ET201:ELECTRICAL CIRCUIT (THREE PHASE PART 5)

The complete emf waveform for three phase system is shown below with corresponds to the angle and magnitude.

Three Phase Voltages (emf)

               

 

a)                  Three phase vector diagram

Alternating voltages may be represented by revolving vectors which indicate their maximum value(or r.m.s values if desired).The actual values of these voltages vary from peak positive to zero and peak negative values in one revolution of the vectors. In Figure 1.1.2 (g) are shown the three vectors representing the voltages of the three phases e_R, e_Y and e_B. Remember, R is the reference; therefore its vector is placed on the 0⁰ plane of x-axis. This vector diagram is rotated to the position where R is on the vertical y-axis to make better understanding as in Figure 1.1.2 (h). The phase different still 120⁰ apart.

  (g) geometri arrangemenT

(h)  conventional arrangement