No-load current is larger or smaller
● The reason for the large no-load current.
(1) The number of turns of the stator winding is less than the normal value.
(2) The air gap between the stator and the rotor is large.
(3) The core silicon steel sheet is of poor quality.
(4) The length of the core is insufficient or the stacking is not effective, resulting in insufficient effective length.
(5) Due to the excessive pressure during lamination, the insulation of the core silicon steel sheet is broken or the insulation performance of the original insulating layer is not satisfactory.
(6) There is an error in the winding wiring, and the number of parallel branches is more than the design value.
(7) A motor with a rated frequency of 60 Hz is supplied with 50 Hz AC.
(8) The power supply voltage is higher than the rated value. Near the rated voltage (especially above the rated voltage), the no-load current is proportional to the square of the voltage (even above the power of 3), so the increase in no-load current will be much greater than the increase in voltage.
● The reason for the small no-load current. The reason for the small no-load current is roughly opposite to the larger cause. The difference is that the magnitude of the current reduction will be less than the magnitude of the increase in no-load current for the above reasons.
Stall current three-phase unbalance imbalance
(1) The reason why the three-phase resistance of the same stator and the no-load current are unbalanced.
(2) The rotor has serious thin strips or broken strips.
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