Line Voltage and Phase Voltage: Differences to Remember 

Line Voltage and Phase voltage are the two most important prospects of Voltage in Physics. Many of you are confused about these two topics. We will discuss what is Voltage, Line Voltage, and Phase Voltage and the Distinguish between Line Voltage and Phase Voltage

In this article, we will be resolving your problems regarding Voltage and the relations of voltages with delta and also with stars. Keep reading this article to clear your doubts on this topic. 

What is Voltage?

Voltage describes the quantitative expression of the potential difference between the two points in an electronic field. Voltage is termed using the symbol “V” or “E.” 

With the increase of Voltage, the flow of electrical current increases ( the quantity of charge carriers passes a fixed point at per unit time) through a conducting or semiconducting material for a given resistance to the flow. 

The S.I. unit of Voltage is “Volt,” expressed by the letter V. As we can say that one volt of electricity will drive one coulomb (6.24 x 1018) charge carriers, like electrons, with a resistance of 1 ohm in 1 second.

Voltage can also be taken as the amount of potential and significant energy between two points. As both points are on different potential energy, one will have higher potential energy, whereas the other will have lower potential energy. The difference of potential energy between these two points is called Potential difference or Voltage.

Further, you will get insights on Line Voltage, Phase Voltage, and Distinguish between Line Voltage and Phase Voltage.

Line Voltage

The Line voltage is the important difference between any two lines or phrases that are in existence in the system. 

  • Line Voltage is significantly referred to by V line or V L-L. 

They are none other than conductors or windings of a coil. If M, N, and O are the three phases where M (refers to red phase), N (refers to yellow phase), and O (refers to blue phase, then the voltage difference between these phases can be,

M and N

N and O.

O and M. 

All the above forms the line voltage. 

Line Voltage has a standard voltage of 120 Volts. 

Phase Voltage

The potential difference between a phase (R, Y, or B) and a neutral junction point is the potential difference. It is denoted by V phase = VR (voltage in red phase) = VY (voltage in yellow phase) = VB (voltage in blue phase).

Likewise, the line current is in one phase, whereas phase current is present inside the three-phase connection.

To understand line voltage and phase voltage further, we first need to understand the several types of three-phase connection systems.

Relationship Between Phase Voltage and  Line Voltage as shown in Star Connection :

Let’s assume that there are three rolls of wire connected by a common connection point. The wires departing from each roll to the load are called the line wires, and the conductors themselves refer to the phases. 

The system is referred to as a three-phase three-wire star connection system. If you attach a neutral roll to the shared middle point, it is referred to as a three-phase four-wire star connection system. 

The line and phase voltage show the relationship as follows:

  • Vline = √3Vphase
  • Line current = Phase current.

Relationship among Line Voltage And Phase Voltage as shown in Delta Connection :

If we talk about the Delta connection, the three different ends of phases are connected and form a different triangular loop and are not having a common neutral point as it is in Star Connection. Moreover, in the Delta connection, the line voltage is equal to the phase voltage. 

The line and phase voltage sound-related as follows: 

  • Vline = Vphase 
  • Line current = √3× Phase current.

Note: Line Voltage and Phase Voltage are considered as proportional to one another. It means that incremental to line voltage will lead to an improvement of phase voltage. 

Distinguish between Line Voltage and Phase Voltage:

The line voltage is referred to as the difference between two phases in a three-phase system. It is denoted by Vl volts. The phase voltage dignifies the significant difference between one phase to the neutral point in any three-phase system, and Vph denotes it in volts. 

Line Voltage is measured across an individual load impedance, whereas the Phase Voltage is measured across the two lines. 

Single-phase Voltage or the Phase Voltage will have the convolution connected so that one phase and neutral are available to the customer. Also, the Phase Voltage value is 230 V. 

It is common to find single-phase Voltage ranging from 115 V, 127 V, 220 V. Microwaves, Lightning, automatic gates, portable welding equipment are powered by Phase Voltage. 

Line Voltage or three-phase Voltage has the windings joint so that the three phases and the neutral are available to the consumer’s installations. Three-phase voltages have a value between 400 V and 230 V. 

It is common to find 208 V, 220 V, and 380 V Line voltage. Electronic motors, Pumping systems, lifts, large compressors are the equipment that is supplied with three-phase Voltage or Line Voltage.

To reduce the physical environment loss during the power transmission, it is justified to work with three-phase or Line Voltage as they provide gain in electrical power. Moreover, in a system of electrical power, the three-phase Voltage is three times higher than if the same system worked with single-phase Voltage. 

P(three-phase voltage)= 3 X P (Single-phase voltage) 

Single-phase or Phase voltage are provided for use at home, whereas industries are provided with three-phase or Line voltage. For determining the generator for a customer, it is important to define the choice between single and three-phase. For the generator requiring three-phase voltages, three-phase generators should be chosen. 


As we discussed, voltage is the quantitative expression of the potential difference between two points in an electric field. And after that, we had discussed distinguishing between Line Voltage and Phase Voltage that Line Voltage and Phase Voltage are Directly proportional to each other and how the potential difference plays an essential role in Voltage.

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