Three phase line or phase voltage?

In summary, three loads are connected in star across a 3 phase, 400 V, balanced RYB supply. The line currents and phase voltages can be determined using the given loads and supply information. The neutral shift voltage, VON, is also calculated. The solution assumes that the 400 V is the line voltage, not the phase voltage, and that all calculations are done in RMS values.
  • #1
Raghav Gupta
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Homework Statement


Three loads ZA = 10∠0° Ω; ZB = 15∠-30° Ω and ZC = 20∠45° Ω are connected in star across a balanced, 3 phase, 400 V, RYB supply. Determine (a) line currents (b) Phase Voltages (c) Neutral shift voltage, VON

Homework Equations

The Attempt at a Solution


My query is that in question I am taking 400 as rms phase voltage of supply but I saw the solution and they have done by considering that voltage as line to line rms voltage, why that is so?
Later we should also multiply voltage by√2 but are we required to keep the solution in rms only?
 
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  • #2
By convention, 3 phase supplies are described by their line voltage, i.e. the voltage between any pair of phases.

By convention, AC supplies are always described by the RMS value of their sinusoidal waveform.
 
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1. What is a three phase line?

A three phase line is an electrical power transmission line that has three conductors, or wires, each carrying alternating current (AC) at the same frequency, but with a phase difference of one third of a cycle between them.

2. What is the purpose of having three phases?

Having three phases allows for a more efficient and balanced distribution of electrical power. Each phase can carry the same amount of power, resulting in a higher overall power capacity compared to a single phase system.

3. What is the difference between phase voltage and line voltage?

Phase voltage is the voltage measured between any one of the three phases and the neutral wire. Line voltage is the voltage measured between any two of the three phases. The line voltage is √3 times the phase voltage in a three phase system.

4. How is three phase power used in different applications?

Three phase power is commonly used in industrial and commercial settings, as well as in large residential buildings. It is used to power heavy machinery, motors, pumps, and other high power devices. It is also used for power transmission over long distances.

5. What are the advantages of using three phase power over single phase power?

The main advantage of three phase power is its higher power capacity and efficiency. It also allows for smaller and more economical wiring and equipment, as well as a more balanced distribution of power. Three phase power also results in smoother operation of devices compared to single phase power.

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