Help Wire 3 Phase 2 Speed Motor

[Mark HallParticipant @markhall37441]

Of course if you decide to wire it to low voltage terminal you will have to set the correct voltage in parameters

[Mark Hall]

On Mark Hall Said:  is it possible to use a single phase in & 3 phase 380V out VFD for this?, …

Can you provide a circuit diagram please?  Is it different from Allan’s compromise, in which the 2-speed motor is wired for one speed only and driven by a VFD of appropriate voltage?

Wiring one VFD to a single motor is straightforward.   Using one VFD to power two motors is asking for trouble, and so is switching a VFD’s output.  I tried to explain why it’s unwise to connect a VFD to a Dahlander motor and switch the windings as the machine was originally configured.  No problem when the supply is true 3-phase, but unwise when 3-phase is generated electronically.   Julie found my explanation muddled, and, if I gave the impression speed is related to impedance, she’s right!  Impedance is nothing to do with speed, other than indirectly due to how the motor is wound.  I was trying to explain why ordinary VFDs don’t like load impedances that jump about due to different windings being connected, and especially dislike their outputs being switched. Sorry I failed, and no-one else has tried!

How risky depends on what’s inside the VFD.  So far I’ve not found an inexpensive VFD that supports mixed loads and/or switching.  Those that do are expensive.  Might change because the cost of electronics tends to drop, but so far, best not to risk mixed loads and/or switching. Check the spec if it’s wanted.

Allan’s solution keeps his VFD happy by strapping the Dahlander’s windings permanently into single speed.  Then there’s no need to switch the VFD, and the circuit becomes conventional, hurrah!

Speed is controlled by varying frequency, not voltage, and the VFD voltage is chosen to match the motor.

Apologies if I’ve misunderstood, but, if proposing something new, how would Mark wire Ub, Vb and Wb?

Dave

 

 

[Mark HallParticipant @markhall37441]

Hi

OK so I I decided to test this out today with this 415V 2 speed motor picturediabove. I did a bench test & it worked so i put it on on a lathe to run it through the RPM speed. I first connected the low speed terminals 1U 1V 1W to the VFD & set the voltage to 230V & maximum Amps 4.3A & selected high gear & i got the lathes rated 1500rpm (obviously its geared) the motor is very smooth.
Next test  i swapped the terminals & connected the high speed motor wires  2U 2V 2W to the VFD & set the voltage to 380V & the maximum Amps to 6.1A & got 3000rpm, again very smooth, I then machined SS for 30 minutes & checked the motor & its cold. Athough i connected it separately there are settings in the parameters to programme both & use them using the M.FUNC button on this VFD so it switches between low/high speed setting but that is for another day as it 6pm now & tea time.

Bear in mind I already have a 2.2kw inverter rated dual voltage motor that I used for this lathe & its a great motor but the 415v pictured is running alot smoother so I’m temped to keep it on the lathe now & use the new one for another project. Wish I new this befor I purchased another motor but its always good to have a spare. There has to be a downside somewhere,  maybe decreased torque IDK but it’s working.

[Mark HallParticipant @markhall37441]

Here is the VFDs I been using , they are available in both  240v in 230V 3 phase out & 240V in & 380V 3 phase out & its the latter I used for this test you can set the voltage above 380V in the parameters but i stuck to 380V max. There is also a external display that is available for this model. I’ve never had a issue with them & all three i have come from there & my linear scales & DRO, they are cheap but the important thing is they work as advertised.

There was somone on the hardinge forum that connected & used a VFD on his hardinge 415V precision 2 speed motor using a drum switch to change the speed & adjusted the parameters to run it one way or the other. I have not go that far, I’ve only tested it wired to the VFD one way or the other. These are 2-3HP motors & maybe there are torque losses but I can see or feel them on the lathe, if there is perhaps it would be more noticeable on a lower HP motor. There are torque compensation parameters on the VFD but I have no experience using them. 

[larry phelan 1Participant @larryphelan1]

Having read through all this, I am now considering going back to bed !

I have the Dreaded Head Staggers !

[Mark HallParticipant @markhall37441]

<p style=”text-align: left;”>It’s simply you set the desired voltage/amps & motor KW power in the VFD parameters like any other set up you do on a VFD then wire either winding & it allows you to run your 415v 3 phase motor. I’m not talking about a dual voltage motor 415/230v that you set up in delta to run off a 230v 3 phase, there is also the other option where you wire both high /low terminals to a drum switch so you have high low gear & set the parameters accordingly.</p>

[Mark HallParticipant @markhall37441]

The motor is still running but I read somewhere that I should set the Hz to 29hz

[Wade BeattyParticipant @wadebeatty78296]

I have a Drives Direct 220 single phase X 415 3 phase inverter that I have used for my Boley 6lz, with a Dahlander 2 speed motor. I have never had any issue with this set-up. It came with another machine purchase but was not used as I could use 220 3 phase.

I have 220 3 phase in my workshop and have considered a transformer but the Drives Direct works fine despite all the hate thrown at it.

Wade

[Mark HallParticipant @markhall37441]

Hi Wade

I’ve looked at 415v VFDs, but they are expensive. These are £40 & allow you to run a 415V motor & more importantly a 2 speed 415V motor.

Here is a update from my testing on a 2 speed 415v motor.

I have been testing these particularly CTL100 VFDs  for the last 2 years & and their excellent. Like all VFDs within the parameters, it allows you to set the maximum motor voltage BUT interestingly you can set it beyond the nameplate 380V. Although it’s sold as a 380V VFD, it has 400V on the front of the drive.

Initially I was running/testing this drive on a 415V 2 speed motor on a 3Hp lathe but with only a 230V output VFD connected to the motors low speed windings (even in low speed the motor still requires 415V but a lower current) however for this test i used a 230Voutput VFD & it worked fine, I got full RPM however at top speed 3000rpm I could tell it lost Hp but as its a 3HP motor it wasn’t noticeable in the other speed ranges.

My latest test was to add a single phase in & 380V three phase out VFD to test/run this 415V 2 speed motor, I wired the high speed terminals to the VFD then updated the maximum current in parameters but set the maximum motor voltage set to 380v. It ran great all week with no issues ( the motor did not get hot or stall & no errors from the drive)

next test i set the maximum motor voltage (in parameters) to 415v, it’s been running all day every day in the workshop for a month.

I have 4 of these VFDs now in both 230V output & 380V output & in all of them it allows you to set the maximum motor voltage to 3 decimal places (theoretically 999v) I would not advise it but 10% beyond the drives 380- 400V seem OK.

It also allows you to view what the motor is pulling/amp/hz/rpm

So why does it work? I read online that it will not work, the motors core would get saturated, the motor would pull more current to compensate for the lower 230v & 380V , the motor would get hot & then burnout . None if these things happened, the motor was not even getting hot.

Is it becase they are modern asynchronous motor? Will this work on other motors?

I have tested this on x2 different 415v motors 1 was a standard 415v motor & the other was a 2 speed 415v motor & both exceeded my expectations.

At only £40 each, these little gems seem to shine

 

 

 

 

 

<p style=”text-align: center;”>At only £40 </p>

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