Ancient single phase electric motor - reversing the rotation

[AndrewB]

Morning Gents,
I hope that you can help me with this problem. I am not an electrician - I just know enough to be dangerous.

I recently bought this beautiful beast :



It's a Denford tools Viceroy pillar drill from the 60s or maybe even the 50s. Nice and cheap with one catch - it had a non original 3 phase motor with some strange rating on the data plate which baffled both the bloke I bought it from and my friendly electrical expert. Therefore - much as I would have liked speed control - I went the easy route and bought an ancient AEI single phase motor with the necessary – and hard to find - 5/16” shaft for a tenner.




Having played with the internal shimming, fabbed up a new bracket and swapped the contactor I now have a lovely working quality pillar drill for under £80. I like a bargain.

However - it goes the wrong bloody way round and as I want to make holes not fill them I'm a bit puzzled.
I swapped the L and N on the motor - no difference. A quick google tells me it must be a split phase motor - never heard of them.

So chaps - what do I (can I ?) do ?

An idler pulley is an option but a lot of faff. I can't afford any more major expense on another motor or going the 3 phase route - I want to work with what I've got.

If I open up the motor (been in there already for a once over and to free it off) can I swap the orientation of the central outer section (don't know the correct term) whilst leaving the armature and end caps in the same relative positions. I'm guessing there will be a couple of wires to swap as well although as the photo shows - the 2 supply cables are connected to the centre 'barrel' NOT the bottom end cap.

Logically - when these motors were built - they must have been designed so that they could be provided with either rotation so as to suit different applications ?

I'm sure it's not quite that simple but any advice would be appreciated.

Cheers

Andrew

 

[Marvo]

Does the motor have a capacitor attached?

 

[AndrewB]

Nope - no capacitors externally and didn't notice any inside but then I wasn't particularly looking.

As I understand it - which isn't a lot - a split phase doesn't have capacitors.

 

[sean_ork]

Put the original 3ph motor back on and find yourself a cheap inverter

Plenty on eBay, just make sure its big enough, for that size drill you don't need a monster - I've bought a few previously for less than £30 delivered - no messing swapping belts to change speed.


Vacon 10 - 0.55kW (0.75HP) 230V 1ph to 3ph - AC Inverter Drive Speed Controller | eBay


3 phase converter | eBay


240V Single to 3 Phase Converter | eBay

 

[AndrewB]

This is the non original 3 phase motor that was on it - which the previous owner hadn't manged to understand or get working.



He and others told me that fitting an inverter is not an option with this motor. Can't remember if it was the STAR configuration or the 400/440 in the voltage box (i.e. NO mention of 240) that was thought to be the problem.

 

[malcolmsanford]

You should be able to use inverter start on a Star motor to be honest. The inverter supercedes the need for star/delta start on a 3 phase motor

I'm no motor expert by any means and some of the more knowledgable lads may shoot me down, but what Sean posted would seem to work for me, and well what have you to loose?

Edited because I put delta instead of star

 

[sean_ork]

I'm no expert either but isnt star wired the same as Y - most of my old 3ph machinery is either star or Y plated, and I've connected them up the same.

Can you post a picture of the windings terminations ?

 

[AndrewB]

I thought 'Star' was 'Y' - the only alternative being Delta ?

I'll do some digging tonight and see how it comes apart.

 

[Bobster]

That old 3 phase motor doesn't have an insulation class high enough to be run on a VSD.

That being said, it could run fine for years on a vsd...

400 volt output in star will likely mean it needs 230V delta. Leave it wired in star, the vsd will come as default with a 400v output.

 

[Barry White]

The motor is Flp (flameproof) and in the terminal box there is no access to the start winding.
To reverse this motor the start windings need to be swapped. the start winding is usually thinner and is connected to a simple centrifugal switch. The motor will have to be stripped down to access the windings.



In the above drawing i have not connected the start windings to anything just tried to explain where they need to go

Found this on youtube it shows inside the motor and the centrifugal switch can be seen

https://www.youtube.com/watch?v=Mnz82o1XYeg

 

[Barry White]

Not seen a vsd that is 230v single phase input and is 400v 3 phase output There may be one but its not common and suspect a heavty price tag.
most vsds output the voltage they are inputted with they just change the phase and frequency

 

[Bobster]

Not seen a vsd that is 230v single phase input and is 400v 3 phase output There may be one but its not common and suspect a heavty price tag.
most vsds output the voltage they are inputted with they just change the phase and frequency

VSDs with a 230V input are common as muck, and aren't a lot more money.

Just had a look, entry level 230V VSD's are cheaper.

http://www.parmley-graham.co.uk/var...e-phase/sinamics-v20-entry/6sl3210-5bb15-5av0

Obviously Siemens is one of the top end brands so cheaper will be available.

 

[Barry White]

VSDs with a 230V input are common as muck, and aren't a lot more money.

Just had a look, entry level 230V VSD's are cheaper.

6SL32105BB155AV0 / 6SL3210-5BB15-5AV0 - Siemens V20 - 0.55 kW / 3.2 A (FSA without fan), Filtered

Obviously Siemens is one of the top end brands so cheaper will be available.

All correct Rob But the output on a 230v VSD is ???? and the motor is wired in star at 400v it will run but at a fraction of its power because of the reduced voltage
please check the output voltage of the VSDs 230 in =230 out 400v in =400v out

Cheers Myke

 

[Marvo]

I'm with Rob, high dv/dt issues associated with VFD's will destroy the windings of an old motor, you can add filters but rather don't go there, it can get quite involved.

If it is a split phase motor there's two ways to reverse the direction, either you can reverse the two wires of the start winding or you can reverse the run winding. Actually there's three ways, you can also occasionally unbolt the two end caps of the motor and reverse the entire stator but this is not advisable unless you know the motor was specifically designed to do this.

To reverse the start winding you'll probably have to remove the entire termination block with the connection posts on it and look underneath it. You should see the four winding wire connections under there. To identify the start winding you'll need to resistance test both windings and the start will be the one with higher resistance.

 

[Bobster]

All correct Rob But the output on a 230v VSD is ???? and the motor is wired in star at 400v it will run but at a fraction of its power because of the reduced voltage
please check the output voltage of the VSDs 230 in =230 out 400v in =400v out

Cheers Myke

Output can be set to 400v with a 230v input

 

[Barry White]

Can you link me please Rob to this Vsd if so it could be usefull

 

[Besoeker]

Output can be set to 400v with a 230v input

To get 400V output you would need a DC link voltage of 540V (or greater). With only 230Vac in you can't get that. Unless you add a transformer.

 

[Bobster]

To get 400V output you would need a DC link voltage of 540V (or greater). With only 230Vac in you can't get that. Unless you add a transformer.

Correct, I've never stripped one of the VSD's down. But I'd imagine they have one built in.

 

[AndrewB]

Many thanks to everyone for their input (not that I understood all of it) especially Mykey for giving me exactly the info I was after. I'm sure the drawing will become clear to me once I'm in there. Thanks also to Marvo for suggesting that turning the stator over is a possibilty - I'd rather do this than fiddle about with old soldered joints and age hardened wire and connections.
If you're all still interested I'll post some more pics of the guts when they're exposed. After that I'll decide which route to follow.
Thanks again.

 

[AndrewB]

Hmmmm. Not sure what I was expecting but probably not this.



Firstly 2 off 20 microFarad capacitors sitting loosely in holes in the stator casting (which definitely isn't reversible).
A spring further in suggesting a centrifugal switch - yes ?
The wiring all looks to be in 'good' undamaged condition although perhaps showing its age a bit.
All the connections and screws have corrosion on them and the nut on the A2 connection was not clamping the terminal at all - almost a 2mm gap between the 2 nuts. It still appeared to run smoothly and quietly.

I'm trying to relate the above pic to Mykey's diagram but the only markings on the brown board are A1, A2, A3 and A4 so I'm still a bit stumped.