Preliminary investigation plan:
1. Measure whether the three phases of the motor are balanced properly.
2. Check if the fan blades rotate smoothly after turning the motor.
3. What are the parameters for motor overload protection? The standard motor overload protection current is set at 1.1 times the rated current of the motor. If the current is set too high, it indicates that the motor may continue to be overloaded.

Confirmed after investigation:
The pump rotation jamming indicates that the pump itself is abnormal,
1. Motor bearing damage → Check whether the rotation is smooth by dialing the rear fan blade, remove the three bolts connecting the pump head and bracket, exit the motor, and then dial the rear fan blade separately to confirm.
2. The internal abnormality of the pump head → if the entire pump rotates smoothly but the motor rotates normally, it can be inferred that the pump head is abnormal and needs to be disassembled for inspection.
3. Motor winding fault → After the pump is stopped, measure the three-phase winding of the motor with a multimeter to confirm if it is balanced and normal. The main cause of the abnormality is due to excessive motor load or abnormal power supply connection, which requires in-depth investigation.

The pump rotates normally and the winding is normal:
Check if the three-phase voltage of the connected power supply is normal and if there are any abnormalities in the contactor.
Check if the pipeline is blocked.