6 Wire Motor Wiring - Check me?

[jtcrowder49]

Hi All,

Working on getting my new to me mill going. I had thought I had gotten this figured out but I thought about it too long and I think I confused myself. Since It will be difficult to find another motor I want to get some additional opinions from the group here before applying the power.

I have the motor pictured below. This motor was previously wired to 3 phase and the drum switch was quite complex allowing Hi and Low in FWD and in Reverse. Since I am changing to a VFD, I am trying to make sense of the motor wiring/ I expected to see 9 lugs but I have since learned this is only a 6 wire motor.

Am I correct in assuming I need to "bridge" or "short" the W1V1U1 legs and then apply the VFD output to the W2, V2, U2 legs?

Is there a preferred material for making shorting bars? Or is wire and crimp eyes good enough?

It's hard for me to tell since the other schematic is a little damaged. I am supplying a 220v to the VFD if that makes any difference.

edit: Does 2P or 4P operation make a difference for me? Does one do something the other does not?

Also edit: I have been referencing this article, but I am unclear since the voltage on the motor plate is the same for both wirings?

Three-Wire vs. Six-Wire Three-Phase Motors - Technical Articles

Three-phase motors with three or six wires have limited options for wiring, but are easier to use and have important roles to play. Learn the difference between three- and six-wire three-phase motors for low and high voltage applications.

control.com

 

[Karl_T]

2p means two pole or 3600 rpm
4p means four pole or 1800 rpm.

It will run on the 2p wiring shown on the left.
the 4p would be better - more torque. Then use the VFD to 120 Hz to get 3600 rpm. I cannot quite make out the connections from the pic.

They make little copper jumpers for these two speed motors, guess yours are lost. fab what ever you can - need to do it so it does not over heat from current flow. if you can not make out the right wiring, i think my vectrax has the same plate.

 

[Karl_T]

read this page from my vectrax build. my machine - bottom connections were four pole

Vectrac CNC Knee mill refit from Fanuc 0M to Camsoft

I've had a really nice Vectrac CNC knee mill with a Fanuc 0M control for quite some time. Great machine, but the old control is kludgy and impossible to maintain. Time to upgrade it. This will be my fifth machine refit to Camsoft controls. My goal is to make this one the best yet. The real...

www.hobby-machinist.com

Your motor wiring is likely different. If you still have the drum switch wring out the correct connections. if not, you may have screwed yourself.

 

[jim rozen]

The article referenced does not really describe your particular motor. I believe yours is a 'consequent pole' motor, and if so you should probably wire it in the 'two pole' (higher speed) cofiguration, as you suggested in your post. If it is consequent pole then it will be half the hp rating on the lower speed, so use the higher speed for the VFD use.

How to tell if it is consequent pole: If all leads have continuity with all other leads, it is.
However if the "1" windings are isolated from the "2" windings it isn't, and in that case use the lower speed configuration.

 

[BT Fabrication]

Hi All,

Working on getting my new to me mill going. I had thought I had gotten this figured out but I thought about it too long and I think I confused myself. Since It will be difficult to find another motor I want to get some additional opinions from the group here before applying the power.

I have the motor pictured below. This motor was previously wired to 3 phase and the drum switch was quite complex allowing Hi and Low in FWD and in Reverse. Since I am changing to a VFD, I am trying to make sense of the motor wiring/ I expected to see 9 lugs but I have since learned this is only a 6 wire motor.

Am I correct in assuming I need to "bridge" or "short" the W1V1U1 legs and then apply the VFD output to the W2, V2, U2 legs?

Is there a preferred material for making shorting bars? Or is wire and crimp eyes good enough?

It's hard for me to tell since the other schematic is a little damaged. I am supplying a 220v to the VFD if that makes any difference.

edit: Does 2P or 4P operation make a difference for me? Does one do something the other does not?

Also edit: I have been referencing this article, but I am unclear since the voltage on the motor plate is the same for both wirings?

Three-Wire vs. Six-Wire Three-Phase Motors - Technical Articles

Three-phase motors with three or six wires have limited options for wiring, but are easier to use and have important roles to play. Learn the difference between three- and six-wire three-phase motors for low and high voltage applications.

control.com

NOOOOO dont short the 1's unless you want to see sparks or trip the breaker ! only the 2 side for 2P 4 P you keep them seperate and it is connected in the motor internally.

the 1's are where all the incoming power hooks to.

 

[jtcrowder49]

read this page from my vectrax build. my machine - bottom connections were four pole

Vectrac CNC Knee mill refit from Fanuc 0M to Camsoft

I've had a really nice Vectrac CNC knee mill with a Fanuc 0M control for quite some time. Great machine, but the old control is kludgy and impossible to maintain. Time to upgrade it. This will be my fifth machine refit to Camsoft controls. My goal is to make this one the best yet. The real...

www.hobby-machinist.com

Your motor wiring is likely different. If you still have the drum switch wring out the correct connections. if not, you may have screwed yourself.

I still have the drum switch wired correctly and I took photos before disassembly. How might this help me?

 

[jtcrowder49]

The article referenced does not really describe your particular motor. I believe yours is a 'consequent pole' motor, and if so you should probably wire it in the 'two pole' (higher speed) cofiguration, as you suggested in your post. If it is consequent pole then it will be half the hp rating on the lower speed, so use the higher speed for the VFD use.

How to tell if it is consequent pole: If all leads have continuity with all other leads, it is.
However if the "1" windings are isolated from the "2" windings it isn't, and in that case use the lower speed configuration.

I have confirmed that all lugs have continuity with each other via multimeter.

 

[Jraef]

Ok, that is an oddball motor, or something is amiss with the nameplate.

With 2 speed motors, there are two types: 2spd 2winding and 2spd 1winding. In 2S2W, the speeds and HP ratings can be whatever someone wanted so long as they were willing to pay for it and live with the physical size if the frame to make it work. For the most part, IEC motors (like yours) are not going to be 2S2W. The IEC world uses what’s called a “Dahlander motor” configuration, which is 2S1W.

With 2S1W there are 3 different designs, Constant Torque, Variable Torque and Constant HP. In those, you can always tell which it is by the nameplate values: with CT the low HP is half of the high HP, with VT the low is 1/4 if the high, and with CHP the HP is the same at both speeds. Your nameplate would imply CHP, because it only lists the one HP value at both speeds.

Here are diagrams.

3Ph Motors, 2 Speed, Single Winding

Terminal Markings and Connections Three-Phase Motors-Two Speed Single Winding NEMA Nomenclature - 6 Leads Constant Torque Connection Low-speed horsepower is half of high-speed horsepower.*

joliettech.com

The odd part however is that there is no IEC diagram for a 2S1W Constant HP configuration. It might be that they built it to the NEMA diagram for CHP, but used IEC termination numbering. Either that, or they messed up the nameplate by failing to list the HP value at low speed.

 

[jim rozen]

Probably the nameplate is 'simplified' (hp rating is stamped in a different font?) and this is indeed a two speed consequent pole motor. They're lower power on the lower speed so the typical drill is:

1) hardwire for high speed use.
2) connect VFD and this allows full power operation, and allows lowering speed to imitate the low speed configuration.

Although the current draw specs suggest is indeed same hp for both speeds, nearabout.

 

[jtcrowder49]

Thank you both for the information.

Based on this discussion. I should follow the diagram as indicated in my first post?

Short U1V1W1 and apply VFD output to U2, V2, and W2?

 

[jim rozen]

That will put the motor in high speed range.

 

[jtcrowder49]

That will put the motor in high speed range.

Thank you. I apologize I just wanted to make sure I was clear since there was a conflicting answer above. I appreciate the help.

 

[jim rozen]

The deeper issue here is which speed is best to operate the machine via VFD - typically consequent pole motors are constant torque so those will lose power when run on slow speed configuration. The nearly identical current draw (hi vs low) on your motor suggests it's an unusual type, and it's possible the best speed selection might be better determined by what speed you will mostly run the machine at. I confess the notion of a constant hp consequent pole motor is outside my experience, so other posters might give a better answer.