3-Phase Motor Conversions: Are They All Hype?

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3-Phase Motor Conversions: Are They All Hype?

This topic has 36 replies, 22 voices, and was last updated 31 July 2018 at 19:56 by Niels Abildgaard.

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30 July 2018 at 20:32 #364743
Neil Lickfold
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@neillickfold44316
Maybe you need to get back to them, so that the person who helped you, finds out that they either messed up, or need more training. Possibly take it further up the chain. The local place here in Hamilton, they will set the drive to suite the motor and the application it is being used for. Really great service too. Companies are only as good as their staff.

Neil
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31 July 2018 at 07:00 #364788
Pete Rimmer
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@peterimmer30576
Posted by Neil Lickfold on 30/07/2018 18:19:44:

After setting the motor to the lower voltage option, get the hand book that came with it, and check the current settings, for your motor. From the motor data plate. The drive will generally go from 20hz to 50hz, but is programmable to 400 hz. Don't go over 70hz on the max limit. Some say don't go over 60z,(USA and Canada power frequency). Like others have said, as the frequency drops,so does the RPM, and so does the total power available. Also there is breaking options, and slow down/ decelleration settings. I think mine is like 0.3seconds or something like that, and have the accelleration at the same rate, on the motor start up and shut down.

I am surprised that if you brought the unit as a complete set up ready to run, that they would have the motor not in the correct configuration. I am assuming that your VFD is the 220V 3phase output one, and Not the 415V output one.

I have a microswitch inline on the S1 control circuit. This micro switch I use is a normal closed one, and is opened/broken circuit when the contact is made. It stops the lathe for when I do forward thread cutting. And allows me to turn the switch to reverse to wind back for another threading pass. Really good for internal threads. I have some pictures in my Album with it.

Neil

What's your reasoning for not exceeding 70hz on the drive Neil? Most lathes have 4-pole motors which will happily run at the speed of a 2-pole.
31 July 2018 at 07:42 #364791
Ray Lyons
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@raylyons29267
Many years ago, when the 1/2 HP motor on my Myford S7 began making noises, I bought a controller from EBay and using a secon hand 3/4 HP 3 phase motor began using a bench setup to test. After some time pouring over the manual and getting nowhere, my son came along to see what was happening. Without looking at the manual he just began tapping the keys on the controller and the motor started. He said that all controllers use the same logic. Did not understand then or now but I have since installed these controllers on the Myford,(with a new 1HP motor) Sealy mill/drill and a shaper. The next project , which has already been bench tested is to fit one with a 2HP motor to my Warco BG600 lathe, although this is a bit more complicated since I would like to retain some of the features of the Warco, such as the leaver start/stop and the safety switches. This is one to ponder over the winter.
31 July 2018 at 09:43 #364802
not done it yet
Participant
@notdoneityet
I don’t know, definitively, what you mean by “50% setting”. If it is at 25Hz, do not heavily load the motor for more than a short time, or you may/will overheat it. The cooling fan is not effective for high loadings at slow speeds – it was chosen to be adequately effective at its normal running speed.

The same for doubling the motor speed – the fan for a 2800rpm duty would be very much smaller than one for half that. It will soak up far more power at those speeds and may not physically be built, or secured, well enough on cheap motors – so beware! I try to not exceed about 80Hz as there may be other parts of the installation which will not cope with excessive speeds. Plain bearings are one example and chucks may be another.

Edited By not done it yet on 31/07/2018 09:45:01
31 July 2018 at 10:06 #364806
john fletcher 1
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@johnfletcher1
When I fitted my pre-owned inverter ( originally supplied by RS, no push buttons just DIP switches for programming)several years ago I was aware of the possible cooling problems at slow speed, such as when screw cutting. I monitored the motor temperature and it didn't seem to get any warmer. Having taken lots of small motors to pieces I have never noticed any difference on the size of the cooling fan 2 or 4 pole, I think the manufactures make one size of rotor for both, same with the centrifugal switch a cheap way out, the cost of small motors couldn't justify changes. John
31 July 2018 at 12:23 #364841
Neil Lickfold
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@neillickfold44316
What's your reasoning for not exceeding 70hz on the drive Neil? Most lathes have 4-pole motors which will happily run at the speed of a 2-pole.

I was told that the motors, 2 pole or 4 pole can safely go to 40% over their rated max rpm.

Neil
31 July 2018 at 13:33 #364850
Nick Taylor 2
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@nicktaylor2
Posted by Neil Lickfold on 31/07/2018 12:23:52:

What's your reasoning for not exceeding 70hz on the drive Neil? Most lathes have 4-pole motors which will happily run at the speed of a 2-pole.

I was told that the motors, 2 pole or 4 pole can safely go to 40% over their rated max rpm.

Neil

You will probably find that a lot of these companies state the continuous output rating. For example on inverterdrive.com they state a continuous and a part time max speed. For the TEC motors the part time rating is usually 200%, or 100Hz for the 50Hz motors with the continuous rating being the much touted 70Hz.
31 July 2018 at 14:15 #364855
John Haine
Participant
@johnhaine32865
2 and 4 pole motors are most likely to differ only in the stator windings, using the same rotors and bearings. 40% overspeed on a 2 pole motor is about 4000 rpm, so you should be able to take a 4 pole motor up to the same speed and get the same loading on the rotor.
31 July 2018 at 17:04 #364871
DrDave
Participant
@drdave
What a difference a day makes. I have been using my lathe much of today and it is a machine transformed. No more worrying about stalling the motor whilst turning.

Thanks again everyone.

Oh, I have left the maximum frequency at 50 Hz. I might consider 60 Hz later; the headstock gives speeds for both frequencies, so I should not be overspeeding anything. Still need to check the chucks, first, though.
31 July 2018 at 19:34 #364893
Jon
Participant
@jon
Think i know the seller Dave up NW, went through same process after specifically asking such matters. To be greeted with an email stating they dont, consult manufacturers of motor and Inverter but sent a circuit diagram for the pendant controller.
Very dear considering have to work it all out and £19 delivery charge that took 3 days for a pendant is unreal. Same Mitsubishi bought else where around £60 cheaper and arrived 2 days quicker, same with a better motor Brook Crompton motor bought from a dealer in Scotland, next day and at least £42 cheaper.

Still to faff around wiring it in since last October i am just using the motor bought, dare say i wont use the Mitsubishi and pendant it serves no added benefit but hassle and space needed to do so.
31 July 2018 at 19:45 #364896
Andrew Tinsley
Participant
@andrewtinsley63637
I really think that you should name the suppliers. Seems they are in the business of extracting the maximum cash for the minimum of work.

Andrew.
31 July 2018 at 19:56 #364897
Niels Abildgaard
Participant
@nielsabildgaard33719
Posted by DrDave on 31/07/2018 17:04:32:

Oh, I have left the maximum frequency at 50 Hz. I might consider 60 Hz later; the headstock gives speeds for both frequencies, so I should not be overspeeding anything. Still need to check the chucks, first, though.

Teco makes motors and state that 2 pole motors from frame size 100 and down can run 5200 rpm or ca 85 Hz all day long and four poles 3600 rpm or ca 120 Hz
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