Difference between Single Phase VFD and Three Phase VFD

Variable frequency drive that we often talk about generally refers to the low-voltage VFD, and low-voltage VFD can be divided into single phase VFD and three phase VFD from the perspective of power supply voltage.

The biggest difference between single phase VFD and three phase VFD is that power supply of single phase VFD is consisted of a live wire and a neutral wire with a voltage of 220V. There’s only one live wire, so it’s called single phase. Power supply of the three phase VFD has three live wires, so it’s called three phase VFD, as well as three phase power input VFD.

In addition, output voltage of the single phase VFD can be divided into single phase output and three phase output. The three phase output here would not exceed the power supply voltage. If the single phase input is 220V, the three phase output would also be 220V, which is different from the output of three phase VFD. Correspondingly, connection modes of their motors are also different. If the connection doesn’t match with the voltage, the motor has no power.

Single phase input means that there are only two lines for power supply input (one neutral line and one live line), the phase voltage of input voltage is 220V. Three phase input means that there are three input wires (three-phase three-wire) or four input wires (three-phase four-wire), generally, the three-phase four-wire is common. Three input live wires and one neutral wire, the phase voltage between each live wire and neutral wire is 220V, the phase voltage between every two live wires is 380V.

When the power is the same, the current of single phase power supply is equal to power/220V. Assuming that the power is 1000watt, then the current is 4.54A. The current on each live wire of three phase power supply is equal to one third of the total current, namely 4.54/3=1.5A, so it has a lower requirement to the wire, and thinner wires can be used. It shall be noticed that three phase power supply is generally available only in industrial applications, most households use only single phase power supply (one live wire, one neutral wire and one earth wire), VFD with three phase power supply can’t be used. Single phase power supply VFD can be used in three-phase four-wire power supply areas (connect to one live wire and one neutral wire). So please confirm the power supply of installation before purchase.

In general, single-phase VFDs are more convenient, easy to install, and suitable for home and small commercial locations. Three-phase VFDs, on the other hand, are more powerful and are commonly used in industrial production lines and other applications that require higher performance control. If you are looking to purchase a VFD for your home, a single-phase variable frequency drive from ATO would be the optimal choice.