Delta/"Y"

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ashtrak

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Maryland
I friend called me and asked if I was still logging into that "electrical website".
Seems he bought a motor off e-bay, if I have the story right. The motor is three phase 240. The service is 240 3 phase Delta. He said there was no name plate so he looked it up in his ugly's. For some reason he chose to hook it up delta confiquration. He said it drew excessive amps.He hooked it up "Y" and it was ok. I think that was the correct story. Anyway any thoughts.

Thanks
 
I believe, most small general purpose motors in the US have their windings connected in a wye configuration.
 
If it is a small motor, it is probably a 9-lead motor, which, if it is delta internally, connot be connected wye, and if it is wye internally, cannot be connected delta. We need more info on the motor.
 
Such is one of the problems of buying motors off of Flea-Bay, especially if you are not a motor expert.

And just for the record, the Y or Delta when discussing 3 phase motors has NOTHING to do with the supply voltage. As far as that goes, you are only using 3 wires. How it is connected at the transformer is irrelevant.

Sounds like maybe it is an IEC motor. IEC dual-voltage motors are wound such that if the windings are connected in Delta, they are to be used on the lower voltage, and in Y they are to be used on on the higher voltage. For them, a Dual Voltage motor means 380 / 220V because their systems are 380Y220 (or now 415Y240). So if he connected an IEC designed motor to 220V, but connected it in the Delta pattern, he is applying only 58% of the required voltage to the motor. It will deliver only 33% of the rated torque. So when loaded, it will usually stall, meaning it will go into Locked Rotor condition. Locked Rotor current is usually 600% of the motor FLA, but when mis-connected, the LRC will also be reduced by the same ratio, or 33%. 33% of 600% is 200%, the condition your friend saw.

So he SHOULD be connecting it in Delta, not Wye if it is an IEC motor. BUT, if it is an IEC motor, the Ugly's connection chart for NEMA motors would not apply, so he may not have been connecting it in Delta as he thought it was.

First determine exactly what kind of motor he has, then use this chart for connections.
http://www.patchn.com/ connection charts
 
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Thanks

Thanks

Thanks for the replys: Icalled him this morning and gave him the info. He said he had called the manufacturer and they sent him a wye configuration to use, and that the motor was running fine. He also said the config was the same as in Uglys.I'm not familier with the term IEC and he wasn't either and I havn't had a chance to do any reading yet.I wish I had been exposed more to motor hookups in my work envirnment. And yes it is a nine lead motor.
 
Jraef said:
Such is one of the problems of buying motors off of Flea-Bay, especially if you are not a motor expert.

And just for the record, the Y or Delta when discussing 3 phase motors has NOTHING to do with the supply voltage. As far as that goes, you are only using 3 wires. How it is connected at the transformer is irrelevant.

Sounds like maybe it is an IEC motor. IEC dual-voltage motors are wound such that if the windings are connected in Delta, they are to be used on the lower voltage, and in Y they are to be used on on the higher voltage. For them, a Dual Voltage motor means 380 / 220V because their systems are 380Y220 (or now 415Y240). So if he connected an IEC designed motor to 220V, but connected it in the Delta pattern, he is applying only 58% of the required voltage to the motor. It will deliver only 33% of the rated torque. So when loaded, it will usually stall, meaning it will go into Locked Rotor condition. Locked Rotor current is usually 600% of the motor FLA, but when mis-connected, the LRC will also be reduced by the same ratio, or 33%. 33% of 600% is 200%, the condition your friend saw.

So he SHOULD be connecting it in Delta, not Wye if it is an IEC motor. BUT, if it is an IEC motor, the Ugly's connection chart for NEMA motors would not apply, so he may not have been connecting it in Delta as he thought it was.

First determine exactly what kind of motor he has, then use this chart for connections.
http://www.patchn.com/ connection charts
Click to expand...
Excellent chart - thanks for the link
 
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