star delta connection

[mobex]

Application:at a smoke exhausting sistem with an unknown (?)Kw motor the mesured current in star is 20A and in delta is 31A.At no load is 6.1A and 21A.Can I find out the motor power? and it would be ok if i'd use the motor just in the star connection?

 

[Skogsgurra]

The motor is obviously overexcitated when running in delta. (Current is more than three times higher).

You shall only use star connection for this motor. Better still; get the motor data or get a new motor.

Gunnar Englund

http://www.gke.org

 

[rbulsara]

Power=(sqrt 3)*V*I*(power factor)

Find or estimate the missing data and calculate.

How do you know that the voltage you are applying is correct?

If the motor speed is OK in star (with load), you may leave it in star.

 

[petronila]

Hello Mobex,

I think you can take frame and shaft speed readings and compare with standard three phase Frame charts, taking acount the no load and load currents (if the motor was powered with 440 Volts) this motor could be 15 HP (3600 or 1800 RPM) or 10 HP at 1200 RPM.
I Think too this Motor runs at star.

Regards

Petronila