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3-Phase Motor and VFD Wiring Diagram with Single-Phase Supply

Last Updated on: 2024-02-14T03:31:05Z , , ,


Hey, in this article, we are going to see the wiring diagram for operating a 3-phase motor on a single-phase supply with VFD(Variable Frequency Drive). In some locations especially in remote or rural areas, single-phase power may be more easily available than three-phase supply. In such cases, we may required to operate a 3-phase motor single-phase supply. A VFD is an electronic device that can vary the frequency and voltage of the output power. Even some VFDs give features for operating three-phase motors using only a single-phase power supply. They take a single-phase power supply and convert it into three-phase power with adjustable frequency and voltage.

In this system generally, the VFD is connected to the single-phase power supply. The output of the VFD is then connected to the 3-phase motor. The VFD regulates the frequency and voltage to control the speed and direction of the motor. Here, we need to rectify that the 3-phase motor is compatible with VFD operation because some motors may require modifications or special configuration when operated with a VFD. Also, we need to choose a VFD that is appropriate for the motor's power rating because Overrating or underrating the VFD can cause inefficient operation or unexpected damage to the motor.


Wiring Diagram


Here in the below wiring diagram, you can see the connection between the 3-phase Motor and VFD with the Single-Phase Power Supply.

Wiring Diagram for Operating 3 Phase Motor on Single Phase Supply with VFD


Apparatus List

  • Single Phase MCB
  • Variable Frequency Drive or VFD(Single Phase Supported)
  • Three Phase Motor
  • Selector Switch
  • Dynamic Braking Resistor(Optional)
  • Potentiometer(Optional)

Connection Description

  1. First of all the single-phase power supply is connected to a single-phase MCB.
  2. Then the output of the MCB is connected to the VFD(L, N Terminals)
  3. The output of the VFD(U, V, W Terminals) is connected to the 3-phase Motor.
  4. Now the common terminal of the selector switch is connected to the Ground(GND) terminal of the VFD.
  5. Another two terminals of the selector switch are connected to the DI1 and DI2 terminals of the VFD. Here, DI means Digital Input.
  6. Here, the Dynamic Braking Resistor is connected to the P+ and PB terminals of the VFD. In some VFDs, these terminals are also known as DC+ and DC-
  7. The potentiometer is connected to the VFD with Ground, AI1, and 10V terminals. Here, AI means Analog Input.

Working Principle


Here, the single-phase power supply is connected to a single-phase MCB (Miniature Circuit Breaker). This MCB is used as a protective device to control and protect the whole circuit against overcurrent.

The output of the MCB is connected to the VFD (Variable Frequency Drive) at the L (Line) and N (Neutral) terminals. The VFD will convert the single-phase input power into three-phase output power with adjustable frequency and voltage.

The output terminals U, V, and W of the VFD are connected to the corresponding terminals of the 3-phase motor. These connections help to deliver the controlled three-phase power from the VFD to the motor, providing the feature of speed and direction control through the VFD.

The common terminal of the selector switch is connected to the Ground (GND) terminal of the VFD which helps to establish a common ground reference for the system.
Two other terminals of the selector switch are connected to the Digital Input 1 (DI1) and Digital Input 2 (DI2) terminals of the VFD. These help to provide digital input signals to the VFD for forward and reverse commands.

The Dynamic Braking Resistor is connected to the P+ (Positive) and PB (or DC-) terminals of the VFD which are associated with the DC bus of the VFD. Dynamic braking is a method used to quickly dissipate the excess energy during the braking where the resistor plays a role in this braking process.

The potentiometer is connected to the VFD using the Ground, AI1 (Analog Input 1), and 10V terminals. This potentiometer is used to provide analog input to the VFD to control the speed of the motor.


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3-Phase Motor and VFD Wiring Diagram with Single-Phase Supply 3-Phase Motor and VFD Wiring Diagram with Single-Phase Supply Reviewed by Author on February 13, 2024 Rating: 5
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