Why Does Motor Speed Become Slower?

When the electric motor device is in use, sometimes people find that the speed is obviously slower than before, and it is relatively weak, which is very annoying. Then what is the main reason for this? How to solve it? Here we will introduce for you the main reasons and solutions for slower electric motor speed.

The possible reasons are as following

1. The one-phase winding of the wound rotor is open. At this time, the speed is only half of the rated speed. The three-phase winding of the rotor should be checked for open circuit or wrong wiring.

2. If the cage rotor bar is broken or de-soldered, the broken bar of the motor should be inspected and repaired.

3. The delta connection of motor stator windings is wrongly connected into a star shape, and the connection should be checked and corrected.

4. If the bearing is worn too much, it will cause the stator and rotor to rub, which is equivalent to an increase in load. If it is still running with full load, it will force the speed to drop. Repair the electric motor rotor and replace the bearings.

Mechanical aspects

1. Turn off the power and turn the electric motor shaft or pulley of rotor by hand to see if the rotation is flexible. If it is not flexible, remove the belt and check the electric motor bearing and gap between the stator and the rotor.

2. After removing the electric motor component, turn it flexibly by hand, and then test it under no load to see if the motor is still rotating slowly and easily generates heat.

If there is no problem with the above two steps, it means that the mechanical parts are good, and the circuit and power supply must be checked.

After these two inspection steps, if there is no problem with the mechanical parts of the motor, the circuit itself and the power cord must be checked.

Turn on the electric motor equipment and use a clamp-on ammeter to quickly measure whether the three-phase current is balanced. If there is a deviation, it cannot be too large. If the three phases are balanced, it means the motor is normal. If one phase is too high, it means there is a problem with this phase. If there is nothing, it may be a lack of phase. Use a multi-meter to check whether the power cord on the electric motor terminal can reach the rated voltage of the motor. Generally the rated voltage is 380V. In order to ensure the three-phase balance, you may further check whether the motor lacks phase.

The winding of the motor itself

1. Use a multi-meter to measure whether the resistance of the motor three-phase winding is balanced in the ohm range. If the difference is large, it indicates that this is abnormal.

2. Use a multi-meter to check the ohm range of the three windings of the motor to see if all three windings are connected and there is no connection lost.