Network Analysis

Tutorial on Balanced Three-Phase Circuits - Part 1

In this tutorial, you will study a typical three-phase circuit, and calculate voltages, currents, and power. Consider the problem below.

A three-phase Y-connected generator with a phase voltage of 500 V and a frequency of 60 Hz is connected through power lines to a balanced delta-connected load that consumes 400 kW of power at 0.77 pf lagging. Calculate the power consumed in one phase of the load, the phase voltage of the load, and the line current.

To approach this problem, it is wise to a draw a diagram, as shown below.

The "Y" of the Y-connected generator is drawn upside down for convenience. It was specified that the phase voltage of the generator is 500 V. This is shown on the diagram. Recall that this is the rms voltage. It is shown as a magnitude only. The phase angle can be ignored in balanced three-phase problems.

It is given that the load consumes 400 kW of power at a pf of 0.77 lagging.

What is the power consumed in one phase of the load? Round your answer to the nearest kilowatt.


After you get the answer, please click on an option:
Go on to the next part of the tutorial.
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1999 Thomas G. Cleaver. All rights reserved.