12/31/2023 0 Comments 2 phase power calculator online![]() ![]() Play close attention to the polarity in the diagram and notice how we are actually subtracting the two phase voltages: To get to the correct formula for the A line voltage, we have to add the voltages from A to neutral, and from neutral to B. If we measured the A line voltage, which is the same as the voltage across A line and B line, it would look something like this: Now to get to line voltage, we have to measure the voltage across two lines, skipping the neutral. Where the phasor diagram for the phase voltages looks like this: Wye Circuits- Square root three, Line Voltage, Phase Voltage, and the 30 degree Phase Shiftįor a balanced, positive, ABC sequence wye system we will have the following phase voltage vectors when the A phase to neutral voltage is at zero degrees: Or you may also skip and just watch the video demonstration: Video Demonstration: Wye Circuits- Square Root Three Let’s take a look at the math that goes on under the hood to see where it comes from. Or because you either used the square root of three when you shouldn’t have, or forgot to use it when you were meant to. The key of course is to prevent getting questions wrong on the Electrical PE Exam not because your math is incorrect, but because you applied the wrong formula at the wrong time. In the most simplest terms, the square root three is a magnitude multiplier that accompanies a 30 degree phase shift between line voltages and their respective phase voltages for a wye system, and line currents and their respective phase currents for a delta system that is a result of adding (or subtracting) two vectors that are equal in magnitude and 120 degrees apart. However, understanding where the square root of three comes from is a sure fire way to eliminate mistakes in your work from using it incorrectly and increasing your chance at earning your highest score possible on the Electrical PE Exam. Is it necessary to understand where the square root of three comes from for electrical three phase formulas in order to successfully pass the Electrical PE Exam? ![]() When converting the magnitude of phase current to line to line current for a delta system:Īnd when finding the magnitude of three phase apparent power: Most notably when converting the magnitude of phase voltage to line to line voltage for a wye system: We see the square root of three all the time in three phase formulas. Having a solid foundation on where it comes from helps to have a much more intuitive understanding of three phase power circuits and ensures that it is used properly. Why and where do we use the square root of three (1.73) in our formulas when solving questions for the Electrical PE Exam, and just where exactly does it come from? This is one of the top 5 most misunderstood and asked about topics in three phase power. Click here to print this article for your exam references! ![]()
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