What is the reason for the large no-load loss of the motor

Update:01-11-2019
Summary:

Under normal circumstances, the ratio of no-load loss t […]

Under normal circumstances, the ratio of no-load loss to rated power is calculated as a percentage, generally in the range of 3%-10%. For motors of the same specification, the fluctuation range of the no-load motor is 5%-15%, and the fluctuation range of no-load loss At 5%-20%, no-load current and no-load loss will affect the power factor of the motor. It is very important to check the no-load data control of the motor during the test.
The reason for the large no-load loss of the Tektronix motor is:
(1) The motor is poorly assembled and the mechanical loss is increased;
(2) The bearing rotation is not flexible, or the bearing and the shaft and the end cover are not properly selected;
(3) The bearing grease is too much filled, causing the motor to be blocked;
(4) The iron loss increases due to the uneven repair of the iron core (generally between 10-30%);
(5) Repairing the inner bore of the stator, the iron loss has a great influence, generally 20-40%;
(6) The fan is not suitable (larger than the design or defective);
(7) The winding coil turns or pitch is small;
(8) Poor iron core insulation treatment and iron core aging;
(9) There is a burr on the punching piece, which causes the chip to be short-circuited when the burr is broken.
The actual test process found that for motors using sealed bearings, the mechanical loss of the motor using the contact bearing is larger than that of the motor using the non-joint bearing, which ultimately has a significant effect on the efficiency of the motor, especially for high-efficiency motors, which may lead to efficiency performance. The indicator has a qualitative change.