Converting Efka 3 phase to single without convertor

[radrider]

Hi all. 
Last week I posted about a couple 291's I picked up with complete old efka variostop motor/control. They have 3 phase and i was curious in how to convert them to single.
The all knowing @Uwe found a page in the 291 instruction manual that seems to hint at the possibility of an internal switching of somethings to convert it to single phase.
I contacted Efka and they said it is indeed possible  and sent a diagram of their own, but in German ...Schiesse!

-

"Attached you find the manual how to change the voltage from 3ph to  single phase. But attention our company didnt take any

warranty if you do that!!!!!! The motor can burn up!!!!!!!!"

Thats OK, I've got an extra motor should this one burn up, and I am planning to purchase new efka servo system in the future.


So my question this time. As I have electrical knowledge somewhere between kindergarten and grade 1, I could use a little pointing in the right direction. (OK thats an understatment)

Ill work on translating the German text to English in the mean time.

 

[Uwe]

More all-googling and all-manual-reading than all-knowing, really.

That German paragraph above reads:

Motors that have serial numbers beginning with 7,8, or 9 start poorly or not at all due to differences in winding paths and rotor geometry (to start these motors a 40μF capacitor would be required, but it would draw a lot of current during idling and heat up.) 

Motors that have serial numbers starting with 10,11, 12 or 6,5,4 have no trouble starting up.

 

My DA467 has an Efka VarioStop setup with 3-phase motor that are apparently a candidate to run nicely on single phase 220V. In North America 220V power supply uses two powered wires (it's different in Europe and elsewhere.) You can hook up those two power wires (L1, L2)  to the terminals that continue on to the control box (red and black wires in the picture below). The terminal with the yellow incoming wire would be empty. You may still need to add a suitable capacitor. I've not yet tried this myself.

Here's a picture of my DA467 Efka wiring box with 3-phase wiring. Single phase wiring would not have the yellow incoming wire.

 

Another option that is less expensive and less bulky than a rotary phase converter would be a static phase converter. It basically does the same capacitor-based third leg generation as in the diagram above to get the motor started. But with a static phase converter you should also make sure that the two original power wires (L1,L2) that are passed straight through are the ones that also go to the control box.

Here's a picture of the inside of my $70 static phase converter, which is essentially a capacitor with some added circuitry and a relay to turn power on and off when the generated third leg is available:

And, just for reference and to illustrate the bulk of what I consider a "proper" rotary setup, here's a picture of my 3HP, 120 lb rotary phase converter setup, which cost me about $600 to put together. I added some displays to check how balanced my three phases are (they balance out nicely during actual use, this is the "idle" picture):

 

Edited February 12, 2018 by Uwe

[radrider]

@Uwe yet again with an amazingly helpful reply, thankyou! 

Also I found out what the "bulge" in the middle of the sewing arm is, it has the ability for a lever to attach that allows manual lifting of the feet, seemingly a very rare addition to a 291 machine(I still have not found any photos of a 291 with this addition, however I saw some 219's with the same attachment)

I owe you big time @Uwe!

Edited February 12, 2018 by radrider

[radrider]

my motor starts with serial number 12! looks like im in luck so far!

tons of "real" sewing work to do today but ill get back ASAP with my progress in converting.

[Uwe]

Disclaimer: Don't blame me if your machine/house/neighborhood goes up in flames while attempting what I describe below. If you have any doubts whatsoever about doing this - DON'T!

I did some testing on my Durkopp Adler 467 setup that uses an Efka motor and control box that is similar to what is on the DA 291 pictured above. I already had a static 3-phase converter made by American Rotary (1/2-3HP rating, $65). I wanted to see if it would power the machine.

Executive summary: The machine did power up, the motor also spun right up. No electrical smell/smoke/fire/explosion.

Unfortunately I wasn't really able to test the machine during normal use since it was sitting in my 40˚F garage and its joints were stiff (as were mine.) So, while initial results are encouraging, I don't yet have full confidence in this setup until I can test it fully under normal operating conditions.

I added a 2-pole switch to disconnect the power from the 3-phase converter when not in use.

Do NOT connect the plug to the wall outlet until you are positive that all the wiring is correct! 

Here's a wiring schematic of how I connected the pieces:

 

 

The actual real-world wiring looks a little messy. I hope the annotations help: 

I did swap T1 and T2 wires inside the 3-phase converter to change the rotation of the motor. You will read in many places that to change the rotation of a 3-phase motor, you can swap any two wires. The only two wires you are allowed to swap in this scenario with a static phase converter is T1 and T2! Otherwise you will send crappy T3 power to the control box and it may die. With static phase converters T3 can only be used to help get the motor spinning!

Since there are no guarantees how wiring runs through the machine's on-off switch, you can't count on wire colors matching up end-to-end. You really have to verify which wire in the phase converter (T1,T2,T3) matches up with which wire (L1,L2,L3) in the wiring box on the motor. I turned on the machine's on/off switch, disconnected the wires (T1,2,3 inside the phase converter and L1,2,3 in the motor connector box) and used a multimeter to check continuity between wire ends to positively identify which wire goes where. Of course I did all this before I ever connected to the wall outlet!

Edited February 18, 2018 by Uwe

[Gregg From Keystone Sewing]

On 2/17/2018 at 11:57 PM, Uwe said:

Disclaimer: Don't blame me if your machine/house/neighborhood goes up in flames while attempting what I describe below. If you have any doubts whatsoever about doing this - DON'T!

I did some testing on my Durkopp Adler 467 setup that uses an Efka motor and control box that is similar to what is on the DA 291 pictured above. I already had a static 3-phase converter made by American Rotary (1/2-3HP rating, $65). I wanted to see if it would power the machine.

Executive summary: The machine did power up, the motor also spun right up. No electrical smell/smoke/fire/explosion.

Unfortunately I wasn't really able to test the machine during normal use since it was sitting in my 40˚F garage and its joints were stiff (as were mine.) So, while initial results are encouraging, I don't yet have full confidence in this setup until I can test it fully under normal operating conditions.

I added a 2-pole switch to disconnect the power from the 3-phase converter when not in use.

Do NOT connect the plug to the wall outlet until you are positive that all the wiring is correct! 

Here's a wiring schematic of how I connected the pieces:

 

 

The actual real-world wiring looks a little messy. I hope the annotations help: 

I did swap T1 and T2 wires inside the 3-phase converter to change the rotation of the motor. You will read in many places that to change the rotation of a 3-phase motor, you can swap any two wires. The only two wires you are allowed to swap in this scenario with a static phase converter is T1 and T2! Otherwise you will send crappy T3 power to the control box and it may die. With static phase converters T3 can only be used to help get the motor spinning!

Since there are no guarantees how wiring runs through the machine's on-off switch, you can't count on wire colors matching up end-to-end. You really have to verify which wire in the phase converter (T1,T2,T3) matches up with which wire (L1,L2,L3) in the wiring box on the motor. I turned on the machine's on/off switch, disconnected the wires (T1,2,3 inside the phase converter and L1,2,3 in the motor connector box) and used a multimeter to check continuity between wire ends to positively identify which wire goes where. Of course I did all this before I ever connected to the wall outlet!

This is excellent information, well done UWE

[Willbury]

This is a really helpful thread!  I was pleased the see the controller is 2 phase as it looks like the static phase converter should work.

I have been debating picking up one of these and finally did the long drive down, from Ottawa,  and picked up two 291’s (with the bottom knuckle)from the factory  yesterday.  

What’s left is getting pretty picked over, but I believe I got two very good machines. No play in the needle bar at least.

Will post some pics when I get a chance.