Single Phase VS Three Phase: What’s the Difference?

AC power can be divided into single-phase (single-phase) and three-phase (three-phase). Generally speaking, single-phase power supplies are used where power demand is low. In short, it is used to run small devices. The three-phase power load is large and can run large-scale machinery in the factory.

When it comes to single-phase and three-phase, the main difference is that the former is used for household electricity needs and the latter is used to run heavy machinery. This article discusses the differences between them so that you can know what a three-phase power supply is and understand how they work.

1. What is a single-phase power supply and its characteristics?

In single-phase electricity, the power supply voltage of the power supply changes at the same time. Generally speaking, single-phase current is called “residential voltage” because it is mainly used in households. When it comes to distributing power, single-phase connections use neutral and phase wires. The neutral wire serves as the return path of the current, while the phase wire carries the load.

In a single-phase connection, the voltage starts at 230 volts and the frequency is about 50 Hz. Since the voltage in the single-phase connection continues to rise and fall, it cannot provide constant power to the load. Let us discuss the advantages and disadvantages of using a single-phase power supply.


  • Single-phase connection is suitable for household goods and residences. This is because most electrical appliances require a small amount of electricity, such as TVs, lights, fans, refrigerators, etc.
  • The single-phase connection function is simple and common. It consists of a compact and lightweight unit, and when the voltage is higher, the current through the wire will be lower.
  • Due to the power reduction, it ensures that the power from the single-phase connection runs in an optimal state and effectively transmits power.
  • Single-phase connection works best on equipment below 5 horsepower.


  • Heavy equipment such as industrial motors and other machinery cannot be operated with single-phase power.
  • Small motors smaller than a single kilowatt cannot run on a single-phase power supply because they lack the initial torque required by the motor. Therefore, for the smooth operation of the motor, additional equipment is required, called a motor starter.

2. What is a three-phase power supply and its characteristics?

Through the three-phase power connection, you can get three independent power services. So, how does the three-phase work? Each segment of current can reach the maximum voltage and complete one-third of the time in one cycle. In short, the voltage of the three-phase power connection remains unchanged.

Moreover, it will never drop to zero. If you are running heavy equipment, it is important to understand the three-phase power supply and how it works. It requires three wires and a neutral wire to be side by side in a three-phase connection. The distance between the wires is 120 degrees.

In addition, you can find two different types of configurations in the three-phase connected power supply: star type and delta type. The star circuit configuration requires ground and neutral. The delta circuit configuration does not require a neutral wire.

In addition, a variety of high-voltage equipment can use the power supply of the Delta circuit configuration. The following are the advantages and disadvantages of using three-phase power.


  • Because it has sufficient torque, no additional starter is required for heavy industrial motors.
  • Efficient operation of large machinery. Industrial and commercial loads prefer three-phase connections because of the large amount of power required.
  • When the number of phases of the power supply system increases, the voltage of the three-phase power supply becomes smoother.
  • The three-phase connection does not require excessive conductive materials to transmit power. Therefore, when it provides a cost-effective solution, the three-phase connection is more economical.


  • The biggest disadvantage of the three-phase connection is that it cannot handle overloads. Therefore, it may damage the equipment, and the possibility of expensive repairs is higher. This is because the cost of a single component is expensive.
  • Due to the high unit voltage, the three-phase power connection requires high insulation costs. The insulation varies with the voltage, and the size of the wire depends on the power distribution.

3. What is the difference between single-phase power supply and three-phase power supply?

Here is an important difference between single-phase and three-phase connections.

  • In a single-phase connection, current passes through a single conductor. On the other hand, a three-phase connection consists of three separate conductors needed to transmit power.
  • In a single-phase power supply system, the voltage can reach 230 volts. But in a three-phase connection, it can withstand voltages up to 415 volts.
  • For smooth current flow on a single-phase connection, it requires two separate wires. One represents the neutral line and the other represents single phase. These are all necessary to complete the circuit. In a three-phase connection, the system needs a neutral wire and a three-phase wire to complete the circuit.
  • The maximum power transmitted on a three-phase connection compared to a single-phase power supply.
  • A single-phase connection consists of two wires, forming a simple network. But in the case of a three-phase connection, the network is complicated because there are four different wires.
  • Since the single-phase connection has only one phase wire, if any failure occurs in the network, the entire power supply will be interrupted. However, in a three-phase power supply, if any change occurs in one phase, the other phases can still work. Therefore, there is no power outage.
  • In terms of efficiency, single-phase connection is lower than three-phase connection. This is because in the same circuit, a three-phase power supply requires fewer conductors than a single-phase power supply.

4. Conclusion

Therefore, when it is single-phase vs three-phase power supply, a residential electrical connection does not need a three-phase connection, because all electrical appliances do not need such a connection. However, if you have several heavy electrical appliances in your house, maybe you may need a three-phase connection.


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