changing a 3 phase wall saw to single phase

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Established Member
22 Feb 2013
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I know this subject has been discussed in the forum before but some time ago, we have now purchased a Holzer Wall/Panel saw which has a 3 phase motor, what is the best way to convert it to single phase , buy a new single phase motor or a converter /VDF or any other method . Thank you all for your help . desmo11225
I'd go for a VFD if you can. Keep the original motor if it is dual voltage (i.e. has 220, 230 or 240V on the motor plate as well as a number in the range of 380 to 415V.
Normally a smaller, lighter motor for any given power. If you change to single phase you may have to drop the power to keep the same size & weight of motor or mess with the counterbalance.
Much better controlled startup current so easier on the electricity supply if that matters.
If the Holzer has an electric brake, that will be redundant and might fetch a bit of money on ebay to help offset the cost.
The wiring and installation are not complicsted, but they aren't as simple as changing a plug. You need a certain amount of knowledge and as the "we have purchased" phrase suggests it's for business, you'll have to install it properly so that controls, e-stops, stopping time, IP rating, etc are all compliant. But then, that also applies if you swap the motor, it will just be simpler.
Hi there

If you are a business don't you have a three phase supply or could it be possible to arrange for one. All office/industrial type buildings are supplied three phase, it may just be that only single phase boards have been fitted so may be worth checking and I would say a 16 amp supply would be all that is needed. If not then a VSD would be the best option but this will only be possible if the motor can be wired in STAR configuration with a connection to the star point, not all motors can which has given me issues in the past. I assume this is not three phase due to load, it's just a trade rated industrial saw. What size motor is it?
Sorry, had to come back on the views in the last post.
Holzer wall saws can run to several kW and a 16A single phase is nowhere near adequate for larger motors so that's not reliable advice.
Common dual voltage motors are wired Star at 380V and need to be changed to DELTA when run at 240V (typical VFD).
I think you will find that larger motors will be 400volt delta wired in order to permit star-delta starting and so will need voltage converting vfds to run on single phase.
I nearly added that to my reply earlier. There are a fair few of us on here who can possibly give motor help but it would be so much easier if a photo of the rating plate from the motor itself NOT the machine accompanied each query.
Spectric":2dsjmjsg said:
VSD would be the best option but this will only be possible if the motor can be wired in STAR configuration with a connection to the star point,

There are all sorts of motors and configurations, I admit, but this is confusing me a bit. A connection to the star point would be a neutral. Unusual for a three-phase motor. Did you mean a common connection of the windings at the star point?

And usually, the motor is wired in star for 400V, and delta for 240V. If it’s delta/400V, then as said above it’s for star/delta starting and not suitable for a single-stage VFD.

Digression over till the OP responds with more info...
Thank you All for your prompt replies, What manufacturer would you recommend and where on our wall saw would it be installed?????the ones I've looked at seem quite bulky , would some one be able to put a video up or show me where I can see one installed , it's getting more doable, with all your help, thank you all . desmo11225
Pay attention to the replies - you were asked for details of the motor rating plate. We can’t help you without knowing what setup you have.
Thank you , guineafowl21 , Yes I did see that and I will try to get that info in the week , I believe you and I have met up before, sorry to muck you about . desmo11225
It’s hard to get the correct tone with simple text. I was trying to say, ‘slow down, you can’t just get a universal magic box. We need to know what the motor is, then choose the solution, then decide how to mount it.’

At the moment, you’re asking what fuel to use in your car; we’re asking what engine it has, then you’re asking how to open the filler cap.

One step at a time, old son. There’s plenty of time. 8)

Invertek do excellent inverters, by the way.
Well!!!!!! I've certainly slowed things down but I do have a photo of the rating plate of the motor, it's very vague though and would need to be enlarged and a good magnifying glass used , what do I do next , do I need to have permission from the moderators to post it to you , please give me instructions , I have'nt posted to your forum before. Regards desmo11225
There is NO post count restriction on attaching images of a reasonable file size, only external URL sources are restricted to reduce Spam image linking.

Guidance on how to Attach images is at the top of every forum section.
I have tried Guidance on how to attach images at the top of every forum section but I cannot find it ,please help . desmo11225
Hello CHJ
I still have failed to post the image of the rating plate on my saw . I am not the best computer user I know , being a bit old now . Would you help me a bit more please. Regards desmo11225
At last I have the photo from Desmo
Smaller Desmo motor plate.jpg

So what we appear to have is a 400-440 3 hp 3 phase motor which unless internallt reveals 6 terminals and can be re-wired to 240v delta is going to be difficult to run from a VFD.
It is possible in expert hands to convert but I don't think this approach is viable for the OP.

My suggestion would be to get a transwave or similar converter if this is to be run on single phase.
Curiously though I got the feeling that 3 phase might be available in the shop but I could be wrong.
Could you reply please Desmo and say if you have 3 phase available at all?


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