Need urgent help with Wye/Delta

[Alex Pel]

Finally it’s clear. The motor never reached a full speed and burnt to death.
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When a motor is started at reduced voltage, the current at the motor terminals is reduced in direct proportion to the voltage reduction while the torque is reduced by the square of the voltage reduction. If the "typical" NEMA B motor is started at 70% of line voltage, the starting current would be 70% of the full voltage value (that is, 0.70 x 600% = 420% FLA). The torque would then be (0.70)2 or 49% of the normal starting torque (that is, 0.49 x 150% = 74% Full Load Torque). Therefore, reduced voltage starting provides an effective means of reducing both inrush current and starting torque.
If the motor has a high inertia or if the motor rating is marginal for the applied load, reducing the starting torque may prevent the motor from reaching full speed before the thermal overloads trip. Applications that require high starting torque should be reviewed to determine if reduced voltage starting is suitable.
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[Lancie1]

Alex,

Apologize a lot, grovel some, talk about your starving kids that need braces on their teeth, then offer to have the motor rebuilt at your local Motor Rewinding Shop. It usually costs about half of a new one, or less.

 

[Alex Pel]

Thanks a lot Lancie1 and everybody.

Apologize a lot, grovel some, talk about your starving kids that need braces on their teeth, then offer to have the motor rebuilt at your local Motor Rewinding Shop. It usually costs about half of a new one, or less.

That is what I can only do.

 

[elevmike]

.... then offer to have the motor rebuilt at your local Motor Rewinding Shop. It usually costs about half of a new one, or less.

We used to have motors rewound, but for the most part in the last 10 years or so the cost seems to be about the same. As of late the only benifit to rewinding is because it's a special motor and turnaround time on rewinding might be far less then new.

Before jumping to rewind, get a quote on the rewinding and a quote for new. If its a standard motor (Frame, HP & RPM) getting a new motor might be both less expensive and more timely.

 

[Tark]

I would question who ordered the motor and who ordered the starter. Why would you pay for a Wye/Delta motor but not install a starter to run the motor as it was designed?