Cause : UNDERVOLTAGE comes when the voltage supplied to the internal DC bus of the drive is lower than the minimum required for normal operation.

The A2003 alarm on an ABB ACS355 drive indicates a DC undervoltage condition. This means that the DC bus voltage has dropped below the minimum threshold required for proper drive operation.

Here are steps to troubleshoot and resolve this issue:

1. Check Power Supply

• Voltage Levels: Verify that the AC input voltage to the drive is within the specified range. Inadequate supply voltage can cause the DC bus to drop.
• Power Quality: Ensure there are no significant voltage sags, dips, or interruptions in the power supply.

2. Inspect Connections

• Power Connections: Check all power connections to ensure they are secure and correctly wired. Loose or corroded connections can lead to voltage drops.
• Grounding: Verify that the drive is properly grounded. Poor grounding can cause various electrical issues, including undervoltage.

3. Check for Overloads

• Load Issues: Ensure that the motor is not experiencing sudden overloads or mechanical binding, which can cause a significant voltage drop.
• Deceleration Settings: Rapid deceleration can cause the DC bus voltage to drop if the braking resistor is not sized correctly. Check and adjust the deceleration time (Parameter 2205) if necessary.

4. Inspect the Drive’s Internal Components

• DC Bus Capacitors: Faulty or aged capacitors can cause DC bus voltage issues. If the drive is older, the capacitors may need to be inspected or replaced.
• Internal Wiring and Components: Check for any signs of damage or wear in the drive’s internal components.

5. Parameter Settings

• Minimum DC Voltage Level: Ensure that the minimum DC bus voltage level parameter is set correctly for your application. This parameter can be found in the drive’s settings and might need adjustment based on the specific requirements.