Confused by induction motor. Need help

[denisParticipant @denis]

Thanks in advance. I have tried to search google etc. but the milling machine I bought on Friday is 3phase 440. And I may have jumped the gun. I disconnected all the wires in the control box. Because I’m going to use a vfd. But when I when to change the motor connection over to delta. It’s not the same as all the others motors I have see online. There a big high and low switch where I was expecting to see terminal.
I guess what I’m asking is it just a case of connecting  the appropriate cables to each other. As all the wires are labelled

[Martin CargillParticipant @martincargill50290]

It’s probably a Dhalander connected motor (google it). Difficult to supply with a 220 volt output VFD.

[denisParticipant @denis]

Thanks Martin. Was hoping it would be an easy fix

[denisParticipant @denis]

I wondering what’s the best course of action. I have email newton tesla. To ask if he does a motor for the mill. But the original motor looks like it has a different base plate that acts as the belt tensioner  does any have a link to a manual for the mill  thanks again

[Robert Atkinson 2Participant @robertatkinson2]

You can use a VFD with voltage step up.
Power will be slightly reduced as they don’t quite reach 440 V but not a issue for hobby work.

[MacolmParticipant @macolm]

It appears to be a pole switched two speed motor, hence the switch. Not simple to change star to delta!

[David SeniorParticipant @davidsenior29320]

That mill and 2-speed motor look the same as my Myford VMF (also the Warco A2F). Mine runs using a converter box from Transwave. I have talked to Newton Tesla about fitting it with a vfd or replacing the motor but they aren’t able to help.

If you do find a solution I would be interested to hear. I would like the speed control of a vfd. At the moment it looks like the only solution is to fit a new motor and make a new base plate for it and some kind of spindle adaptor to take the pulley arrangement.

I can probably scan the cross sectional drawing from the manual if that helps.

Dave

[Martin CargillParticipant @martincargill50290]

I did have the same problem with an Arboga drill. I bought the machine thinking that I could swap out the 3ph motor for a single phase one (it was a two speed motor as well). I removed the motor only to find that the shaft was about 12″ long and had a gear cut into the end.

I ended up removing all of the electrics to the original motor. Then I welded (and machined) an extension onto the fan end of the motor. I then clamped a plate onto the side of the 3 phase motor and mounted a 2hp single phase motor onto the plate. Two pulleys and a belt now transfer the drive from one motor to the other.  The pulleys are two step ones so I still have the two speeds that the original motor had (the machine has a 4 speed gearbox, so belt changes are not required very often).

 

Martin

[denisParticipant @denis]

Thanks Dave. Do you have a wiring diagram for this machine or maybe a few photos of the inside of the control box. . I think my best option now is to put the control box back together. And get a converter transwave.

[David SeniorParticipant @davidsenior29320]

This is probably the likeliest wiring diagram from my manual.

Also the section of the head

Hopefully they help.

Dave

[MacolmParticipant @macolm]

Perhaps the professional advise quoted is realistic (to forget it), but it may not be as problematical as that. It appears to be an 8 pole motor, but by making the windings of every second pole able to be reversed, it goes from NSNSNSNSNSNSNSNS to NNSSNNSSNNSSNNSS, effectively four pole. The switched windings are the least of the problem, both ends of each of these are already able be isolated.

So reconfiguring from star to delta only depends on whether the un-switched windings can be readily converted. If so, it should be able to run from a VFD, but with the vital limitation that power must be completely removed before the pole change switch is operated.

Not  a project for the faint hearted, but it might be well worth investigating for someone who values a challenge. In checking things, a suitable low DC voltage applied to the winding(s) can allow a small compass to be used to plot pole position and polarity.

[Gerard O’TooleParticipant @gerardotoole60348]

Denis, have a read of this thread https://www.model-engineer.co.uk/forums/topic/help-wire-3-phase-2-speed-motor/

If you read down through that thread you will see my reply in that thread, I think I dealt with a similar problem on a Deckel FP1.

In summary, the solution advised by the supplier of my VFD was to connect DIRECTLY to high speed connections,(i.e. remove all speed switches etc. ) and adjust the VFD frequency to compensate for the lower voltage output.

There are more details in that other thread.

 

 

[denisParticipant @denis]

I have an update. Progress has been made. My neighbour works in a factory that uses all 3 phase gear. He came and had a look. And he was confident it would work off a vfd. So after reading though this forum and following Gerard O’Tool post. I said I’d try a really cheap vfd. I wire up the vfd temporarily. And bingo the mill is alive. Thanks to you guys. Thanks very much to everyone.
the electrician alsorewire the transformer to run of from 440 to 220v. So the 110v  travel motor/power feed could work. And the light also works.

[denisParticipant @denis]

Forgot to mention for anyone buying a mill. I made a set of caster wheels so when we lifted the mill off the trailer at home I could move it around on my own. I don’t know if I’ll keep the wheels. But it made it very easy to move the mill into the garage as I don’t own a pallet jack. And I’m not sure where the mill is going to live in the garage as there is a lathe coming in a few weeks

[denisParticipant @denis]

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