The main causes of three-phase current imbalance when the motor is running no-load

一、Power supply issue:
Unbalanced power supply voltage is one of the main causes of three-phase current imbalance. If the power supply voltage is unbalanced, the three-phase current will not be able to maintain balance during the operation of the motor.

二、Winding turn to turn short circuit:
When a winding of an electric motor experiences a turn to turn short circuit, the impedance of that phase decreases, causing an increase in the current of that phase, while the currents of the other two phases decrease accordingly, resulting in an imbalance of three-phase currents.

三、Starting equipment failure:
Starting equipment failure may also cause three-phase current imbalance during motor operation.

四、Incorrect coil wiring or incorrect coil turns:
In motors with rewinding, if there are errors in coil wiring or incorrect coil turns, it may also cause three-phase current imbalance.

五、Mechanical load problem:
Unbalanced mechanical load may also lead to three-phase current imbalance. For example, if the mechanical components of the electric motor (such as couplings, fan blades, etc.) are installed incorrectly or damaged, it may cause mechanical imbalance, which in turn affects current balance.

六、Internal problems of electric motors:
Internal problems of electric motors, such as poor insulation of windings, insulation and circuit issues of rotors, or loose or corroded wiring terminals, can all lead to three-phase current imbalance.

七、Environmental conditions:
Environmental conditions such as high temperature or humidity may affect the insulation performance and connection status of the motor, leading to current imbalance.

八、Control system issue: If the setting parameters of the motor controller (such as soft starter or frequency converter) are incorrect, it may also cause three-phase current imbalance

In response to the above reasons, corresponding measures can be taken to solve the problem of three-phase current imbalance. For example, checking and adjusting power supply voltage, repairing or replacing damaged windings, correcting wiring errors, ensuring mechanical load balancing, improving environmental conditions, and adjusting controller settings parameters.