If the Δ impedances are Za, Zb and Zc and the Y impedances are Z1, Z2 and Z3, then which one of the following relations is correct?
1
Z1 = ZaZbZc
2
\({Z_1} = \frac{1}{{{Z_a} + {Z_b} + {Z_c}}}\)
3
Z1 = Za + Zb + Zc
4
\({Z_1} = \frac{{{Z_b}{Z_c}}}{{{Z_a} + {Z_b}+{Z_c}}}\)