Motor leads

[The Learner]

Hey guys,

So I need to wire this motor and I’ve enclose a picture of what they’re asking me to do. Does it seem logical that I would simple parallel these leads together?
1, with 7, 6, 12
2, with 4, 8, 10
3, with 9, 5, 11
I’ve never seen this done this way before so just want to make sure it’s right. The voltage is 3phase 208v.

Thanks

 

[don_resqcapt19]

That is the correct wiring for a 12 lead 3 phase delta connected motor on the lower voltage. If you draw it out you will see that there are two deltas. If you draw out the high voltage you will see a single delta.

 

[don_resqcapt19]

What is the name plate voltage? Typically a delta motor will be 240/480, and may not be suitable for use on a 208 volt system.

 

[kwired]

The fact it mentions wye-delta starting is part of why they have 12 leads.

Otherwise many times 10, 11, and 12 are internally connected to 2, 3 and 1 and only one common conductor is brought out for each of those field connections, in that case it couldn't ever be wye connected.

 

[The Learner]

Thank you guys. I’ll look at the rating of the motor today. Thanks again

 

[retirede]

What is the name plate voltage? Typically a delta motor will be 240/480, and may not be suitable for use on a 208 volt system.

Good question. It may be tri-voltage. Low voltage 240 is usable at 208.

 

[kwired]

Good question. It may be tri-voltage. Low voltage 240 is usable at 208.

If your 208 nominal runs on the high side, around here no load voltage is often 212-216, you are still within 10% of nameplate rating which is usually 230. Should the motor be lightly loaded that also helps lessen overheating

 

[The Learner]

So the motor rating said 230/460 volts but also said for 208 bolts. I never saw that before

 

[retirede]

If your 208 nominal runs on the high side, around here no load voltage is often 212-216, you are still within 10% of nameplate rating which is usually 230. Should the motor be lightly loaded that also helps lessen overheating

If the nameplate says 208, it is supposed to work at a nominal 208 volts.
The 1.15 SF tri-voltage motors we used to use stated “1.0 SF at 208V” right on the nameplate.

 

[Jraef]

So the motor rating said 230/460 volts but also said for 208 bolts. I never saw that before

Then yes, if the motor nameplate says it is usable at 208V, then you would connect it the same as 230V.
Tri-voltage (208-230.460V) motors are quite common for 10HP and below. The design philosophy is that most 208V installations are light commercial buildings, so it's unlikely there will be a long distance from the service to the motor, as there might be in industrial applications. So not that it is 208V, not 200V. The standard "utilization voltage" design for a 208V system would be 200V, just like 230V motors are for 240V systems and 460V motors are for 480V systems. But on a tri-voltage motor, it IS actually 208V, not 200, so if the actual voltage is a lot lower, it may be problematic.

There is a very good treatise on this in "The Cowern Papers", published by Baldor back when they were still Baldor.

http://irtfweb.ifa.hawaii.edu/~tcs3/tcs3/Misc/about/motor_basics.pdf

This part starts on page 53 (but the entire paper is excellent reading for understanding motors).