ET201: THREE PHASE SYSTEMS (ANSWER FOR DISCUSSION EXPERIMENT 4)

(ii)       Current

Figure 1.1.4 (b) shows the current in star connection. The value of line current (I_R, I_Y , I_B ) and phase current (I_r , I_y , I_b) are the same.

     

Line current,      I_L:  I_R , I_Y , I_B

Phase current, I_PH :  I_r , I_y , I_b


So, current element in star connection:

              I_L = I_PH


Neutral current (I_N) is the sum of the three current i.e. I_R, I_Y, and I_{B ;} having same magnitude but 120^o difference in phase. Therefore mathematically, the sum of these vectors will make neutral current I_N equals zero.

       I_N = I_R + I_Y + I_B = 0