When the voltage across the delta winding is calculated from the line to ground voltage, what factor is used?

When calculating the voltage across a delta winding from the line-to-ground voltage in a three-phase system, the factor that is used is √3. This relationship arises from the way voltages in a three-phase system are related to one another.

In a three-phase system, the line-to-line voltage (the voltage measured between any two of the three conductors) is higher than the line-to-ground voltage (the voltage measured between one conductor and the ground). Specifically, the line-to-line voltage is √3 times the line-to-ground voltage.

This means that if you know the line-to-ground voltage, you can determine the line-to-line voltage by multiplying by √3. Conversely, when moving from line-to-ground voltage to delta winding voltage, the same √3 factor applies, since the delta configuration effectively uses the line-to-line voltage as its operating voltage.

Understanding this relationship is crucial in power system analyses, as accurate voltage calculations are necessary for ensuring system reliability and safety. Using the correct factor helps in the design and operational maintenance of electrical systems within the parameters set by NERC and other regulatory bodies.