Delta ASDA-B2 Servo Fault AL001 Over Current

Is your Delta ASDA-B2 servo drive showing AL001? Learn the top causes of over-current faults, from wiring errors to IGBT failure, and how to fix them step-by-step.

 

If you are working with the Delta ASDA-B2 series servo system and your production stops with AL001 flashing on the drive display, you are dealing with an Over Current fault. This is a critical protective alarm designed to prevent the internal power electronics from permanent destruction.

In this guide, we will break down exactly why this fault occurs and provide a systematic, technician-approved approach to getting your machine back into operation.

What is the AL001 Fault?

The AL001 alarm triggers when the drive detects a current spike that exceeds the safety threshold of the internal IGBT (Insulated Gate Bipolar Transistor). Essentially, the drive is sensing that it is pushing out more electricity than the motor or the wiring can safely handle.

Common Causes of AL001

• Output Short-Circuit: The most dangerous cause. This happens when the U, V, or W phases touch each other or the ground.
• Wiring Errors: The motor power cable is connected incorrectly or has a loose connection.
• IGBT Abnormality: The drive's internal "muscles" are damaged, often related to excessive heat sink temperatures.
• Parameter Mismatch: The control loop settings (gains) are too aggressive, causing the motor to vibrate or "hunt."
• Unreasonable Commands: Asking the servo to go from 0 to 3000 RPM too quickly (excessive acceleration).

Step-by-Step Troubleshooting Guide

1. Inspect the Physical Wiring

Before diving into the software, check the "copper." In 70% of cases, the issue is external to the drive.

• Check for Shorts: Inspect the motor power cable for nicks, cuts, or exposed conductors. Metal dust or shavings in the connector can also cause a phase-to-phase short.
• Verify the UVW Sequence: Ensure the drive terminals U, V, and W match the motor’s input terminals exactly as described in the user manual.
• The "Megger" Test: Disconnect the motor from the drive and check the insulation resistance of the motor windings. A grounded motor will trigger AL001 instantly.

2. Test for Hardware Failure (The Isolation Test)

To determine if the drive is internally damaged:

1. Turn off the power and disconnect the U, V, and W motor leads from the drive.
2. Power the drive back on and attempt to enable the "Servo ON" signal.
3. If AL001 still appears with no motor connected: The internal IGBT module is likely failed. You must send the drive back to a Delta distributor or a specialized repair center.

3. Adjust Acceleration and Motion Commands

If the drive only trips when the motor starts moving, your acceleration ramp may be too steep.

• Increase Acceleration Time: Soften the command. High-inertia loads require more time to reach speed without drawing massive current.
• Smooth the Command: Apply a position command filter (S-curve) to prevent jerky movements that cause current spikes.

4. Verify and Reset Control Parameters

Incorrect gain settings can cause high-frequency oscillations that look like over-current to the drive's sensors.

• The "Factory Reset" Method: If you suspect the parameters are "messed up," set the drive back to defaults (Parameter P2-08 set to 10).
• After resetting, re-enter the basic motor data and gradually adjust the tuning values.

Quick Reference Table: Remedy Summary

Symptom	Required Action
Exposed Conductors	Eliminate short-circuits and insulate wires.
Wiring Sequence Error	Rewire according to the User Manual diagrams.
Hardware/IGBT Failure	Contact Delta Support or send for professional repair.
Parameter Oscillation	Reset to factory defaults and perform Auto-tuning.
Steep Accel Command	Increase acceleration time or use a low-pass filter.

Pro-Tip: Heat Sink Maintenance

The Delta ASDA-B2 monitors the IGBT temperature. If the cooling fan is stopped or the heatsink is clogged with dust, the IGBT will act abnormally, leading to AL001. Ensure your cabinet is ventilated and the drive is clean of industrial grime.