VFD with multiple fan motors overcurrent protection
VFD with multiple fan motors overcurrent protection
(OP)
I know the the overcurrent protection line side needs to be fast interrupt. What is the concensus for overcurrent on the load side with multiple fan motors.
Any concerns for multiple motors on single drive
Any help appreciated.
Any concerns for multiple motors on single drive
Any help appreciated.





RE: VFD with multiple fan motors overcurrent protection
RE: VFD with multiple fan motors overcurrent protection
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: VFD with multiple fan motors overcurrent protection
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AD4014 Application Data Multiple Motor Operation
RE: VFD with multiple fan motors overcurrent protection
RE: VFD with multiple fan motors overcurrent protection
I would suggest that you choose OL relays so that the motor FLC is roughly in the middle of the adjustment range. There will be losses in the cables associated with the VFD PWM frequency and you may need to adjust the 'overload' protection for a little over the motor FLC to allow for that.
Please be aware that 'Instantaneous Overcurrent' - short circuits between phases or phase to earth - will not be protected against. The VFD will be much quicker at tripping (or at least should be!) than the relay opening when this kind of fault occurs. I believe it will be very dificult to find a relay that will trip on Instantaneous before the drive trips.
So this will mean that if one of your multiple motors or their cables has a short circuit fault then the drive will trip and all the motors will stop. Normally, this is rare! It will depend on your application.
Drivesrock.
RE: VFD with multiple fan motors overcurrent protection
Eng-Tips: Help for your job, not for your homework Read FAQ731-376