460V 12-lead motor - proper wiring?

[MrJLH]

The rest of the notes from that project, switching 12) wye/delta motors from low volt to high volt and changing the overload relays to suit.

Take special note of the second drawing, where it says to swap the winding connections, when using the wye/delta control, otherwise the motor will change directions at the switchover, at full speed. Could be ugly on a large motor.

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Thank you for this.

I have a cooling tower fan that uses a run forward/ run reverse setup that was built in the 50's using a similar set up as sketched with the three starters. I have no wiring diagrams and every component is in its own NEMA 7/9 enclosure.

 

[MD Automation]

FWIW the delta diagram on motor nameplate does not indicate any connections whatsoever, not even where to land supply conductors.

Yes, I assume now that the nameplate image on the bottom left is to identify the windings themselves and their end label number(s) - and the nameplate image on the bottom right with the "Line" label is the actual intended connection to the supply voltage (for normal Run conditions).

 

[MTW]

Is this being started across the line or Wye Delta started? Curious minds would like to know.

 

[emiller233]

Is this being started across the line or Wye Delta started? Curious minds would like to know.

not sure to be honest.. they'll likely just use a DOL starter either way, like they always do...
(even if we tell them to use a wye/delta starter )

i just didn't want to hurt the motor...

it is in the shop just for system testing, wont be permanently installed

 

[MTW]

Then I would wire it up for the 480 low voltage connection as Jaref said and give it a go.

If they decide to add the Wye Delta afterwards, pay attention to the note on the second drawing.

Jaref would likely tell you to put it on a VFD, and call it done.

Connecting it temporarily for the hi voltage with low voltage supply, would do no harm for a test as long as it wasn't loaded.

 

[paulengr]

If it is going to run single speed anyway use a bypassed soft start. Far cheaper than VFD and you still get current and torque control in starting,

 

[kwired]

Is this being started across the line or Wye Delta started? Curious minds would like to know.

not sure to be honest.. they'll likely just use a DOL starter either way, like they always do...
(even if we tell them to use a wye/delta starter )

i just didn't want to hurt the motor...

it is in the shop just for system testing, wont be permanently installed

It is in that range where many POCO's will not want across the line starting. If you have a pretty large facility (load wise) and maybe even have your own branch at the transmission level, maybe you can start larger motors across the line than most customers in general typically can.

Here most the time if it is over 100HP they want other than across the line starting, which today is typically now using an electronic soft starter or VFD, but in past it could have been wye-delta, part winding starting or reduced voltage (with transformers) starting.

 

[winnie]

You say it is in the lab for testing prior to going into service.

Based on the nameplate diagram, you are probably fine connecting the motor in the low voltage delta configuration....but it is cheap and fast to connect in the high voltage delta connection first to test.

If the 'correct' connection is the high voltage delta but you use low voltage then you will see huge currents as the motor is driven hard into saturation. There is a good chance of breaking something. You would need to respond very quickly to shut the test down.

If the 'correct' connection is the low voltage delta but you use the high voltage connection then currents will be much lower than normal. You will see low locked rotor current at starting, sluggish acceleration, and once the motor gets up to speed you would have roughly half the expected no load current. All in all a much more benign way to be wrong.

Jon

 

[retirede]

You say it is in the lab for testing prior to going into service.

Based on the nameplate diagram, you are probably fine connecting the motor in the low voltage delta configuration....but it is cheap and fast to connect in the high voltage delta connection first to test.

If the 'correct' connection is the high voltage delta but you use low voltage then you will see huge currents as the motor is driven hard into saturation. There is a good chance of breaking something. You would need to respond very quickly to shut the test down.

If the 'correct' connection is the low voltage delta but you use the high voltage connection then currents will be much lower than normal. You will see low locked rotor current at starting, sluggish acceleration, and once the motor gets up to speed you would have roughly half the expected no load current. All in all a much more benign way to be wrong.

Jon

That’s what I was saying in post 18. But you did a much better job of it.