Brake Check Fault

What does 28 mean?

An issue was detected during the drive's internal mechanical brake check routine. This can indicate a problem with the mechanical brake itself, its control circuitry, or the drive's monitoring, potentially leading to unsafe operation or motor movement when stopped.

• Mechanical brake pads worn beyond safe operating tolerance or seizing due to contamination.
• Brake control circuit malfunction, such as a failed brake solenoid coil (open or short circuit) or a faulty brake relay.
• Brake feedback switch (e.g., limit switch or proximity sensor) stuck, misaligned, or having an intermittent wiring fault.
• Drive parameter P12-23 (Brake release delay) or P12-24 (Brake engage delay) configured incorrectly for the specific motor and brake assembly.
• Insufficient brake torque (e.g., Parameter P12-21, Brake torque) set below the required holding torque for the application.

Click steps to track your progress.

1. 1

   1. De-energize the drive and test the continuity of the brake solenoid coil at its terminals (e.g., X1-1, X1-2), comparing the measured resistance to the manufacturer's specification.

2. 2

   2. Visually inspect the mechanical brake assembly for wear, damage, or obstructions that prevent free movement; manually actuate the brake (if safe) to observe its operation.

3. 3

   3. Verify the operation of the brake feedback switch by checking continuity across its contacts in both engaged and disengaged states, ensuring proper mechanical activation.

4. 4

   4. Review and adjust drive parameters P12-23 (Brake release delay) and P12-24 (Brake engage delay) to match the specifications of the motor and brake unit.

5. 5

   5. Measure the output voltage at the drive's brake control terminals (e.g., U, V, W for AC brake, or dedicated DC output) when the brake is commanded to release (e.g., 230VAC).