How to Fix ABB ACS880 Fault 71A3 Mechanical Brake Closing Error

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Staring at Fault 71A3 on your ABB ACS880? Learn why your mechanical brake failed to close, how to check feedback switches, and which Group 44 parameters to adjust.

 

How to Fix ABB ACS880 Fault 71A3 Mechanical Brake Closing Error

Solving ABB ACS880 Fault 71A3: Mechanical Brake Closing Error

If you are working with an ABB ACS880—especially in a lifting or high-torque application—and you see Fault 71A3, the drive has detected a serious safety discrepancy.

This fault stands for Mechanical Brake Closing Failed. It means the drive sent a command to engage the mechanical brake, but it didn't receive the "I'm closed" confirmation signal it was expecting. Let's walk through why this happens and how to get your machine moving again safely.

What Exactly is Fault 71A3?

The ACS880 has a sophisticated Brake Control Logic (usually found in Parameter Group 44). When the drive stops, it tells the mechanical brake to close. If you have "Brake Feedback" enabled, the drive waits for a signal from a limit switch on the brake hardware. If that signal doesn't arrive within the time set in the parameters, the drive trips 71A3 to prevent the load from slipping.

Common Causes of 71A3

  • Faulty Brake Limit Switch: The physical switch on the brake is stuck, broken, or misaligned.
  • Wiring Issues: The feedback wire between the brake switch and the drive’s Digital Input (DI) is broken or loose.
  • Mechanical Delay: The brake is physically sluggish or slow to move due to wear or cold weather.
  • Parameter Timing: The "Brake Close Delay" is set shorter than the time the physical brake actually takes to move.
  • Relay Failure: The internal or external relay controlling the brake solenoid has failed.

Step-by-Step Troubleshooting Guide

1. The "Listen" Test

Stand near the motor (safely) and trigger a stop. Do you hear the mechanical "clack" of the brake engaging?

  • If you hear the brake move: The problem is likely the feedback switch or the wiring back to the drive.
  • If you don't hear anything: The drive isn't successfully telling the brake to close. Check the brake control relay and power supply.

2. Check Parameter Group 44

This is where the "brain" of the brake lives. Check these specific settings:

  • 44.07 (Brake acknowledge selection): This tells the drive which Digital Input is watching the brake. Ensure this matches your actual wiring.
  • 44.13 (Brake close delay): If your brake is mechanically old and slow, you might need to increase this time slightly to give the switch a chance to click before the drive faults.

3. Inspect the Physical Limit Switch

Mechanical brakes are often in dirty or vibrating environments. Check the limit switch on the brake itself:

  • Is it covered in grease or dust?
  • Is the lever arm bent or broken?
  • Use your multimeter to check if the switch actually closes/opens when you move it by hand.

4. Monitor Signal 44.01 (Brake Control Status)

Using the ACS880 keypad or Drive Composer software, look at Signal 44.01. This bit-coded signal tells you exactly what the drive thinks the brake is doing. It’s a great way to see if the drive is even "seeing" the feedback signal from your switch.

How to Reset Fault 71A3

  1. Fix the mechanical jam or wiring issue.
  2. Ensure the brake feedback switch is in the "Closed" position.
  3. Press Reset on the control panel.
  4. Important: If you are working on a hoist, ensure the load is securely supported before resetting, as the brake may release during your next start attempt.

Summary

The ABB ACS880 71A3 fault is a protector. It’s there to make sure you don't try to run a motor against a stuck brake, or worse, let a load drop because the brake isn't holding. Usually, a quick adjustment to the limit switch or a small tweak to the Brake Close Delay in Group 44 is all it takes to get back to work.

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