Brake sequence fault

What does E.MB7 mean?

This brake sequence fault stops the inverter output due to a sequence error occurring during the operation of the brake sequence function (configured by Pr. 278 to Pr. 283). This protective feature is not active in the initial inverter status. It indicates a timing or logical error in the controlled braking process.

• Timing violation during the brake release or engagement phase, where the motor speed or brake feedback state doesn't transition as expected by Pr. 278-Pr. 283.
• Insufficient holding torque from the brake, allowing the motor to drift or rotate while the brake is commanded engaged.
• Intermittent wiring fault or loose connection in the brake feedback circuit, leading to temporary signal loss or erratic readings.
• Incompatible brake type or characteristics (e.g., response time, torque) for the application, not allowing the configured sequence parameters to be met.
• Digital input assigned to brake feedback (e.g., STO1, STO2 terminal) being stuck ON or OFF due to internal inverter fault or external wiring issue.

Click steps to track your progress.

1. 1

   1. Cross-reference the mechanical brake's specified response times for engagement and disengagement with the inverter parameters Pr. 278 (Brake opening command time) and Pr. 279 (Brake closing command time). Adjust if discrepancies are found.

2. 2

   2. Perform a static brake test: energize the brake, attempt to rotate the motor shaft by hand (if safe and possible), and observe for any slippage, then verify the brake feedback switch state.

3. 3

   3. Inspect all connections from the inverter's brake control output and brake feedback input terminals (e.g., R-A/R-C for control, DI3 for feedback) to the brake assembly for tightness and corrosion.

4. 4

   4. Measure the resistance of the brake coil (if DC brake) or check continuity (if AC brake) at the brake terminal block with power removed to ensure the coil is intact and not shorted or open.

5. 5

   5. Monitor the brake feedback input signal (e.g., DI4 status) on the inverter's display while manually activating and deactivating the brake to confirm reliable signal transition without chatter.