For a 50hp new motor, 65A rated current motor - No Load I=30A
In my old motor of same 50HP,65A, No load I=17A
What is the reason?
2007-11-12 16:35:50 · 4 answers · asked by bala m 1 in Science & Mathematics ➔ Engineering
The no load current is approximately the magnetizing current of the motor. It is also approximately the reactive portion of the current at any load. If these are 460 volt motors, the power factor of the old motor would be about 0.96 at full load and the pf of the new motor would be 0.89. It seems to me that the manufacturer may have changed the design to make the motor more efficient and reduced the power factor slightly in doing that. It may also be that the design has been changed to slightly change the voltage range for which the motor has its best performance. If the new motors have the proper current at full load and otherwise work well, the increased no load current should not be a problem.
2007-11-13 03:57:22 · answer #1 · answered by EE68PE 6 · 1⤊ 0⤋
I think the difference is in the winding resistances of the two motors. If you have a multimeter, measure the resistance of each winding of the two motors.
You'll find that the one with the higher currents has lower winding resistances.
2007-11-12 22:07:12 · answer #2 · answered by pmi 4 · 0⤊ 0⤋
Check your connections and the contacts. A loose or resistive connection will cause a voltage drop. The motor will draw additional current to compensate for the lower voltage.
2007-11-12 23:59:24 · answer #3 · answered by MarkG 7 · 0⤊ 1⤋
The new motor is designed to produce higher starting torque than the old one.
2007-11-13 04:51:15 · answer #4 · answered by Tim C 7 · 0⤊ 0⤋