| Interactive Tool |
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This interactive is fairly simple in its control, having a start pause button in the lower left hand corner which controls a slow moving animation of the rotation and drawing of a sine wave across 360° and a slider which can be used to advance or retard this movement to a given position in the cycle.
Its default starting position is to draw the sine wave of a one cycle in Phase 1 (L1) from its start at 0V through a peak of 230V at 90° back through 0V at 180°, through - 230V at 270° back to 0V at 360°. This cycle represents 1Hz or 0.02secs in the UK which has a 50Hz supply. A single phase supply is supplied to domestic dwellings and is often denoted with a circle with a slash through 1∅
Three seperate live supplies are often used in industry for motors. In this case these 3 different lives are out of step (or out of phase with each other) by 120°
By clicking the checkboxes L2 and L3 these 2 extra phases can be introduced into tool and the 2 extra sine waves drawn in alongside but out of phase with the original single phase supply L1.
When a checkbox reveals a new phase in the tool it also reveals the voltage that is present on that phase with respect to earth at any given point in the cycle. This voltage is indicated with a negative symbol when in the negative part of that phases cycle.
When two or more checkboxes are selected extra info is revealed showing the diffference in voltage between those two phases at each point of the cycle. This voltage value is always positive and cycles between 0V and approx 400V between pairs of phases in each cycle and can be seen as the height difference between the dots on the corresonding sine waves.
When a single phase supply is at 230V and the 3 phases are each seperated from each other by 120° the voltage difference between any two phases will top out at 400V. This can differ if the loads on the phases have different characteristics from one another that cause them to separate by different angles but this requires much deeper explanation than in this L2 demo.
As mentioned in single phase supply explanation 3 phase supplies can also be denoted in shorthand as follows 3∅
The difference in voltage between single and three phase voltage levels is a factor of √3