High Slip Braking Overload

What does oL7 mean?

This fault occurs when the load inertia is too large, an external force rotates the motor during deceleration, or something prevents proper deceleration on the load side. The output frequency remains constant longer than the n3-04 [HSB Overload Time] setting. This indicates that the drive's high slip braking mechanism is being overstressed, potentially leading to drive or motor damage if unresolved.

• High inertia load (e.g., large flywheel, heavy conveyor) exceeding the drive's braking capacity without an external braking resistor.
• External force (e.g., gravity on a vertical load, regenerative fan) driving the motor during deceleration.
• Deceleration time (C1-02) set too short for the load inertia, leading to excessive regenerative energy.
• Failure of an external braking resistor or its associated chopper circuit.
• Motor's rated slip or magnetizing current parameters (e.g., P1-03, P1-07) are inaccurately configured, affecting motor model.

Click steps to track your progress.

1. 1

   1. Increase deceleration time parameter C1-02 to a longer duration to allow for slower energy dissipation.

2. 2

   2. Verify the presence and functionality of an external braking resistor; measure its resistance (e.g., with ohmmeter) and check connections (e.g., B1, B2 terminals).

3. 3

   3. Check parameter R1-01 (Braking Resistor Ohms) matches the installed resistor's value.

4. 4

   4. Implement an external mechanical brake or counterweight if the load is primarily vertical or subject to external driving forces.

5. 5

   5. Monitor the drive's DC bus voltage (e.g., U1-08) during deceleration to observe if it rapidly rises above the overvoltage trip point.

6. 6

   6. Review the application for excessive load inertia; consider mechanical changes or a larger drive/braking solution if necessary.