ABSTRACT
Per phase analysis can be developed for the simple three-phase system illustrated in Figure 2.1 by solving Equations 2.1a through 2.1d. A¶er line and residual currents are calculated, voltage can be calculated:
V I Z Source Z System Z Load I Z SystemA A A A A R R− × + + − × =( ) 0 (2.1a)
V I Z Source Z System Z Load I Z SystemB B B B B R R− × + + − × =( ) 0 (2.1b)
V I Z Source Z System Z Load I Z SystemC C C C C R R− × + + − × =( ) 0 (2.1c)
I I I IA B C R+ + − = 0 (2.1d)
Solving Equations 2.1 is tedious because all values are vectorial, that is, voltages are represented as a voltage magnitude with an associated angle and impedances are represented as complex impedances that include resistance and reactance components. In addition, the residual system impedance (ZR) is the parallel combination of neutral and earth impedance.
