Advice for connecting a Metba MB-0

dmarthur · Jul 26, 2022

Hi everybody,

I just purchased a Metba MB-0 for my home shop. It is a 380V 3-phase machine and I currently have 220V single phase power running to my house. Reading through the forums it seems that it is common to use a VFD directly to the motor and basic on/off switching with the VFD as well. All of the other ancillaries (e.g. coolant pump, table drive motor) are wired directly to the 220V single phase.

Is that right? I would very much like to find a way to keep the original controls, and electrical cabinet that came with the machine, but I am a complete rookie when it comes to this and would really appreciate some guidance here.

Kind regards,
David

Luke Rickert · Jul 26, 2022

That looks like an interesting machine.
Location would be helpful here.
That picture is in Europe so if it is your machine I would look into paying for the 3phase upgrade if at all possible. In the US I would suggest a rotary phase converter. If you can't get three phase then rewiring everything with a VFD is the best option. (you might need a transformer as well)

Luke

dmarthur · Jul 26, 2022

Hi Luke,

Thanks a lot for the quick reply. I am living in Spain so it is possible for me to get a 3 phase line to the house but I had understood it would be prohibitively expensive as it also requires a minimum guarantee of power purchased per month.

If I am not able to get the 3 phase to the house, would I rewire only the motor to the VFD, or is it possible to connect the entire electrical cabinet directly to the VFD?

Apologies if these are completely obvious questions but this is my first go. Also, I see you're in Oslo -- I lived there for 6 years and absolutely loved it.

Cheers,
David

Luke Rickert · Jul 26, 2022

dmarthur said:
Hi Luke,

Thanks a lot for the quick reply. I am living in Spain so it is possible for me to get a 3 phase line to the house but I had understood it would be prohibitively expensive as it also requires a minimum guarantee of power purchased per month.

If I am not able to get the 3 phase to the house, would I rewire only the motor to the VFD, or is it possible to connect the entire electrical cabinet directly to the VFD?

Apologies if these are completely obvious questions but this is my first go. Also, I see you're in Oslo -- I lived there for 6 years and absolutely loved it.

Cheers,
David

You should wire the VFD to the motor directly without switches etc in line. I did this with one of my machines before I moved to a location with 3 phase and it wasn't so hard to setup. (I had a Schaublin 102 and a Rumag mill in the basement of my rented apartment in Frogner in Oslo which was unusual for that area

I know a guy in Manresa (so not too far from you) who has done this to his machines probably for the same reasons of power availability. I can put you in touch if that would be helpful. I wonder if Spain is like France where an upgrade to three phase was expensive (6k euros because of the trench on public property) but a new connection with three phase was only 1300 or so.

Luke

dmarthur · Jul 26, 2022

Wow it's a small world -- I live in the village next to Manresa! I'd be hugely appreciative if you wouldn't mind an intro to the guy you know and who may be able to help me out. My email address is my username @ fastmail dot com.

I think you may be right regarding new vs existing installation prices. A lot of the houses near me opted for three phase 380 V when they were built and their bills don't seem a lot higher than mine.

Cheers,
David

Luke Rickert · Jul 26, 2022

dmarthur said:
Wow it's a small world -- I live in the village next to Manresa! I'd be hugely appreciative if you wouldn't mind an intro to the guy you know and who may be able to help me out. My email address is my username @ fastmail dot com.

I think you may be right regarding new vs existing installation prices. A lot of the houses near me opted for three phase 380 V when they were built and their bills don't seem a lot higher than mine.

Cheers,
David

You have an email David.

A small world indeed, my workshop and project houses are on the French side of the Pyrenees, about two and a half hours by car from Manresa (although it isn't so far in a straight line those roads are not very fast). I will let you know when I am down there next if you want to visit.

dmarthur · Jul 26, 2022

Luke Rickert said:
You have an email David.

A small world indeed, my workshop and project houses are on the French side of the Pyrenees, about two and a half hours by car from Manresa (although it isn't so far in a straight line those roads are not very fast). I will let you know when I am down there next if you want to visit.

Thanks a lot. And please let me know next time you’re down. It would be great to meet up.

AlfaGTA · Jul 26, 2022

The general rule for VFD's is that you should not switch any power out of the unit.
All on/off needs to be handled by the VFD itself. Which means that original contactors and switches that control the4 main drive motor can't be used as is.
They should be re-wired so that the switches control the VFD's control inputs.

Further is that machine has additional 3 phase motors (feed, coolant) those should not be combined with the main motor's VFD...One per motor is the general rule.

Any additional electrical equipment like the DRO will likely have settings that allow use on your native single phase feed. Have to look at the specific device to know for sure.

A rotary converter ca be used to supply all machine functions just like (kind of) having true 3 phase power at your shop.
Some down sides to rotary's: They can be noisy , an additional idler motor running when the supply is needed. They can be an additional source of heat in the shop, could be good or not.....
You will need a transformer to "boost" the supply of 220v to the required 380 needed for your motors.

3rd choice here; There is a true industrial phase conversion system. Not sure its available in Europe....
Designed to run inductive loads (motors) and will handle any number of feeds (devices) up to the rated power of the selected converter....
Called "Phase Perfect" it can supply 3phase power to an entire shop . virtually silent and draws almost zero power in standby.....
Bit costly, but solves the 3 phase power needs in one shot.....No machine rewiring needed, all controls work as original.
Would need a transformer on the output to give the 380 form your 220 supply...On the PP voltage in = voltage out.
Can be had with an enclosure that is weather tight to allow mounting outdoors to save space in the shop....

Phase Perfect | 3 Phase Power Anywhere With Our Digital Phase Converter

Three-phase power from a single-phase source anywhere you need it. Phase Perfect® digital phase converter uses modern solid-state electronics to create utility-quality three-phase power anywhere. Over 20 years of development has resulted in a robust and durable phase converter capable of...

www.phasetechnologies.com

Cheers Ross

dmarthur · Jul 26, 2022

AlfaGTA said:
The general rule for VFD's is that you should not switch any power out of the unit.
All on/off needs to be handled by the VFD itself. Which means that original contactors and switches that control the4 main drive motor can't be used as is.
They should be re-wired so that the switches control the VFD's control inputs.

Further is that machine has additional 3 phase motors (feed, coolant) those should not be combined with the main motor's VFD...One per motor is the general rule.

Any additional electrical equipment like the DRO will likely have settings that allow use on your native single phase feed. Have to look at the specific device to know for sure.

A rotary converter ca be used to supply all machine functions just like (kind of) having true 3 phase power at your shop.
Some down sides to rotary's: They can be noisy , an additional idler motor running when the supply is needed. They can be an additional source of heat in the shop, could be good or not.....
You will need a transformer to "boost" the supply of 220v to the required 380 needed for your motors.

3rd choice here; There is a true industrial phase conversion system. Not sure its available in Europe....
Designed to run inductive loads (motors) and will handle any number of feeds (devices) up to the rated power of the selected converter....
Called "Phase Perfect" it can supply 3phase power to an entire shop . virtually silent and draws almost zero power in standby.....
Bit costly, but solves the 3 phase power needs in one shot.....No machine rewiring needed, all controls work as original.
Would need a transformer on the output to give the 380 form your 220 supply...On the PP voltage in = voltage out.
Can be had with an enclosure that is weather tight to allow mounting outdoors to save space in the shop....

Phase Perfect | 3 Phase Power Anywhere With Our Digital Phase Converter

Three-phase power from a single-phase source anywhere you need it. Phase Perfect® digital phase converter uses modern solid-state electronics to create utility-quality three-phase power anywhere. Over 20 years of development has resulted in a robust and durable phase converter capable of...

www.phasetechnologies.com

Cheers Ross

Thanks so much for such a comprehensive explanation Ross. I’d really like to try and keep the machine and cabinet as-is so sounds like I’ll need an actual 3 phase installation, or the rotary converter, or one of those Phase Perfects, which seem really cool.

What a great forum this is — I’ve had great replies from you and Luke on the same day and know a lot more about how to tackle this than I did 12 hours ago.

Cheers,
David

Peter from Holland · Jul 27, 2022

The Metba has a 2-speed single voltage motor
Another option is to swap the motor with a single speed dual voltage motor
Then set the motor for 220 volts (3phase that is) Delta that is And then use a VFD with 220 volts single phase input and 220volts 3ph output
These VDF `s are available on the used market over here The motor also probably
Beter buy a used decent brand VFD than a new cheap chinese IMHO

I would not bother with the coolant pump. I never use coolant anyway

Peter

dmarthur · Jul 27, 2022

Peter from Holland said:
The Metba has a 2-speed single voltage motor
Another option is to swap the motor with a single speed dual voltage motor
Then set the motor for 220 volts (3phase that is) Delta that is And then use a VFD with 220 volts single phase input and 220volts 3ph output
These VDF `s are available on the used market over here The motor also probably
Beter buy a used decent brand VFD than a new cheap chinese IMHO

I would not bother with the coolant pump. I never use coolant anyway

Peter

Thanks a lot Peter. I agree that I’ll start without the coolant pump as well as I don’t think I’ll need it for the sort of work I’ll be doing.

I didn’t know that about the motor being two speed though. I thought all speed adjustment took place by swapping the belt between different sets of pulleys. I’ll take another look this afternoon.

Cheers,
David

dmarthur · Jul 28, 2022

Hi again everybody,

I had previously — before asking the question in this forum — arranged for an electrician to come by and try a VFD combined with a transformer. He came out today and wired it up as follows:

230 V single phase -> VFD simulating 230 V three phase -> 230 V three phase to 380 V three phase transformer -> electrical cabinet of Metba MB-0.

When I tested the motor seemed to turn the spindle with no problem, even using the original control panel. However the table traverse motor seemed to move the table in a non-continuous manner which was especially evident at low speeds.

My question to you gentlemen here is whether I risk damaging anything with this setup? I understand now that it is best practice to connect the VFD directly to the motor and, further, to connect the controls directly to the VFD as well. But is there some sort of risk associated with the set up I describe above? If so I won’t go ahead with it and work on one of the alternatives that have been described above.

Cheers,
David

Peter from Holland · Jul 28, 2022

If it has a potmeter to controle speed of the feed it is a dc motor That generates another problem What is the powerfeed tothe driver of that Dc motor And what kind of dc motor Abb/bbc pancake perhaps??A electrical diagram would help

dmarthur · Jul 29, 2022

Here are the relevant (I think) pages from the manual that came with it.

Peter from Holland · Jul 30, 2022

Wire M6 0V to neutral and 220V to your 220volts phase and the powerfeed should work on 220 volts single phase IMHO

Peter

dmarthur · Jul 30, 2022

Peter from Holland said:
Wire M6 0V to neutral and 220V to your 220volts phase and the powerfeed should work on 220 volts single phase IMHO

Peter

Thanks Peter. I will give this a shot.

dmarthur · Aug 5, 2022

dmarthur said:
Thanks Peter. I will give this a shot.

Hey Peter,

Just to let you know that I tried this and it works. Thanks for the tip!

Cheers,
David

Peter from Holland · Aug 5, 2022

Thanks for letting us know
Does it have a sigle speed motor or a 2speed ???
Curious
Peter

dmarthur · Aug 5, 2022

The spindle motor is 380 V and two speed. The table traverse motor is DC, as you suspected, and I’ve attached a pic of the motor plate.

Cheers,
David

dmarthur · Aug 5, 2022

dmarthur said:
The spindle motor is 380 V and two speed. The table traverse motor is DC, as you suspected, and I’ve attached a pic of the motor plate.

Cheers,
David

Also, Luke, thanks for the intro to Sebastià! He popped over today to walk me through the machine and wiring diagrams.

Advice for connecting a Metba MB-0

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