During the operation of the motor slot paper machine, there is a noticeable slowdown in speed compared to before. What could be the primary cause of this? Let's analyze it briefly for everyone!

Section 1: Machinery Aspect

Shut off the power and manually rotate the shaft or belt wheel of the rotor to check for smooth rotation. If it's not smooth, remove the belt, inspect the bearing in the motor slot of the paper machine, and the gap between the stator and rotor.

2. After removing the slot paper machine, we manually rotated it with agility, and then tested it under no load to check if the motor was still rotating slowly and prone to overheating.

If there are no issues with the aforementioned two steps, it indicates that the mechanical components are in good condition, and it's time to inspect the circuitry and power supply.

After these two inspection steps, if no issues are found with the mechanical components of the motor, then the circuit itself and the power lines need to be checked.

Open the slot paper machine and use a clamp-on ammeter to quickly measure whether the three-phase current is balanced. If there is a deviation, it should not be too great. If the three phases are balanced, it indicates normal operation.

If one phase is too high, it indicates an issue with that phase; if nothing is present, it may suggest a missing phase. Use a multimeter to check if the power lines at the motor slot paper machine terminal can reach the rated voltage, typically 380V, to ensure balanced three-phase power, and further determine if a phase is missing.

Section II: Motor Winding

1. Check the ohm range of the three windings with a multimeter to ensure all three windings are connected and there are no connections lost.

2. Measure the resistance of the three-phase winding using a multimeter within the ohm range to ensure it is balanced. Significant discrepancies indicate an abnormal condition.