Mechanical brake opening not allowed

What does 71A5 mean?

The conditions required for opening the mechanical brake cannot be met, often because the brake is being intentionally kept closed by a parameter setting (e.g., 44.11 Keep brake closed) or due to a safety interlock. This prevents motor operation and is usually a configuration or interlock issue.

• Parameter P44-11 (Keep brake closed) is set to 'Always' or 'When stopped', preventing automatic opening.
• The drive is in a safety state (e.g., STO active) or protective stop that inhibits brake opening.
• Motor speed (Parameter P01-01) is not zero or below the defined brake release threshold (Parameter P20-03).
• An external command (e.g., PLC signal via digital input P04-01) is actively holding the brake closed.
• Internal drive logic or state machine prevents brake opening due to unfulfilled safety or operational conditions.

Click steps to track your progress.

1. 1

   Check parameter P44-11 (Keep brake closed) setting and ensure it is configured to allow opening as required by the application.

2. 2

   Verify that no safety function (e.g., STO, Safe Stop 1) is active or preventing drive operation by checking relevant status bits (e.g., P01-14).

3. 3

   Monitor actual motor speed (Parameter P01-01) and ensure it is below the brake release speed threshold (Parameter P20-03) before attempting to open.

4. 4

   Check the status of digital inputs (e.g., P04-01 to P04-06) to ensure no external command is holding the brake closed.

5. 5

   Review the drive's control logic (e.g., using Drive composer's logic viewer) to identify specific conditions preventing brake opening.