phase, so is a voltage doubling inverter. So that should do the job fine with the current motor. It looks like the motor must switch from 2 pole to 4 pole for speed control. With the VFD you would simply set to the high speed parallel star connection (which presumably needs no change to the wiring) and do all the speed control through the VFD.

Thanks John, so would this be suitable? he 0.75w version.

VFD

John Haine20/12/2020 15:48:07
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What power is your motor? But a 0.75 kW VFD should be ok I think.

John Baron20/12/2020 16:28:07
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Posted by Matt Mackeson on 20/12/2020 11:42:25:

Thank you all for the comprehensive replies. I don't think I have ever had such a quick and thorough set of replies to any post on any other forum!

I took the access plate off and found this handy wiring diagram for the two speed switch. If I understand this correctly the motor uses both star and delta for the two speeeds?

 

So it seems I have three options:

  • a new dual voltage 3ph with a VFD and adapter plate
  • a rotary phase converter
  • Look further into the VFD's posted by John. From what I understand this would give me a single speed on the current motor but then give me speed control through the vfd?

I am learning a lot about electric motors through all this so thank you all again for the help!

 

Hello Matt,

Unless I've misunderstood you, the motor would normally only be supplied from a single 380/440 three phase supply. The VFD that I pointed to, will behave in exactly the same way as any other VFD ! So yes you will have the ability to control the speed as you wish.

Only one caveat do not change the motor speed whilst under power. The VFD has to be switched off before changing speed by using the machines own switch. You will damage the VFD if you forget.

That motor will not run at full power on 230 volts even via a 230 volt single phase input VFD with 230 volts three phase output. You will still get the two speeds but only half or less of the HP.

HTH.

Edited to correct wording !

Re edited to add these VFD's are so cheap that the cost between 1 and 2 HP is very little.

Edited By John Baron on 20/12/2020 16:29:26

Edited By John Baron on 20/12/2020 16:32:23

Matt Mackeson20/12/2020 17:02:31
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Posted by John Haine on 20/12/2020 15:48:07:

What power is your motor? But a 0.75 kW VFD should be ok I think.

The motor is 0.5hp, so 0.37kw

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