AL001 Over Current Fault in Delta ASDA-B2 Servo Drive

AL001 Over Current in the Delta ASDA-B2 Servo Drive indicates that the servo drive has detected output current exceeding its allowable protection limit. The drive continuously monitors the motor current to protect the IGBT power module and servo motor. If excessive current is detected due to a short circuit, incorrect wiring, improper parameter settings, or rapid acceleration, the drive generates Alarm AL001 and immediately disables the output to prevent damage.

This fault generally indicates a problem with the motor, motor wiring, drive parameter settings, command profile, or inverter output stage, rather than the incoming power supply.

Possible Causes

• Drive output short-circuited.
• Phase-to-phase short circuit in the motor cable.
• Motor wiring error.
• Incorrect U, V, W motor connections.
• Exposed or damaged motor cable conductors.
• Ground fault in the motor or cable.
• Abnormal IGBT module.
• Heatsink temperature abnormal.
• Internal inverter hardware failure.
• Incorrect control parameter settings.
• Incorrect servo tuning parameters.
• Acceleration time set too short.
• Excessive acceleration or deceleration command.
• Sudden load changes causing excessive current.
• Mechanical overload or locked motor shaft.

Solutions

• Eliminate any short circuit in the motor or output wiring.
• Ensure no exposed conductors are touching each other or ground.
• Rewire the motor according to the Delta user manual.
• Verify correct U, V, and W motor phase connections.
• Inspect the motor cable for insulation damage.
• Check for phase-to-ground faults.
• Restore control parameters to their default values if incorrect settings are suspected.
• Gradually readjust parameters after restoring defaults.
• Increase the acceleration time to reduce peak current.
• Apply a command filter or use smoother motion profiles.
• Inspect the heatsink for overheating and verify cooling.
• If the IGBT module is faulty, return the drive to an authorized Delta distributor or service center for repair or replacement.

Additional Information

The Delta ASDA-B2 Servo Drive continuously monitors the output current delivered to the servo motor.

Alarm AL001 is generated when the measured output current exceeds the drive's protection threshold.

According to Delta, common causes include:

• Output short circuit.
• Incorrect motor wiring.
• Abnormal IGBT or heatsink temperature.
• Incorrect control parameter settings.
• Excessively fast acceleration commands.

Unlike an Overload Alarm, which is based on thermal calculations over time, AL001 Over Current is triggered by an instantaneous or rapidly rising current that could damage the drive's power electronics.

If the alarm occurs repeatedly after wiring and parameter corrections, the inverter output stage may be damaged and require professional service.

Common Symptoms

• Servo drive displays AL001 Over Current.
• Servo motor stops immediately.
• Alarm occurs at startup.
• Alarm appears during rapid acceleration.
• Servo motor vibrates or jerks.
• Motor fails to rotate.
• Drive trips repeatedly after reset.
• High motor current is observed.
• Heatsink temperature may be abnormally high.
• Servo output is disabled until the alarm is cleared.

Recommended Troubleshooting Sequence

1. Disconnect power and follow lockout/tagout procedures.
2. Inspect the motor cable for short circuits or insulation damage.
3. Verify correct U, V, and W motor wiring.
4. Check for phase-to-phase and phase-to-ground faults.
5. Ensure no conductors are exposed.
6. Inspect the motor for mechanical binding or overload.
7. Verify the servo parameter settings.
8. Restore parameters to factory defaults if necessary.
9. Increase the acceleration time or smooth the command profile.
10. Inspect the heatsink and cooling system.
11. Check for signs of IGBT damage.
12. Restart the servo drive.
13. Confirm that the alarm has cleared.
14. Test the servo under normal operating conditions.
15. Contact an authorized Delta service center if the alarm persists.

AL001 Over Current Check Table

Check Point	Action
Motor cable	Inspect for short circuits and insulation damage
Motor wiring	Verify correct U, V, W phase connections
Output short circuit	Remove any phase-to-phase or phase-to-ground fault
Exposed conductors	Repair or replace damaged wiring
Parameter settings	Restore defaults and retune if required
Acceleration time	Increase to reduce peak current
Motion command	Apply smoother acceleration or command filtering
Heatsink	Check for overheating and proper cooling
IGBT module	Inspect for hardware failure
Delta service center	Contact if the alarm remains after inspection

Preventive Maintenance Tips

• Regularly inspect motor power cables for insulation damage.
• Verify motor wiring after installation or maintenance.
• Keep the servo drive cooling system clean and unobstructed.
• Avoid excessively aggressive acceleration and deceleration settings.
• Tune servo parameters according to the application requirements.
• Protect cables from mechanical damage and vibration.
• Periodically inspect power terminals and tighten as required.
• Monitor motor current during operation to identify abnormal trends.
• Ensure the servo drive is correctly sized for the motor and application.
• Record recurring AL001 Over Current alarms to assist long-term diagnostics.

Proper inspection of the motor, motor wiring, output cables, control parameter settings, acceleration profile, heatsink, and IGBT power module, together with routine preventive maintenance and correct servo tuning, will help prevent recurring AL001 Over Current alarms in Delta ASDA-B2 servo drives, ensuring reliable servo operation, effective protection of the power electronics, and dependable long-term performance of the servo system.