# Line Voltage and Phase Voltage Differences with Solved Examples

Line voltage is a system with three-phase and is the major difference between two of the lines or either of the two phases in the present system. The phases are winding on the coil or conductors.

The red phase is denoted by R, the yellow phase is denoted by Y, and the blue phase is denoted by B. The voltage differs between R and Y, B and R, and Y and B from the line voltage.

Phase voltage is the major basic difference between any phase, say R, Y, or B, and the neutral point junction, denoted by a V.

So, what does Line Voltage to Phase Voltage mean?

A line current is a current in any phase and phases current in the three-phase system.

**Star connection**

Imagine there are three wire coils or windings of any transformer attached to a common point of connection. Three of the wires that go further away from the coil towards the load are the line wires. The conductors are what are called the phases.

This is a three-phase typical system of star connection of three-wire. If you attach a neutral wire in the shared point in the middle, this will be a three-phase and four-wired star connection.

**Delta connection**

In the case of a delta connection, all three-phase ends are joined to form a closed loop in the shape of a triangle. There is no one common central point like in the case of a star connection.

**Line voltage**

In the case of a three-phase power system, the line voltage is the difference between the two phases. This is typically phased to phase. VL-L denotes the line voltage. It is the voltage between two points. In the case of a power system, the system voltage means the line to line voltage.

The domestic power supply line is a three-phase and 440 volts. The 440 volts means the phase to phase voltage. If it is mentioned that the single-phase is 230 volts, then this is the major difference between the phase and the neutral, which is 230 volts.

- In the star connection, the line voltage equals 1.732 times the phase voltage.
- A delta connection is where the line voltage and the phase voltage are the same.

**Understanding line current**

The line current is the current measurement in a single phase before a star of a delta arrangement of the component. This is typically the input current and the alternator’s output current.

- It is denoted by IL ampere.
- In a star connection, the line current and the phase current are equal.

**Understanding phase voltage**

In the case of a three-phase system, the major difference between one phase to the neutral point is the voltage phase. This is represented as Vph volts.

- In a Star Connection, the phase voltage is equal to the line voltage divided with 1.732
- In a Delta Connection, the line voltage is equal to phase voltage.

**Understanding Phase current**

A phase current is the measure of the current that lies in the star connection or the delta connection in the case of a three-phase system. Iph denotes this.

- In a star connection, the phase current is the same as the line current.
- In a delta connection:
- Here the Value of √3 = 1.732.

So it means that in any polyphase system, the line voltage is the voltage between two given phases. The phase voltage is the voltage that exists between neutral and the given phase. The line and the phase voltage are proportionate to each other

**Relation between line voltage and phase voltage**

- When the line voltage increases, there is an increase in the phase voltage as well.
- When there is an increase in phase voltage, this will show an increase in the line voltage.

**Difference between the line voltage and a phase voltage**

Let us now list down the differences between the line voltage and phase voltage.

- In a star connection, the line voltage is higher than the phase voltage.
- Line voltage is the difference majorly between two lines or phrases. Phase voltage is the major difference between a neutral junction and a phase.
- In a star connection, the line voltage is equal to √3 times that of the phase voltage.

**Solved examples**

**How to prove the relation between the phase voltage and line voltage?**

- In a supply of three-phase, all phases are placed at a distance of 120 degrees away.
- The line voltage is the difference between two-phase voltages.
- The line voltage between the two phases is a vector difference.
- The intensity of all the phase voltage is the same.
- This is why VYB= √3 V which is the line voltage between two phases, yellow and blue. This is the resultant of two vectors that have the same magnitude and are 60 degrees away.
- Now VYB is the line voltage or the major difference between the blue and the yellow phase. Thus we get the phase voltage as 1/√3 times the line voltage.

**How to calculate power in the line and phase voltage if it is a power connection?**

- The system of three-phase power is the one that is widely used.
- The connection is different from a single-phase system.
- There is the stage of a sine wave in the fluctuating current because the current will vary both in amplitude and direction.
- A single phase will have just one of such a wave. However, in the case of a three-phase system, the current has three components that stay out of the phase by every third of the cycle.
- Every component is in the opposite way to the two other parts combination, but it is the same in magnitude.

**Conclusion**

The voltage that is given in any question is usually a line voltage. The phase voltage, however, will be specifically mentioned. The three-phase 440 volt supply for domestic use is a line voltage. The single-phase 230 volts AC supply is the difference between the neutral junction and the phase or the difference between the phases.

A polyphase system is where the line current and the line voltages are the same. This is a three-phase balanced system. If there are unsymmetrical loads, then the system would usually be unbalanced.