Need help with 3Phase Wiring Diagram.

[tim_callinan]

Im a mechatronics instructor at a local community college. I have a couple of motor control questions and would definitely appreciate any help. Ive enclosed a wiring diagram of the 3 phase motor we are using in our labs. Can I assume from this diagram that the motor is wired in a Wye configuration?

The second question is our lab has 3 phased wired to it. Each phase has 120V and 208 across phases - I would assume with this setup I would wire the motor in the low voltage configuration. Also if I was in Europe and each phase was 240V - I would wire it in the high voltage config?

I like to have a backup project for some of my eager students and we're going to be using the powerflex 525 VFDs. I have a load of panelview HMIs lying around also. Is it possible to directly control the 525s using the panelviews without a PLC? Some of my students might not have used a PLC yet so I cant really use the PLCs in this course.

Any advice is defo appreciated. Thank you for all the help.
Tim

 

[I_Automation]

Yes, that motor is a Wye configuration.


The low vs high voltage would be on the motor nameplate and there are many different ratings.


Commonly low is 240 and high is 480, but it could be 220-380 (European) and other voltages.


If the motor is rated for 220 or 240 for the low voltage 208 might be too low and cause problems. If you are using VFD's make sure the VFD input includes 208 volts. It could say 208, 208-240 or 200-250. If it says 220-240 then it will have problems being run on 208 volts, and depending on the VFD might fault out on undervoltage and not run at all.


Since I'm not a PanelView expert that part I'll leave to someone here that does know.

 

[tim_callinan]

Thank you I-Automation! From the motor nameplate it says Voltage: 208-230/460V AC.
Now is that 208 per phase or across phases? B/C all im getting is 115V per phase in my lab?
The motor definitely runs and with a VFD. There will be no load on the motor anyway - its just for labs, etc.

I get the Low/High voltage wiring drawings. They make sense to me but I'm a little confused with Delta/Wye.
Why is that motor originally wired up in a WYE configuration. Would there be any reason to modify it and wire it up in a Delta config?
Im trying to teach an introductory course on motors and control. Is getting into Delta Vs Wye too deep for such a course?
Thank you for the advice!
Tim

 

[I_Automation]

If you have a 3 connector plug (not counting the ground) that reads 208 A to C and 115 A to B and B to C that is only grounded-neutral single phase power.



Three phase would be 208 between any 2 of the 3 power pins, and could include a neutral pin, along with the ground pin. Then each power pin to neutral or ground would be 115 volts.



If you only have single phase some VFD's are single phase input with 3 phase output, and some 3 phase input VFD's will operate on single phase power at a reduced capacity. PowerFlex VFD's run on single phase are to be derated 50%, so a 3 HP VFD would then run a 1-1/2 HP motor, and there is a Phase-Loss parameter that faults if a phase is low or off that needs turned off to run on single phase.


As far as modifying the motor to Delta it would need rewound, which I have found is $600 minimum per motor when you can buy a new one for under $125 if you look around. The Wye vs Delta reason is they have different performance characteristics for applications.

 

[jaden]

A good text reference for a course like yours is Electrical Motor Controls by Rockis & Mazur.