Ancient single phase electric motor - reversing the rotation

[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.

 

[Marvo]

Lol, I though there might be a cap somewhere, you don't often get motors that size that are split phase.

Firstly the two capacitors are wired to the same terminals so they're in parallel which means they're acting as just one big 40uF start cap, not as two individual 20uF caps.

There's almost certainly a centrifugal switch in there somewhere which will have 2 wires coming off it. Can you see where they go?

 

[PEG]

Hi dude,so it looks like a capacitor start motor,your capacitors seem to be paralleled up. Can you confirm a functioning switch? Was an audible "click" heard,on run up or down? It should be noticeable,on one that vintage.

If so,Mykeys drawing should be your way out.

 

[PEG]

Too slow...:dead:

 

[AndrewB]

Right...... I can see the switch - or parts of it - but I don't remember hearing it click when the motor started.
I can't see which wires go to it without taking the other end cap off. That will have to wait till tomorrow although I've just noticed that of the 4 wires which disappear through the hole in the casting at the top of the photo the black goes into the windings. As the red and blue are connected on the board the brown must be one side of the switch and the blue or the red must be on the other. Which means sod all to me but it might help you guys ?

The more I look at those wires the less I like them - that insulation must be 50,60 .....? years old. It's not old enough to be rubber but it doesn't look like healthy plastic. I may replace it all when (if !) I do the swap - if that's possible without interfering with the windings at all.

Still don't understand where A, Z and Z1 are on my board.

 

[Besoeker]

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

Not as a rule on standard offerings.

 

[Barry White]

At a guess its the blue and yellow (did you call it brown) but need more info. remove the other cover please

 

[AndrewB]

Sorry Mykey, now I've just re read your original post and watched the youtube clip I understand your diagram. I'll finish dismantling tomorrow and once I can see the switch and identify the 2 different size windings I think it will all become clear.

One other question - once converted I'll be running it on the 'starter' winding. Presumably this won't be a problem on a pillar drill but would be on something like a lathe where it runs continuously for sustained periods ?

 

[Barry White]

The start winding just starts it running then is switched off by the centrifugal switch if done correctly the motor will run at full power.
If the start winding was not there you could spin the shaft forward and it would run forward or conversly spin in reverse and it will run in reverse. The start winding just starts it spinning.
please post back before altering wiring as the caps if shorted will go off like a shotgun.

 

[telectrix]

the start winding only runs on start up to provide a phase rotation. . then the centrifugal switch kicks it out.

 

[Lucien Nunes]

To clarify, what you need to achieve is to reverse the polarity of one winding relative to the other. It does not matter which one you reverse because their polarity relative to the mains supply is immaterial. All you need to do is identify the two leads belonging to one of the windings and interchange them.

If you can identify four leads from the windings, by disconnecting them and checking for continuity between them you can make them up into pairs. E.g. if you call them 1,2,3 & 4, and you have continuity from 1 to 2 (one winding) and from 3 to 4 (other winding), then reconnect leads 1 & 2 whence they came but interchange 3 with 4. I would expect Red/Black to be the run winding, and Yellow/Blue to be the start winding, with the starting switch internally connected in series with one of those leads. In this case, interchanging blue and yellow will reverse the motor, but you should do the continuity check and try to follow the leads in case my assumption is wrong.

The start winding and run winding retain their original functions, but the phasing of their currents is inverted so as to produce a magnetic field that revolves in the opposite direction. Once up to speed and the centrifugal switch opens, the motor carries on running in whichever direction it is already running.

E2A: Have you looked inside the covers you have removed? There is often a wiring diagram stuck on the inside.