Frequency drive (VFD)
Forward - Reverse Operation
What is forward-reverse operation with a frequency drive?
It is a connection in which a motor runs forward or reverse with a frequency drive. Separate digital inputs are used for forward and reverse; when the emergency stop on the common line is pressed, both directions are cut.
Where is it used?
It is used on conveyors, doors, hoists and two-way machines instead of a contactor forward-reverse circuit. The change of direction is smooth, with no contactor wear and no risk of short circuit.
Wiring and parameters
The forward and reverse buttons go to two digital inputs and the inputs' functions are assigned with parameters. If both inputs are active the drive does not run. A three-position (forward-0-reverse) selector switch can be used instead of maintained buttons.
What to watch out for
Depending on the machine's safety requirements, the emergency stop is designed to cut not only the drive input but, if needed, the drive's power or its safe torque off input as well.
Parts used
- Motor 3~
- M1
Run it in the simulator.
This circuit is ready in the CoilPath library. Open it, press the buttons and follow the current. It also comes with a wiring view and a panel layout.