Application Notes: Power Off VFD Function
If the main power is lost to a VFD while the motor is under load, the DC bus of the VFD drops at an accelerated rate compared to no load conditions. When the DC bus reaches a low level, the VFD would shut down, disabling the output modulation and releasing the motor to coast to a stop. The motor coasting to a stop under the loss of main input power may not be of concern for many VFD applications.