Cause : Locked rotor comes when a motor is prevented from turning despite being supplied with electrical power. This can happen due to various reasons, including mechanical obstructions, excessive load, or electrical faults.

Here's how you can address a locked rotor condition:

1. Safety First: Before attempting any troubleshooting, ensure the power to the motor is switched off and properly locked out to prevent accidental startup.

2. Check Mechanical Obstructions: Inspect the motor and connected machinery for any mechanical obstructions that could prevent rotation. This could include debris, jammed parts, or misalignment. Remove any obstructions found.

3. Assess Load Conditions: Evaluate the load connected to the motor. If the load is excessive or beyond the motor's capacity, it can lead to a locked rotor condition. Reduce the load if possible or redistribute it to alleviate the strain on the motor.

4. Check Motor Windings: Inspect the motor windings for any signs of damage, such as burnt insulation or melted wires. A short circuit or ground fault in the motor windings can cause the motor to lock up. Repair or replace damaged windings as needed.

5. Test Capacitors (if applicable): If the motor uses capacitors for starting or running, test them for proper functionality. Faulty capacitors can lead to starting issues or cause the motor to lock up. Replace any defective capacitors.

6. Verify Power Supply: Ensure the motor is receiving the correct voltage and frequency as per its specifications. Fluctuations or imbalances in the power supply can affect motor performance and lead to locking rotor conditions.

7. Inspect Bearings and Lubrication: Check the motor bearings for wear or lack of lubrication. Worn bearings can cause excessive friction, hindering motor rotation. Lubricate or replace bearings as necessary.