changing a 3 phase wall saw to single phase

[guineafowl21]

I’m actually looking at a Wadkin RBD planer 3ph/400V, but no-one can tell me if it’s dual voltage or not. I have 3ph to the workshop, but only in the form of a large DB which requires MCCBs (not MCBs) which are expensive, and a sub-board from that.

So I’m in the same position as the OP. It’s harder than I thought to find a step-up VFD (1ph 230V -> 3ph 400V).

Another option is to run the machine with an off-the-shelf VFD, and set it to put out 3ph/230V at 29Hz. The motor will run at 2/3 speed. A pulley change might then be done.

Yet another option is to dig in to the windings and bring out the star point, to enable delta conversion. As I say above, I did this, but I had not much to lose as the machine was cheap. A good motor shop would be a goldmine.

There are things such as rotary phase converters, but don’t know much about them, and odd capacitor solutions that may not be very good.

Final option: install single phase motor.

Next stage for the OP might be a photo of the connection box in the motor. 6 terminals good. 3 bad.

 

[Myfordman]

Agreed all points.
Voltage converting inverters can be bought from drives direct but are expensive reflecting their ease of use with fixed star motors.

 

[guineafowl21]

Thanks - I hadn’t seen the drives direct website. Wow, those step-up VFDs are expensive.

Another option, a bit round-the-houses: Swap the current motor for a modern 3ph one, and run that on a VFD. It would be smaller, smoother, cheaper (and just better) than a 1ph one, and you would have soft start, speed control, etc., and retain the ability to run on either supply. You could then sell the original one.

 

[Myfordman]

For something like a wall saw, the motor body might well be a custom one with a speed up gear drive to make a more compact head.
I also note that the motor plate data is not as comprehensive as you would find on a stock motor and bears the name of the saw manufacturer rather than a known motor maker.

 

[guineafowl21]

I’d almost forgotten what was being powered!

In that case, the best course might be to price up a 3ph supply, be shocked at the cost, and in the meantime find a motor shop to attempt (or attempt yourself) a star point extraction. As long as you do no harm, if you fail, then you can run it 2/3 speed with a VFD. If you don’t want that, then a step-up VFD is your next best thing.

 

[Spectric]

Hi there

Holtzer saws may come in very large sizes but for most people running woodworking machinery from a domestic single phase supply 16 amps is adequate. The one thing a VSD cannot do is increase the power available, volts x current OUT cannot be greater than volts x current IN. 3 phase motors used to be started in STAR configuration, effectively applying 400 volts across two windings and a 1.73 reduction in startup current, once running it was switched over to DELTA configuration and full line voltage applied across each winding, line current increases by 1.73 and full torque is provided. The only way to run these from a single phase supply was to apply 230 volts across each winding in star mode with a phase angle of 120° using the star point as a common neutral. Dual voltage motors are rated less than 4Kw and run either Star(400vac) or Delta(230vac) . As said you need to provide the motor details in order for anyone to provide an answer.

 

[desmo11225]

Thank you every one for all those suggestions and ideas ,so much to chose from , I think the best idea is , to change the old German motor to a modern motor with a suitable VFD/Inverta that would give us a fresh start as trying to match the old technology to the new is not going to be straight forward at all , and even may be impossible , what are your thoughts on that idea, thank you all once again and for being so patient. desmo11225

 

[guineafowl21]

As above, fitting a motor might be difficult unless it’s simply mounted with pulleys. Some pics needed!

Before all that, can you open the junction box on the motor and take a pic/describe?

 

[Ttrees]

Do we get to see the terminals what's under the shroud?

If you cannot figure out how to shrink pictures and you have a windows computer, freely download microsoft sharepoint designer ...the 2010 version only, as it has the microsoft picture manager program to shrink a picture very simply.

Back on topic
If it is a star wound only motor, then I thought it was only about 50% more expensive for those VFD's,
from the Far East but have yet to see any actually using one for a fixed star wound 380v motor only.
Did you read Bob Minchin's (Myfordman's) very useful PDF?, essential reading!
He has this on a google document if you look around for it, or his woodhaven2 forum if you can't find it.

Tom

 

[Spectric]

If you change the motor then just use a single phase motor and no volt release circuit to turn on/off, motors are either foot or flange/nose mounted and hopefully your saw will be belt driven which makes things easier. Remember to check if you want a 2 pole (3000rpm) or 4 pole (1500rpm) motor and maybe the existing pulley will fit the new motor, worst case you may need a new taperlock. Being a German machine it should be well engineered and conform to engineering standards unlike a lot of imported asian stuff so parts required should be available.

 

[desmo11225]

Thank you all once again, I'm going to have to wait now for the saw to be delivered before I can send any info, it should be here before the month is out .
So plenty of time to get all the info we can get ,there's a lot to think about ????? But we would like to get it right first time ,fingers crossed , thank's again every one, I had hoped to join the forum but no luck just yet . All the best desmo11225.

 

[Myfordman]

First thing to photo is under the cover of the motor where the power goes in.
If you are still having photo upload problems, then email it to me as before and I'll do it for you.
[email protected]

 

[desmo11225]

Thank you Myfordman I'm pretty sure we'll be asking for your help again , in the meantime is there a manual I can get ???? , there's a lot of work to do on the frame , I've searched the internet but no luck so far , also a good place for spares , Thank you all once again . desmo11225

 

[Myfordman]

UK service contact should be able to fix you up with a manual in exchange for a model and serial number
Shaun Crump
Service Manager
5 Blacklands Way
Abingdon Business Park
Abingdon
OX14 1DY
United Kingdom

Phone: +44 1235 557619
[email protected]

 

[desmo11225]

Hello, myfordman , sorry for such a long delay everyone but we do have the saw in our possession now and I will persevere with getting this sorted out . The saw is a Holzher type 1205 machine number 1301 - 1980 , so it's pretty old , we have started to strip it down but can'nt see how to take the fan off , and ,if this is necessary ,
Re. Our work shop myfordman there is definitly no 3 phase electricity installed , it is a very old Coal Yard in the middle of Luton , our storage area was the stables for the horses used , it is now a very large workshop . Thank you all once again and let me know if there is any more info you need to help us desmo11225

 

[guineafowl21]

Hello, myfordman , sorry for such a long delay everyone but we do have the saw in our possession now and I will persevere with getting this sorted out . The saw is a Holzher type 1205 machine number 1301 - 1980 , so it's pretty old , we have started to strip it down but can'nt see how to take the fan off , and ,if this is necessary ,
Re. Our work shop myfordman there is definitly no 3 phase electricity installed , it is a very old Coal Yard in the middle of Luton , our storage area was the stables for the horses used , it is now a very large workshop . Thank you all once again and let me know if there is any more info you need to help us desmo11225

Give us some pics of the motor as you strip it down - where the existing connections dive into the windings you (or we) might find the star point that will enable you to run this on a normal inverter drive.

 

[Myfordman]

Hello, myfordman , sorry for such a long delay everyone but we do have the saw in our possession now and I will persevere with getting this sorted out . The saw is a Holzher type 1205 machine number 1301 - 1980 , so it's pretty old , we have started to strip it down but can'nt see how to take the fan off , and ,if this is necessary ,
Re. Our work shop myfordman there is definitly no 3 phase electricity installed , it is a very old Coal Yard in the middle of Luton , our storage area was the stables for the horses used , it is now a very large workshop . Thank you all once again and let me know if there is any more info you need to help us desmo11225

Yes please provide the information already asked about the motor terminal block

 

[desmo11225]

Hi. myfordman , I thought I'd e.mailed you about our workshop , It's an old Victorian Coal yard in the middle of Luton , large premises , some of our storage space is in the stables for horses , definitely no 3 phase installed. desmo11225

 

[Myfordman]

Hi. myfordman , I thought I'd e.mailed you about our workshop , It's an old Victorian Coal yard in the middle of Luton , large premises , some of our storage space is in the stables for horses , definitely no 3 phase installed. desmo11225

Yes you have and I understand that but I have asked you for a photo of the terminals ON THE MOTOR itself to see if it can be changed to 240v 3 phase delta.

Several members here are trying to help you and asking for this information and not providing it is making it rather difficult to guide you.

This is the sort of thing that we need to see.

 

[desmo11225]

Hello everyone, sorry this has taken some time - hopefully the following photos will help with identifying what type of 3 phase motor we have / whether it could run on single phase. thanks for your help.