Running 380V 3-phase motor on 230V 1-phase

[Robert Atkinson 2Participant @robertatkinson2]

Well I’m not going to respond to any more of Bob’s comments.

Robert

[Andrew SkinnerParticipant @andrewskinner94774]

Has anyone got a comment on my calculations, 26th June 13:11, about halfway down page 2?

They seem to indicate the motor requires 220V line voltage 3ph, not 400V. I’d like to know either way, and I’d say the OP would, too.

[Robert Atkinson 2Participant @robertatkinson2]

We do seem to have been a bit diverted from the original question…
The biggest issue is that the photo of a motor dataplate in the first post,  https://www.model-engineer.co.uk/forums/topic/running-380v-3-phase-motor-on-230v-1-phase/#post-851454
Is NOT off the motor in jimalm’s lathe. So we are all just guessing until we have sight of the ACTUAL motor dataplate.

I have spent some time looking at these 3 phase, 3 speed motors generally. They appear to have 3 sets of windings. Two are a Series Delta switchable to Parallel Star like a Dahlander two speed. The third set are wired Star. But I can’t figure out exactly / definitively how they are connected. I’ve found different motor diagrams and lathe switching diagrams but all of them are either lacking information or have inconsistencies For example a unlabelled connection or mismatched terminal designations.

Robert.

[Andrew SkinnerParticipant @andrewskinner94774]

The way I read the first post, the photo IS of the OP’s motor, but he’s found a photo (not shown) of a similar motor that states 380V.

[Robert Atkinson 2Participant @robertatkinson2]

My bad.

The motor does look to be very inefficient at any voltage or speed.
I’d be looking at a delta connected modern 4 pole motor a with a VFD to attain the  speed variation. If the user is more likely to need most power at lower speeds (cutting big bits of tough material) then a 6 pole would be better. You still get the higher speeds but torque would be reduces but OK for small parts or softer materials where yu want high speeds and sharp cutters.

Robert.

[Robert Atkinson 2Participant @robertatkinson2]

error

 

[Bob Worsley]

On Bob Worsley Said:

….

Oh, and you both are still wrong, a capacitor converter is not limited to 50% power, whatever you say.

Is no one else reading this interested enough to ask questions?

 

Did anyone say it was? I’m just keeping my head down, avoiding the brickbats.

[Bob WorsleyParticipant @bobworsley31976]

I quite agree. Anyone with a similar problem will get no help from this thread, which isn’t, as far as I am aware, the idea of the forum, spreading knowledge etc etc?

 

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

If the Steinmetz connection was an effective method of running electric motors it would be used in industry. It isn’t used in industry as part of the standard design of equipment.  You will always get the odd outlier example but it is not common practice. Show me one piece of commercial equipment that is DESIGNED to run on single phase and uses a 3 phase motor with a Steinmetz connection.

Robert.

 

I’ve already given one example of that. It’s true that I was surprised to find it but the fact remains nevertheless. This was not installed at some tin-pot establishment either it was at a very swanky building in Canary Wharf.

[Andrew TinsleyParticipant @andrewtinsley63637]

Yes Duncan,

Robert Atkinson definitely stated that Steinmetz only provided 50% of the possible motor power. I then stated that this was incorrect, as most analysis of Steinmetz came up with a figure of 80%. I never got a reply, as Robert appears to ignore such corrections that show Steinmetz in a better light.

I find this business very frustrating, Robert obviously dislikes the Steinmetz connection and provides lots of theoretical arguments against it. This from someone who by his own admission has NEVER run a Steinmetz circuit to power real workshop machinery.

I have done so for years and quite a few other people on the forum have done so as well, with quite satisfactory results in practice. I will leave this subject alone from now on, as it gets us precisely nowhere.

Andrew.

[duncan webster 1Participant @duncanwebster1]

Well you’ll have to tell us in which post Robert stated 50%, I’ve just had a quick scan and couldn’t find it. What he did say was that Steinmetz isn’t as good as real 3 phase or a VFD

 

[Pete Rimmer]

On Pete Rimmer Said:

On Robert Atkinson 2 Said:

If the Steinmetz connection was an effective method of running electric motors it would be used in industry. It isn’t used in industry as part of the standard design of equipment.  You will always get the odd outlier example but it is not common practice. Show me one piece of commercial equipment that is DESIGNED to run on single phase and uses a 3 phase motor with a Steinmetz connection.

Robert.

 

I’ve already given one example of that. It’s true that I was surprised to find it but the fact remains nevertheless. This was not installed at some tin-pot establishment either it was at a very swanky building in Canary Wharf.

No, you gave me an unsupported anecdote. How do you know it was designed to run on single phase as opposed to being designed for 3 phase and modified for that installation?
Do you have any evidence? Photos of the equipment rating label and motor rating label would do. Make and model of the equipment?

Even domestic electric gate openers use VFDs these days. It makes complying with safety regulations on closing force etc a lot easier.
And don’t forget that 3 phase motors over 750 W now have to meet minimum efficiency levels. You would not be able to meet those running the motor on Steinmetz.

Robert.

[duncan webster 1]

On duncan webster 1 Said:

Well you’ll have to tell us in which post Robert stated 50%, I’ve just had a quick scan and couldn’t find it. What he did say was that Steinmetz isn’t as good as real 3 phase or a VFD

 

Hi Duncan.
You are correct I never said “Steinmetz only provided 50% of the possible motor power.” as stated by Bob.
I did say:

“The available power is also reduced by around 50% of rating.” in post https://www.model-engineer.co.uk/forums/topic/running-380v-3-phase-motor-on-230v-1-phase/page/2/#post-853111

I stand by this. It’s not great for frequent stop start either. Even Bob says “you never run the machine at 100% load ” post 815862.

I note that we still have not seen a proper circuit of a “converter” that someone has built and run. I also wonder why if Steinmetz is so great why did Bob go to a 3 phase supply.

Robert.

[Barry Smith 4Participant @barrysmith4]

Just as aside one thing that has put me off using capacitors to get 440v 3 phase motors to run in my single phase workshop was the cost and sourcing of a suitable auto-transformer.  At the time I last looked these were significantly more expensive than going down the VFD route, is this still the case?

I must admit that my workshop is unheated, but I have only had 1 problem with a VFD in more than 20 years since I bought my first lathe and installed a VFD (including some second hand and eastern units).  To me the size, variable speeds, and control over starting and braking times have won me over (although I do use a capacitor start, capacitor run for the 1Hp 240v three phase motor on my cold cut saw as per the circuit in No 24 of the work shop practice series).   By the time No 47 came along I had gone down the VFD route …..

[duncan webster 1Participant @duncanwebster1]

This reckons 70 %, but very low starting torque. Also seen reference to motor heating if running close to the max, and non uniform torque output. All references I can find point to less than 90 degree phase shift, which probably explains it.

I’ve also seen circuits which have capacitor over 2 phases and a starting cap, but can’t find the reference just now

[Robert Atkinson 2Participant @robertatkinson2]

Duncan, I think you got the link wrong?

[Robert Atkinson 2Participant @robertatkinson2]

Page 26 of “workshop Practice Series” No.24 “Electric Motors In The Workshop” also indicates that 50% is the most power that can be drawn for any length of time.

Robert.

[duncan webster 1Participant @duncanwebster1]

Oops, here’s what I meant https://www.scribd.com/doc/294923872/6D2F0d01-10-pdf

No need to download the full thing there is a summary box

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

Page 26 of “workshop Practice Series” No.24 “Electric Motors In The Workshop” also indicates that 50% is the most power that can be drawn for any length of time.

Robert.

Workshop Practice Series number 16 by Jim Cox on page 47, para 3.4.3 states ‘with the ‘run’ capacitor fitted …the motor will run and deliver full power’. I don’t believe that, every other internet reference I’ve found states 70% or so.

I wonder if the difference is explained by ‘…for any length of time‘. Lots of sources mention motors running hot. Running at less than 70% would reduce this effect. My one experience of Steinmetz on a grinder spent a lot of its time running unloaded whilst peering at the tool, and when it was working it was still only lightly loaded.

[duncan webster 1Participant @duncanwebster1]

Doubld post removed

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

On duncan webster 1 Said:

Well you’ll have to tell us in which post Robert stated 50%, I’ve just had a quick scan and couldn’t find it. What he did say was that Steinmetz isn’t as good as real 3 phase or a VFD

 

Hi Duncan.
You are correct I never said “Steinmetz only provided 50% of the possible motor power.” as stated by Bob.
I did say:

“The available power is also reduced by around 50% of rating.” in post https://www.model-engineer.co.uk/forums/topic/running-380v-3-phase-motor-on-230v-1-phase/page/2/#post-853111

I stand by this. It’s not great for frequent stop start either. Even Bob says “you never run the machine at 100% load ” post 815862.

I note that we still have not seen a proper circuit of a “converter” that someone has built and run. I also wonder why if Steinmetz is so great why did Bob go to a 3 phase supply.

Robert.

On Robert Atkinson 2 Said:

On Pete Rimmer Said:

On Robert Atkinson 2 Said:

If the Steinmetz connection was an effective method of running electric motors it would be used in industry. It isn’t used in industry as part of the standard design of equipment.  You will always get the odd outlier example but it is not common practice. Show me one piece of commercial equipment that is DESIGNED to run on single phase and uses a 3 phase motor with a Steinmetz connection.

Robert.

 

I’ve already given one example of that. It’s true that I was surprised to find it but the fact remains nevertheless. This was not installed at some tin-pot establishment either it was at a very swanky building in Canary Wharf.

No, you gave me an unsupported anecdote. How do you know it was designed to run on single phase as opposed to being designed for 3 phase and modified for that installation?
Do you have any evidence? Photos of the equipment rating label and motor rating label would do. Make and model of the equipment?

Even domestic electric gate openers use VFDs these days. It makes complying with safety regulations on closing force etc a lot easier.
And don’t forget that 3 phase motors over 750 W now have to meet minimum efficiency levels. You would not be able to meet those running the motor on Steinmetz.

Robert.

You asked for one example of it used in industry, and I gave you one example. I’m not advocating the preferential use of it nor extolling it’s virtues, merely fulfilling your request for an example.

As for being designed for use – of course it was designed. It would not have been supplied or installed otherwise since all such installations must comply with BS EN 12453.

 

[Robert Atkinson 2Participant @robertatkinson2]

You are being awkward or are obtuse. You did not give an example of a piece of equpment. What make? what model number?

I clearly asked “was it designed to run on single phase as opposed to being designed for 3 phase and modified for that installation?” not “was it designed”.

And assuming you didn’t design it, how do you know the motor was a 3 phase type and not a reversible capacitor run type. These are quite common in industry for short duty cycle applications.
Did you look up the motor datasheet?

Robert.

[jimalmParticipant @jimalm]

Mystery solved!

Today we took the motor to a motor-rewinding shop about an hour and a half drive from here and they quickly confirmed that the motor has been professionally rewound to run on 380V 3-phase mains. All the confusion arises because the person who rewound the motor neglected to replace the original 220V nameplate!

Although the motor runs beautifully on 400V, they confirmed it will be far cheaper to replace the motor (with 220V 3-phase) than to change the mains supply in my workshop. Of course I will get a VFD to provide the variable speed.

Once again, I really appreciate everyone’s contributions to solving my puzzle! Thank you all!!

Jim

[jimalm]

On jimalm Said:

Mystery solved!

Today we took the motor to a motor-rewinding shop about an hour and a half drive from here and they quickly confirmed that the motor has been professionally rewound to run on 380V 3-phase mains. All the confusion arises because the person who rewound the motor neglected to replace the original 220V nameplate!

Although the motor runs beautifully on 400V, they confirmed it will be far cheaper to replace the motor (with 220V 3-phase) than to change the mains supply in my workshop. Of course I will get a VFD to provide the variable speed.

Once again, I really appreciate everyone’s contributions to solving my puzzle! Thank you all!!

Jim

Thanks for the update!

Robert.

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

You are being awkward or are obtuse. You did not give an example of a piece of equpment. What make? what model number?

I clearly asked “was it designed to run on single phase as opposed to being designed for 3 phase and modified for that installation?” not “was it designed”.

And assuming you didn’t design it, how do you know the motor was a 3 phase type and not a reversible capacitor run type. These are quite common in industry for short duty cycle applications.
Did you look up the motor datasheet?

Robert.

 

Robert, I’ve nothing more to say to you on the matter. Clearly your ego is unable to allow you to accept opposing views nor plainly made simple statements.

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