Vertical Milling Machine Refurb

[Onoff]

The BiL has this old, 3 phase vertical mill he wants to get going. Plan is to swap the motor over for a single phase one. I think this might be a double star wound motor hence the two speeds? Thinking he'd be better spending his money on a better phase converter?

 

 

 

 

 

@AnonymousBosch, fancy translating this for me please, from inside the terminal box? German kit. Unfortunately the ID plate has come off and is MIA. No idea of the make.

 

 

Cheers

[JFDIY]

Before I got to the end of your second line of your post I was going to say 3ph with inverter VFD, saves swapping belts over for one thing.

 

 

[Jeremy Harris]

In all probability the motor is just a single speed motor that had a star-delta starter, as those motors have six wires coming from them.  They use a DOL starter relay system, with the motor starting in star and then switching to delta as it spins up.

 

As above, just wire it in delta using a VFD, should work OK.

[Onoff]

Looking at the cheapest option!

[Jeremy Harris]

3 minutes ago, Onoff said:

Looking at the cheapest option!

 

Get a second hand rotary converter and fit a star-delta starter to it and see what happens?

[ProDave]

A VFD can take a single phase in and give a variable frequency 3 phase out.

 

I actually use one in a strange fashion for my lathe.  It was a 3 phase VSD I got free from work, but I only use one phase output on a single phase motor on my lathe.

 

 

[Onoff]

I'm going to go and have a look at it and see if there is a DOL starter on it. 

[scottishjohn]

what is he going to use it for ?

very limted compared to  bridgeport seris II which can be bought pretty cheaply 

£400-£1000 and will do anything you could ever want as the head can move in all directions 

Iuse one for head resurfacing as well as many other very complicated things 

you don,t need all the DRO elctronic things working --thats what costs the money on s/h machines

with no powe feeds its really had work to get a good surface finish on things 

 

Edited April 12, 2020 by scottishjohn

[Onoff]

34 minutes ago, scottishjohn said:

what is he going to use it for ?

very limted compared to  bridgeport seris II which can be bought pretty cheaply 

£400-£1000 and will do anything you could ever want as the head can move in all directions 

Iuse one for head resurfacing as well as many other very complicated things 

you don,t need all the DRO elctronic things working --thats what costs the money on s/h machines

with no powe feeds its really had work to get a good surface finish on things 

 

 

"General stuff" I guess 

 

In the 1st picture to the left is a little capstan lathe in similar dog rough condition Also has a surface grinder there not shown.

[ProDave]

What are they doing outside getting more and more rusty?

 

That top rectangle in the wiring diagram can only be a star delta starter.

[Onoff]

38 minutes ago, ProDave said:

What are they doing outside getting more and more rusty?

 

That top rectangle in the wiring diagram can only be a star delta starter.

 

Long story. Basically they were inside a covered barn but with no windows or doors. 

 

That top box is just an isolator. All wired previously in 3-core and earth flat 1.5mm.

 

The next box down is interesting. You can just see the black knob on the handle. 3 wires in, 6 out. The lever is positions are O, I & II. Not belled anything out yet. It was getting dark and I was 2 beers in anyway.

 

Photos to follow. On SWMBOs phone as mine was dead.

[ProDave]

3 minutes ago, Onoff said:

 

Long story. Basically they were inside a covered barn but with no windows or doors. 

 

That top box is just an isolator. All wired previously in 3-core and earth flat 1.5mm.

 

The next box down is interesting. You can just see the black knob on the handle. 3 wires in, 6 out. The lever is positions are O, I & II. Not belled anything out yet. It was getting dark and I was 2 beers in anyway.

 

Photos to follow. On SWMBOs phone as mine was dead.

That's the one I think is the star / delta.

 

It may be they allow it to run in star for the slow speed and switch to delta for the fast speed.  A motor will have less power in star.  The star delta starters I remember the start (star) position was non latching, you had to hold it there while the motor spun up, then you switched to delta where it latched.

[dpmiller]

VFDs are so cheap and handy now. Had to get one in a rush for a farmer customer recently and just ordered a basic ownbrand one off RS.(Potato packing conveyor) Less than a quarter of the size of the original one, and up and running in no time.

[Onoff]

15 minutes ago, dpmiller said:

VFDs are so cheap and handy now. Had to get one in a rush for a farmer customer recently and just ordered a basic ownbrand one off RS.(Potato packing conveyor) Less than a quarter of the size of the original one, and up and running in no time.

 

Something like this maybe?

 

https://uk.banggood.com/Minleaf-AT1-2200X-2_2KW-220V-PWM-Control-Inverter-1Phase-Input-3Phase-Out-Inverter-Variable-Frequency-Inverter-p-1282676.html?

[Onoff]

Some more pictures. HTF has SWMBO got 7372 photos and videos on her phone? 

 

Where the feed comes in / the isolator:

 

 

The O, I, II switch. 3 blacks in, 6 blacks out:

 

 

 

 

Low down on the left, 2nd photo at the start:

 

 

 

[dpmiller]

9 hours ago, Onoff said:

 

Something like this maybe?

 

https://uk.banggood.com/Minleaf-AT1-2200X-2_2KW-220V-PWM-Control-Inverter-1Phase-Input-3Phase-Out-Inverter-Variable-Frequency-Inverter-p-1282676.html?

 

Yep. I was in a rush/ couldn't risk a wait for Direct Chinesium so got the RS Pro equivalent.

 

https://uk.rs-online.com/web/p/inverter-drives/1223411/

[dpmiller]

Thing with the buttons looks like a NVR, is there a contactor hidden somewhere?

[ProDave]

8 hours ago, Onoff said:

Some more pictures. HTF has SWMBO got 7372 photos and videos on her phone? 

 

Where the feed comes in / the isolator:

 

The O, I, II switch. 3 blacks in, 6 blacks out:

 

 

 

 

Low down on the left, 2nd photo at the start:

 

 

That's the star / delta starter.  Push it one way the cams connect the motor in star, push the other way it's delta.  Off is usually in the middle.  some of them don't latch in the star position as it's only meant for starting, but I have a suspicion they are using it here as a crude 2 speed selector so this one may latch in the star position.

[Onoff]

1 hour ago, ProDave said:

That's the star / delta starter.  Push it one way the cams connect the motor in star, push the other way it's delta.  Off is usually in the middle.  some of them don't latch in the star position as it's only meant for starting, but I have a suspicion they are using it here as a crude 2 speed selector so this one may latch in the star position.

 

Ta. I'm reading this might be known as a "Dahlander" motor? Then that if delivers the same torque in both modes?

 

Also then this star delta starter is completely manual in operation?

Edited April 13, 2020 by Onoff

[Jeremy Harris]

18 minutes ago, Onoff said:

 

Ta. I'm reading this might be known as a "Dahlander" motor? Then that if delivers the same torque in both modes?

 

 

There's a fixed ~1.7 ratio between torque and speed between star and delta connections, so without additional windings (to change the value of Kv) there's no easy way to have either the same torque or speed when switching from star to delta.  Motors produce ~1.7 times more torque, and ~1.7 times less rpm, when connected in star than they do when connected in delta.  As there are the standard 6 wires coming out of the motor (three winding starts and three winding ends) it looks to be a pretty standard 3 phase motor, without any additional windings.

[Onoff]

This I think is how the motor is wound:

 

https://www.wikiwand.com/en/Dahlander_pole_changing_motor

[ProDave]

10 minutes ago, Jeremy Harris said:

 

 

There's a fixed ~1.7 ratio between torque and speed between star and delta connections, so without additional windings (to change the value of Kv) there's no easy way to have either the same torque or speed when switching from star to delta.  Motors produce ~1.7 times more torque, and ~1.7 times less rpm, when connected in star than they do when connected in delta.

The question for @Onoff is does the "starter" latch in both positions.  If so I suspect they are using this as a crude 2 speed control.  As long as the lower motor torque is adequate that would work.

 

The star delta starters I used early in my career you pushed the handle down against a spring and held it there (in star) while listening to the motor run up, and when it had reached full speed you then lifted the handle up (where it then latched until you pressed the stop button) on delta.

[ProDave]

4 minutes ago, Onoff said:

This I think is how the motor is wound:

 

https://www.wikiwand.com/en/Dahlander_pole_changing_motor

I doubt it.  Look carefully at the 2 connections, it is not just a case of bringing the mid point of each winding together as a star point, the whole phasing of the windings changes about, so you would need anything up to 12 connections to the motor to achieve that.

[Jeremy Harris]

10 minutes ago, ProDave said:

The question for @Onoff is does the "starter" latch in both positions.  If so I suspect they are using this as a crude 2 speed control.  As long as the lower motor torque is adequate that would work.

 

The star delta starters I used early in my career you pushed the handle down against a spring and held it there (in star) while listening to the motor run up, and when it had reached full speed you then lifted the handle up (where it then latched until you pressed the stop button) on delta.

 

 

My old 3 phase compressor had a similar starter arrangement, but had an automatic star/delta switch.  It ran more slowly in star configuration for a second or two when starting, then speeded up as it switched to delta to run normally.

 

Looking at the switchgear I'd say it was a pretty standard star-delta switch operated by that lever.  Frankly I think I'd just bin all the old switchgear and wire it up to a VFD.  Relatively cheap and makes the machine a heck of a lot more usable.  I never use the gears on my lathe any more, just change the speed with the VFD as it's so much easier.

[ProDave]

1 minute ago, Jeremy Harris said:

 

 

My old 3 phase compressor had a similar starter arrangement, but had an automatic star/delta switch.  It ran more slowly in star configuration for a second or two when starting, then speeded up as it switched to delta to run normally.

 

Looking at the switchgear I'd say it was a pretty standard star-delta switch operated by that lever.  Frankly I think I'd just bin all the old switchgear and wire it up to a VFD.  Relatively cheap and makes the machine a heck of a lot more usable.  I never use the gears on my lathe any more, just change the speed with the VFD as it's so much easier.

I also remember an automated star delta starter I think using 3 or 4 contactors and a timer relay to sequence them.  It can make quite a bang if you get the wrong 2 contactors energised at the same time!!!!

 

Agree I would just wire it in delta to a VSD.  If you don't want to spend much there are some really cheap ones on ebay if you want to take a punt on something arriving from china or HK.