This file shows an animation of the voltage and how it relates to points on a circle.[br]The 3 live wires in a 3-phase cable each carry an AC voltage - a voltage that varies in time as a sine wave.[br]The voltages are shifted in "phase" so that each one peeks at a different time and the peeks are evenly spaced in time.[br]A sine wave can be seen as a sideways projection of a point moving around a circle.[br]Take the point V1 on the circle. It is projected onto the vertical line at [br]point V1y. The height of this point above the x-axis represents the size[br] of the voltage. We use a peek height of 1 (which is the radius of the [br]circle). In electricity, the peak voltage is 325 volts (RMS voltage is [br]230 V) but we're scaling down that 325 to 1. As V1 moves around the [br]circle, the height if V1y increases and decreases as a sine wave, going [br]from zero to maximum positive to zero to maximum negative and back to [br]zero. This cycle repeats continuously. [br]The graph of this height versus time is shown to the left of the line, just over a single time [br]period after which the cycle repeats.[br]See how V1, V2 and V3 are equally spaced around the circle (120 deg apart) and the time graph [br]shows that the peeks (maximum heights) are reached at equally spaced [br]time intervals.[br]The heights of points V1y, V2y, V3y give the voltage (scaled) on each of the 3 live wires with respect to a neutral wire at [br]zero volts.[br]The difference in voltage between two wires is the same as the difference in heights between the projected points, e.g. V1y - [br]V2y is the voltage between wire 1 and wire 2. On the circle, the length [br]of the green out to V12 is the same as the distance from V1 to V2 and it[br] has the same direction as the line joining V1 to V2. The length of the [br]green radial line is √3 times bigger than the radius of circle. If you know about vectors, V12 is the subtraction of vector V2 [br]from vector V1. The height of projected point V12y is equal to the [br]difference in height between V1y and V2y, including the +/- sign [br]depending on which is higher. The height of V12y goes to a maximum that[br] is √3 times higher than the maximum of V1y or V2y.[br]The voltage difference between any two of the live wires in a three phase power cable is √3 times the voltage of each wire with respect to neutral.