Powering three-phase skiver motor

[Digit]

Hi all,

I've just bought an old bell skiver (Fortuna) powered by a three-phase clutch motor. I don't have three-phase power at home, so now I'm looking at possible options to get this machine running.

Option one: replace the clutch motor with a servo. This comes with the downside of losing the vintage esthetics and the need to get the servo motor speed-calibrated correctly.

Option two: buy a variable frequency drive (VFD) to convert single-phase to three-phase to power the motor. This also loses a little bit of the vintage esthetic, but the VFD can be hidden under the bench more easily I guess.
For this option I have two directions to go in. The clutch motor states 220/380V, so that means it can be hooked up to either a three-phase 220V supply when connected in Delta, or to a three-phase 380V supply when connected in Wye.
Searching for VFDs I find both 1p/220V-to-3p/220V units and 1p/220V-to-3p/380V units. When I use the former I'd have to connect the motor in Delta, when I use the latter I need to connect it in Wye.
Does one or the other have a preference? Can VFDs be used for either Delta or Wye connection or do they assume one of the two?

[Cumberland Highpower]

I am curious, are clutch motors an easy thing to find in Belgium?  If they are, why not just change it to something single phase?

I've probably purchased maybe 20 machines so far that were set up for 3ph clutch motors, and on almost every one of those, I swapped the 3ph motor for a single phase.

Used Clutch motors here are usually $20-50. In the US that makes them cheaper on the used market than a good VFD, and you don't have to do any work around other than a little with the wiring.

Most motors like that are designed for delta on the lower and Wye on the higher voltages.  You're not planning to install on 380v are you?  I'm guessing not?

Your VFD will wire up as a delta 220v.

Every 3phase machine I have that didn't get converted by a motor swap is run off of a rotary phase converter, wired delta.   Everything from Clickers, to Band Skivers, Belt cutting machines, CNC stitchers, bell skivers, etc. Often several at once.

You could also just add a capacitor to your motor and effectively convert it to run on single phase, but it's been a long time since I've done that so you'll have to research..

Some factory built machines come like that, for example my FAV bell skiver has a 3ph motor with a run and start capacitor added to make it "insta" single phase).

There are ready made static converters that do the same thing, they're just a box with capcitors and your motor would run at 2/3 power once it starts up. Static converters seem to be fading away with the VFD being around.

 

 

[Dwight]

Toss the esthetics out the window . . . get a cap start single phase motor . . . and go to work.

Quickest . . . cheapest . . . and actually THE best way . . . as there are downsides to ANY other option . . . and the only down side to this one is you haven't done it yet.

May God bless,

Dwight

[Tigweldor]

Hi,

The old clutch Motors are not bad units. Even if 3 phase, you can run them on single phase power if you use a VFD (Variable frequency device / Frequenzumrichter).

Now the VFD units only convert 230Volt single phase to 230 Volt 3-phase - they can NOT convert 230 Volt single phase to 380 Volt 3 phase

For that, you have to open the little electrical box on the motor.

You will find the 3 connections for the lines coming in (usually numbered R, S, T )

When poled/set up for 380 Volts - you will find that 3 of the other poles are bridged with each other (usually marked U , V, W))

You can remove these bridges and and then bridge each pair of poles individually = R to U , S to V , T to W )

Now you can run the three phase motor on 230 Volt single phase power with a VFD.

This is actually the best way to run a 3 phase motor on single phase - plus you can alter some of the characteristics of the motor like : increased starting current - a motor brake for instant stop - top speed by dialing in the frequency.

A new VFD costs around 60€ to 100€ on Ebay (ebay.de) - the cheap ones do come from China.

 

I run all my machines on VFD - but I get them used from Kleinanzeigen (craigs list in Germany).

The bonus of getting a good used VFD is that the Chinese units have a cooling fan that runs at all times - the better units only start the cooling fan when needed = less noise.

 

Hope to have helped you - if not, I can draw a diagram to boot.

 

Greetings

Hans

Edited March 22 by Tigweldor

[Cumberland Highpower]

9 hours ago, Dwight said:

Toss the esthetics out the window . . . get a cap start single phase motor . . . and go to work.

Quickest . . . cheapest . . . and actually THE best way . . . as there are downsides to ANY other option . . . and the only down side to this one is you haven't done it yet.

May God bless,

Dwight

That was my idea as well Dwight.   But, I have to say that's probably a pretty well built quality clutch motor he has there!   I have a single phase CM made in Belgium here (3450rpm ) and it's a pretty well built unit.  Wish I had more of those. It came on an Adler made in the late 60s so it has some age to it.

[Northmount]

Induction motors are designed to provide enough cooling air to keep the motor at a safe temperature in a range of ambient temperatures.  If you run them on a VFD at low speeds, depending on the motor and the load, you can get to the point where the motor no longer has the required cooling air flow.  (There is more documentation on larger motors, 25 hp and up than there is on small motors.)  The motor also has less available torque at low speeds, is more inefficient further increasing its temperature.  If you monitor the temperature of the motor, you should be safe.  You should be able to place your hand lightly on the motor for 5 to 10 seconds.  If you can't, it is getting too hot.  Either speed it up for more cooling, or shut down until it has cooled.

 

[Digit]

Thank you all for the replies.

Belgium is basically the sticks in the electro/mechanical field. Labour is so expensive over here that most small industries have moved away or went out of business decades ago and the associated tools have been sold off or scrapped. I'm also under the impression that over here there is very little interest in tinkering with stuff; that means there's not much of a second-hand market (complete machines or loose components) or scrap yards where you can find parts.
The skiver I've bought was actually a rare find, especially given its age. It was used by a now retired shoemaker and his successor prefers to use a more modern machine and sold this one. I've tested it in the seller's workshop and I was surprised by the reasonable quietness of the motor and the suppleness of the clutch.
The plate on the motor mentions the factory in Leinfelden which, according to the company's website, started in 1960. From 1985 they started making servo motors. Given this info and the motor's build quality I guess it must have been made somewhere in the sixties.

I'm not planning to install 3-phase power just yet. In Belgium there's 3ph arriving in most homes, but historically only one phase was hooked up and the utility companies alternated phases between houses to get them balanced. With the advent of electric cars and solar panels, new houses are more likely to get a proper 3-phase connection. Upgrading an existing single phase connection to three phases costs nearly as much as I paid for this skiver and would additionally require an inspection of the full electrical installation, which isn't free either.
Since there is an abundant supply of three-phase power in Belgium (albeit with a price tag), even to remote areas, and there has been for decades, there is no market for rotary phase converters (new or second hand).

@Cumberland Highpower I know I can run a three-phase motor on single phase using a Steinmetz connection (capacitors), but it's not very efficient and could risk overheating the motor by running it underpowered.

@Dwight I get what you're saying and it would make sense from a business perspective. However I do this as a hobby and for the moment I can still use the skivers at school, so there's no real pressure to get mine working. Also, contrary to most other Belgians, I do like to tinker with stuff and try things out.

@Tigweldor as I understand it, VFDs use an inverter to rectify incoming AC to DC and then produce simulated AC by pulsing DC (PWM) on successive phases; this pulsing can produce an audible whine in the motor, which you can reduce by tuning the carrier frequency. The VFD can produce 380V if it includes a step-up-converter in the DC line.

@Northmount I have no intention to run the motor on a different speed than it was made for, so cooling shouldn't be a problem as long as I vacuum the accumulated dust from the motor's grill. Anyway, the clutch allows me to tune the speed of the skiver using the pedal.

To conclude, I've ordered a single-phase 230V to three-phase 380V Chinese VFD and I'll see where that gets me. I'll keep you guys updated.

 

[Tigweldor]

Hi Digit,

 

Please send link of the VFD that you ordered.

 

Greetings

Hans

[Digit]

23 minutes ago, Tigweldor said:

Please send link of the VFD that you ordered.

The .75kW one of this listing: https://www.aliexpress.com/item/1005007944151596.html

[Tigweldor]

That is one hell of a good price - less than they charge for a single cocktail in a bar here in Germany.

Heck, with that price it doesn´t matter that the item comes from Chinesistan.

Good deal.

Edited March 24 by Tigweldor