14 Difference Between Single-Phase And Three-Phase Power Supply (With Comparison Table)

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Typically, the term phase in electricity refers to the current or the voltage available in a connected wire as well as a neutral cable. Power supply system is generally classified into two types, namely single phase power supply and three phase power supply. Both power systems use AC power (a type of electric power in which the electric current changes periodically, both magnitude and direction). Three phase power is used to run high loads in industrial and business settings whereas single phase is used in homes to power devices and appliances.

What Is Single Phase Power?

Single-phase electric power is the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. A single phase AC power system consists of two wires referred to as phase (live/line) and the neutral wire. Depending on where you live, the single phase voltage is usually 240V and the frequency is 50Hz.

Single-phase power is the most common type of household power supply; it is used to power lights, televisions and other small appliances such as fans, coolers, heaters, small air conditioners etc

A single-phase load may be powered from a three-phase distribution transformer in two ways:  by connection between one phase and neutral or by connection between two phases. These two give different voltages from a given supply.  For example, on a 120/208 three-phase system, the phase-to-neutral voltage is 120 volts and the phase-to-voltage is 208 volts. This allows single-phase lighting to be connected phase-to-neutral and three-phase motors to be connected to all three phases. This eliminates the need of a separate single phase transformer.

What You Need To Know About Single Phase

  1. In a single phase power supply, the power supply is through a single conductor.
  2. There is only one type of single phase configuration.
  3. The single phase power supply has one distinct wave cycle.
  4. The voltage of the three phase is 240V.
  5. The single phase system has only one phase wire and in case the fault occurs on the network, then the power supply completely fails.
  6. The single phase supply is mostly used in the house for running appliances with small loads such as lights, dryers, heaters and low power motors.
  7. The single phase has two wires, one phase wire and one neutral; which makes the network simple.
  8. The capacity of power transfer in the single phase is minimum.
  9. For the equivalent circuit, the efficiency of the single phase supply is less when compared to three phase supply.
  10. The power delivered by a single phase system fluctuates as it reaches zero three times each cycle.
  11. It is not possible to transmit more power by single phase without losses.
  12. The output of a single phase system is less when compared to that of three-phase.
  13. Prone to power failure.
  14. There are maximum power losses.

What Three-Phase Power Supply?

Three-phase electric power is a method of alternating current power transmission and distribution. It is a common method used by electrical grids worldwide to transfer power. The three-phase system has four conductors i.e three current carrying conductors and one neutral. The cross-section area of the neutral conductor is half of the live wire.

The three-phase system has several advantages like it requires few conductors as compared to the single-phase system. It also gives the continuous supply to the load. The three-phase has higher efficiency and minimum losses.

The three-phase system gives three phase voltage of equal magnitude and frequency. It provides an uninterruptible power i.e if one phase of the system is disturbed, then the remaining two phases of the system continue supplying power. The magnitude of the current in one phase is equal to the sum of the current in the other two of the system.

The voltage between two phases in a three phase power supply is 415V while that between a phase and the neutral is 240V. Hence, you can provide three single phase supplies using a three phase supply. This is how it is normally done for residential and small business loads.

Applications Of Three-Phase Power

  • Used in industrial, manufacturing and large businesses.
  • Three-phase supply is also used in mobile towers, high-density data centers, unmanned systems as well as other appliances that require loads larger than 1000 watts.

What You Need To Know About Three Phase

  1. There are two types of three-phase configurations: Star and Delta.
  2. In a three phase power supply, the power supply is through three conductors.
  3. The three phase power supply has three distinct wave cycles.
  4. The voltage of three phase is 415V.
  5. In the three phase system, in case the fault occurs on any one of the phases, the other two will continuously supply the power.
  6. The three phase supply is used in large industries and for running the heavy loads.
  7. The three phase network is complicated as it is made up of four wires, three phase wires and one neutral wire for completing the circuit.
  8. The capacity of power transfer in the three phase is maximum.
  9. For the equivalent circuit, the efficiency of three phase is high when compared to single phase power supply.
  10. In the three phase system, the power fluctuates but never reaches zero.
  11. It is possible to transmit more power by three phase without losses.
  12. The output of a three phase system is more when compared to that of single phase.
  13. Each phase of a three-phase system can serve as an individual single-phase system.
  14. Less prone to power failure.

Difference Between Single-Phase And Three-Phase Power Supply

BASIS OF COMPARISON SINGLE-PHASE THREE-PHASE
Description In a single phase power supply, the power supply is through a single conductor.   In a three phase power supply, the power supply is through three conductors.  
Types There is only one type of single phase configuration.   There are two types of three-phase configurations: star and delta.  
Wave Cycle The single phase power supply has one distinct wave cycle.   The three phase power supply has three distinct wave cycles.  
Voltage The voltage of the three-phase is 240V.   The voltage of three-phase is 415V.  
System Fault The single phase system has only one phase wire and in case the fault occurs on the network, then the power supply completely fails.   In the three phase system, in case the fault occurs on any one of the phases, the other two will continuously supply the power.  
Application The single phase supply is mostly used in the house for running appliances with small loads such as lights, dryers, heaters and low power motors.   The three phase supply is used in large industries and for running the heavy loads.  
Complexity The single phase has two wires, one phase wire and one neutral; which makes the network simple.   The three phase network is complicated as it is made up of four wires, three phase wires and one neutral wire for completing the circuit.  
Capacity Of Power Transfer The capacity of power transfer in the single phase is minimum.   The capacity of power transfer in the three phase is maximum.  
Efficiency For the equivalent circuit, the efficiency of the single phase supply is less when compared to three phase supply.   For the equivalent circuit, the efficiency of three phase is high when compared to single phase power supply.  
Power Fluctuations The power delivered by a single phase system fluctuates as it reaches zero three times each cycle.   In the three phase system, the power fluctuates but never reaches zero.  
Power Losses It is not possible to transmit more power by single phase without losses.   It is possible to transmit more power by three-phase without losses.  
Output The output of a single phase system is less when compared to that of three-phase.   The output of a three phase system is more when compared to that of single phase.  
Power Failure Prone to power failure.   Less prone to power failure.