leitmotif
Member
We have mixer where two motor gearboxes drive two screw type mixer blades. Blades are six foot long 14" dia and are horizontal. When mixing they counter rotate to pump this liquid "slurry food stuff" around the bathtub shaped mixer. To empty one motor reverses and both now rotate in same direction. Boss wants to drive these with VFD and use one VFD for two identical motors - each 7.5 HP 480 3 phase.
I know we can use one VFD (15 HP or slightly larger) to drive both.
I also know we should not use relays on VFD output.
VFD can reverse two motors OK but not just one
OR is there a VFD that has dual outputs and is able to reverse just one?
The only other way is to put reversing contactors on VFD output for just one motor.
Sequence would be something like this
Operator shifts select switch from mix to empty.
VFD would have to come to a stop
VFD would then allow the reversing contactor to reverse only one motor and then restart both.
I personally would prefer to use two VFDs and drive each motor independently.
Anybody got any better ideas??
Dan Bentler
I know we can use one VFD (15 HP or slightly larger) to drive both.
I also know we should not use relays on VFD output.
VFD can reverse two motors OK but not just one
OR is there a VFD that has dual outputs and is able to reverse just one?
The only other way is to put reversing contactors on VFD output for just one motor.
Sequence would be something like this
Operator shifts select switch from mix to empty.
VFD would have to come to a stop
VFD would then allow the reversing contactor to reverse only one motor and then restart both.
I personally would prefer to use two VFDs and drive each motor independently.
Anybody got any better ideas??
Dan Bentler