Cause: Armature overvoltage comes when the voltage across the armature winding of the motor has exceeded its safe operating limit. This could be due to external factors or issues with the drive’s control. Overvoltage conditions can damage components, so it's essential to address the issue promptly.

F503 Armature Overvoltage fault in ABB DCS800 drive indicates that the voltage in the armature circuit has exceeded the drive’s programmed limits.

Here are steps to troubleshoot and resolve this fault:

1. Check the Incoming Power Supply:

• Verify the power supply feeding the drive. If the incoming voltage exceeds the drive’s specifications, it can cause the armature overvoltage fault.
• Ensure that the incoming supply is stable and within the drive’s rated voltage range.

2. Review the Drive Parameters:

• Armature voltage limit settings: Check the armature voltage limits in the drive’s configuration. If these are set too low, the drive may falsely trigger the overvoltage fault. Adjust the limits if necessary based on the motor’s rated voltage.
• Verify the field weakening point settings. Incorrect settings can lead to an overvoltage condition, especially during deceleration or high-speed operation.

3. Check Load Conditions:

• Sudden load changes can cause voltage spikes. Inspect the mechanical load connected to the motor for any rapid deceleration or changes in torque that could lead to an overvoltage condition.
• Ensure that any regenerative energy from the motor (such as during deceleration) is properly dissipated. If the motor is regenerating energy into the drive, it could cause the armature voltage to rise beyond acceptable levels.

5. Inspect the Armature Circuit:

• Ensure the armature wiring is properly connected and in good condition. Loose or damaged connections can lead to overvoltage faults.
• Measure the voltage directly at the motor terminals and compare it with the drive’s output to confirm that there are no anomalies.

6. Check for Motor Overspeed:

• If the motor is operating above its rated speed, it can generate excess voltage in the armature circuit. Ensure that the motor speed is within safe operating limits.
• Check feedback devices (such as encoders or tachometers) for proper operation. Faulty speed feedback can cause the drive to lose control of motor speed, leading to overspeed and overvoltage.