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ErrorLib — Industrial Fault Code Library

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73B0

Emergency ramp failed

ABB · ACS880

What does 73B0 mean?

The motor has not stopped within the maximum allowed time after an emergency stop command (Off1 or Off3 mode) was issued. This indicates a failure in the emergency braking sequence, which could lead to unsafe operation if the system cannot stop as expected. The drive trips and coasts to a stop.

Common Causes

  • Mechanical binding or excessive load on the motor shaft preventing it from decelerating within the programmed time.
  • Motor brake not engaging or failing to provide sufficient torque to stop the motor quickly (e.g., brake pads worn, spring fatigued).
  • Deceleration time parameter (e.g., P2-11 'Deceleration time 1') is set too long for the required emergency stop duration.
  • Motor current or torque limits (e.g., P1-54 'Motor current limit') are set too low, preventing sufficient braking torque during deceleration.
  • Failure of the drive's internal braking chopper or external braking resistor (if installed) to dissipate regenerative energy.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    1. Disconnect the motor from the mechanical load and manually attempt to rotate the shaft to check for binding or excessive friction.

  2. 2

    2. Verify the motor brake functionality by applying a separate 24VDC (or appropriate voltage) to the brake coils and observing full engagement.

  3. 3

    3. Reduce the deceleration time parameter (e.g., P2-11) by 10-20% increments and re-test the emergency ramp function, ensuring the mechanical system can handle it.

  4. 4

    4. Monitor the motor's actual braking current during an emergency stop attempt using parameter P1-02 to ensure it reaches sufficient levels.

  5. 5

    5. Inspect the braking resistor for damage or overheating and measure its resistance value to confirm it is within specified limits.

Browse all codes in this manual (116)
Verified technical data. Last updated: April 2026

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Source: ABB ACS880
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