To prevent load drift (creep) on a VFD-controlled hoist, the brake must set only when the motor is truly producing zero speed and sufficient holding torque is not needed from the drive. Typically, the VFD performs controlled deceleration to near zero, maintains a small holding torque to stabilize the load, then commands the brake to engage. After brake confirmation (via a switch or timing), the drive torque can drop to zero.
If the brake sets too late, the load may drift or lower slightly before the brake clamps. If it sets too early—while the motor still has speed or torque transitions—shock loads, jerky motion, and increased lining wear can occur.
Use feedback where possible: speed feedback (encoder) and brake status feedback (limit switch) improve consistency. Adjust deceleration ramps, torque proving, and brake delay times during commissioning under representative loads. For safety, ensure the brake is fail-safe and capable of holding the load independent of the VFD. Good brake-VFD coordination is essential for smooth starts, accurate positioning, and compliance.