Difference between Single Phase and Three Phase AC Power Supply

The AC power (alternating current) is a kind of electricity where there is frequent change in the current flow direction. At the beginning of the 1900 year, AC power supply is used for businesses as well as homes and now it got expanded to. The system of the power supply is categorized into two type’s namely single phase power supply, as well as 3 phase power supply. For most industrial and business settings, three-phase supply is used to run the high loads, whereas homes are generally supplied by a 1 phase power supply, because home appliances require less power. This article discusses the difference between single phase and three phase power supplies and how to know either single phase or three phase.

What is Phase in Electricity?

Generally, the phase-in electricity is the current or the voltage among an existing wire as well as a neutral cable. Phase means the distribution of load, if a single wire is used, an additional load will occur on it & if three wires are used then loads will be separated between them. This can be called as less power for 1-phase and more power for 3-phase.

If it is a 1-phase system, it includes two wires and when it is a 3-phase system, then it consists of either 3 wires (or) four wires. Both the power systems like single phase as well as three-phase use AC power to refer units. Because the current flow using AC power is always in the direction of alternating. The main difference between these two supplies is the reliability of delivery.

Single Phase Supply

In the entire electrical domain, 1 phase supply is the delivery of AC power by a system in which there is a simultaneous change in all the supply voltages. This type of power supply sharing is utilized when the loads (home appliances) are generally heat and lightning included with huge electric motors.

When a 1 phase supply is connected to an AC motor, it doesn’t generate a rotating magnetic field, instead, single phase motors require additional circuits for the operation, but such electric motors are rare which have the power rating of nearly 10 kW. In each of the cycles, a 1 phase system voltage achieves a peak-value two times; the direct power is not stable.

Single Phase Waveform
Single Phase Waveform

A load with single-phase can be power-driven from a three-phase sharing transformer in two techniques. One is with the connection between two phases or with the connection between one phase and neutral. These two will give dissimilar voltages from a given power supply. This type of phase supply provides an output of nearly 230V. The applications of this supply are utilized for running small home appliances such as air conditioners, fans, heater, and many others.



The benefits of choosing a 1 phase supply are because of the following reasons.

  • The design is less complex
  • Design cost is less
  • Enhanced efficiency which delivers AC power supply of nearly 1000 watts
  • It holds the ability to deliver a maximum of 1000 watts power
  • Employed in multiple kinds of industries and applications


The applications of single-phase supply include the following.

  • This power supply is applicable for homes as well as businesses.
  • Used to supply plenty of power for homes, as well as for non-industrial businesses.
  • This power supply is sufficient to run the motors up to about 5 horsepower (hp).

Three Phase Supply

The three-phase power supply includes four wires which consist of one neutral along with three conductor wires. The three conductors are away from phase & space and they have a phase angle of 120º from each other. 3 phase power supplies are utilized as a single-phase AC power supply.

For the operation of small load, 1-phase AC power supply, along with the neutral, can be chosen from the 3-phase AC power supply system. This supply is constant and will not be dropped to zero value. The power of this system can be illustrated in two configurations namely star connection (or) delta connection. The connection of star configuration is used in long-distance communication as it includes a neutral cable to the error current.

Three Phase Waveform
Three Phase Waveform


The advantages of three-phase supply over single phase are because of the following reasons:

  • The 3 phase power supply needs less copper
  • It shows the minimal risk for employees who are operating with this system
  • It has a greater conductor efficiency
  • Labor who are working in this system also receives wages
  • It even holds the capability to function with an extended range of power loads

Three Phase Supply Applications

The applications of the three-phase supply include the following.

  • These types of supplies are used in power grids, mobile towers, data centers, aircraft, shipboard, unmanned systems, as well as other electronic loads larger than 1000 watts.
  • It is applicable to industrial, manufacturing, and large businesses.
  • These are used in power-hungry and high-density data centers too.

Key Differences between Single Phase & Three Phase Supplies

The key differences between a 1 phase and three phases include the following.

Feature Single Phase Three Phase
Definition Single phase power supply operates using a single conductor 3 phase power supply operates using three conductors
Wave Cycle It has only one distinct wave cycle It has three distinct wave cycles
Connection of Circuit Need just a single wire to connect with the circuit This power phase requires three wires for connection with the circuit
Output Voltage Levels Delivers a voltage level of almost 230V Delivers a voltage level of almost 415V
Phase Name The phase name of the single phase is split phase There is no specific name for this phase
The ability of Power Transfer It has minimum capacity for the power transmission This phase holds the maximum capacity for transmission of power
Circuit Complexity 1 phase power supply can be constructed simply The construction of this is complicated
The occurrence of Power Failure There will be a frequent failure of power No power failure happens
Loss The loss in single phase is maximum The loss in the 3 phase is minimum
Efficiency It has minimal efficiency It has maximum efficiency
Cost It is not expensive than 3 phase power supply It is a bit costly than single phase
Applications Used for home applications Three phase power supply is used in huge industries to run heavy loads.

The most confusing concept that people come across here is “how to identify single phase and 3 phase”?

The answer lies in the identification of the main switch width. Single phase power supplies are one pole wide while three phase power supplies have a width of three poles.

How to Convert Single Phase to Three Phases?

As this is the most crucial concept to be known, the following points explain the conversion of a single phase to three phases.

When there exists a large-sized compressor without any three-phase power supply corresponding to the system that the local grid is constructed, there exist multiple paths to solve this and to provide proper power for the compressor. The prominent solution is to convert a three phase motor into a 1 phase motor.

For this conversion, there exist mainly three kinds of three-phase converters.

  • Static Converter – When the three phase motor does not get initiated with the 1 phase power, then it can operate on 1 phase owner once gets started. This happens with the support of capacitors. But this method has not that much efficiency and also less time span.
  • Rotary Phase Converter – It functions like the integration of a generator and a three-phase operated motor. It consists of idler type of motor which when it is in motion, produces power and because of this whole set-up might stimulate a three phase system in a proper way.
  • Variable Frequency Drive Converter – It operates using inverters where those generate AC at any frequency levels and reproduce almost all the conditions internal to the 3 phase motor.

Thus, this is all about the difference between single phase and 3 phase power supplies, and a comparison chart. From the above information finally, we can conclude that with the right care in the design part of a power supply, the designer can make suitable advice for the highest efficiency & cost savings of your project.

Choosing a single phase (or) three-phase system mainly depends on the power requirements of a particular application. Anyway, a well-designed component will ensure a reliable as well as robust power distribution. Here is a question for you, what is the main functionality of three phase & single phase power supplies?