The difference of VFD Two-wire control&Three-wire control

VFD can be started and stopped by Two-wire control&Three-wire control model. What is the difference between Two-wire control&Three-wire control?

1. Different principles

Two-wire control mode uses switch to control.Switch to open, the inverter run; Turn to close, the inverter stop.

Three-wire control mode uses buttons to control.The principle of the three-wire system is similar to the self-locking circuit of the AC contactor, with one starting point and one stopping point. The stopping point must be closed when starting. If the stopping point is disconnected, the inverter cannot be started.

2. Different wiring

Two-wire control wiring；

Three-wire control wiring:

3. Different usage

Bigger power inverter usually uses three-wire control model.

Two-wire control model is used for smaller power inverter.

4. Different signal

The two-wire control mode is a signal for the forward or reverse direction with the operation signal.  The three-wire control mode means that the operation signal is separate and the other two signals of the operation signal are required to work. Three-wires are what is commonly called pulse signals.