Three phase signals (voltage and/or currents) can be represented by a rotating space vector in two dimensions. This applet explores the operation of a simple circuit consisting of two sinusoidal sources interconnected by an inductor through the use of space vectors and voltage/current time plots. The rotating vector is visualised by moving the ‘red timeline’ on the time graphs or by dragging the ‘red arrowhead’ on the uN voltage vector. Three phase sinusoidal voltages and currents produce a space vector that follows a perfect circle.

When a voltage magnitude and/or phase angle difference exists between the two voltage sources then a current must flow in the inductor. This can be seen from the time plots and the space vector. The voltage across the inductor gives rise to a current that is lagging by 90 degrees. Although this is observable in the time plots the 90 degree relationship is more easily seen in the space vector plot. The magnitude of the current is dependent on the magnitude of the inductor voltage and the inductance value.

• Move the red timeline to view the rotating space vectors.
• Adjust the magnitude and/or phase angle of the uSIN voltage by dragging the red arrowhead or the red dot on the time plot.
• Adjust the phase angle and magnitude of the uN voltage by dragging the red arrowhead.
• Change the inductance value and view the effect on the inductor current magnitude.