3 phase motor wiring questions

roll-a-leblond · Jul 16, 2020

Hey gang,I have a cincy 9" column 4' arm radial drill I'm putting a vfd on. I have a twin drill I set up with one a couple months ago, no problems.

This one however only has 3 wires coming out of the motor instead of the usual 9 for 3 phase. I think it was set up for 440v,I went in there to rewire it for 220v and saw only 3 wires. How do I check to see what voltage its wires up for?

DaveKamp · Jul 16, 2020

Uhhh...

roll-a-leblond said:
Hey gang,I have a cincy 9" column 4' arm radial drill I'm putting a vfd on. I have a twin drill I set up with one a couple months ago, no problems.

This one however only has 3 wires coming out of the motor instead of the usual 9 for 3 phase. I think it was set up for 440v,I went in there to rewire it for 220v and saw only 3 wires. How do I check to see what voltage its wires up for?

Welll... if there's only three wires in the MOTOR's connection box, then you likely have only a single voltage 480 motor...

Are you double-dawg CERTAIN there's no other wires anywhere else?

roll-a-leblond · Jul 16, 2020

Yes I'm certain, only 3 coming out,how would you test to see what voltage it is wired.

The name plate says 220-440 but there are scratches over the motor lead wiring diagram. It's a 254 frame Westinghouse ,1160 rpm at 50 hz,3hp.

Is it costly to rewire,or a new motor the best option.

johnoder · Jul 16, 2020

Name plate says it. Good chance other wires were kept inside (for its last application) but may be there for the taking by a motor shop

Be interesting to hear if the three still have their "T" number tags - should be numbered T1, T2 and T3. If still inside, there would be 3 bundles of two, and they would be numbered 4 & 7, 5 & 8 and 6 & 9

If you get to where you have the nine, the bundles look like this for 240v

1 & 7 bundled with Line 1; 2 & 8 bundled with Line 2; 3 & 9 bundled with Line 3; 4, 5 & 6 bundled with each other but nothing else

Phil in Montana · Jul 16, 2020

Been rewound, to voltage the shop was using, could be 480 or 240 feed it 240 and see what it draws for amps...Phil

roll-a-leblond · Jul 16, 2020

Wont it be weak on 240 if wired for 480 mr Phil?

Mr john I can look into the frame and still only see 3 leads,no numbers left on the 3 coming out.

SAF · Jul 16, 2020

Look at the existing motor starter for a clue, If it has one. What is the coil voltage? What are the heater sizes? Does it have a control transformer?

Many motor rewind shops will only bring out 3 leads, unless you specify to keep it dual voltage. Its easier for them to splice it that way. Opening it up and re-splicing and tying the leads down and re-varnishing can cost near the price of a rewind.

SAF Ω

Phil in Montana · Jul 16, 2020

Yes only 25% hp, the amps will let you know. If it is 480 you can not get full hp on 240 volt but you will be able to tell what it is wired for.. the only other way to tell what voltage is take the motor apart and see where the jumpers are...Phil

Jraef · Jul 23, 2020

roll-a-leblond said:
...
The name plate says 220-440 but there are scratches over the motor lead wiring diagram. It's a 254 frame Westinghouse ,1160 rpm at 50 hz,3hp. ...

50Hz... that means it's either built as a Brazilian motor (they use 440V 50Hz), or it was meant as a European motor for 220/380V 50Hz, which would work fine for 460V 60Hz, but NOT for 230V 60Hz because the V/Hz ratio would be wrong, so the rewind shop just eliminated your ability to reconnect it that way since it would damage the motor.

Phil in Montana · Jul 23, 2020

1160rpm would be 60hz, 965 rpm would be 50 hz. And its moot anyway a 50hz works just fine on 60hz and its going to be feed by a vfd.....Phil

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3 phase motor wiring questions

roll-a-leblond

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DaveKamp

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roll-a-leblond

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johnoder

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Phil in Montana

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roll-a-leblond

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SAF

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Phil in Montana

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Jraef

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Phil in Montana

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