Question

Find the equivalent capacitances of the combinations shown in the figure between the indicated points.

Answer 1

Star - Delta

$C_a,C_b,C_c\to C_1,C_2,C_3$

$\frac{1}{C_a}=\frac{\frac{1}{C_1}.\frac{1}{C_2}+\frac{1}{C_3}.\frac{1}{C_2}+\frac{1}{C_3}.\frac{1}{C_1}}{\frac{1}{C_1}}$

Delta - Star

$\Rightarrow \frac{1}{C_1}=\frac{\frac{1}{C_b}.\frac{1}{C_c}}{\frac{1}{C_a}+\frac{1}{C_b}+\frac{1}{C_c}}$

Apply Star - Delta to both questions by taking middle wing associated to $\Delta$.