Question

If an 8/9ohm, 4/3ohm and 2/3ohm resistor is connected in star, find its delta equivalent.

(a) 4ohm, 3ohm, 2ohm

(b) 1ohm, 3ohm, 2ohm

(c) 4ohm, 1ohm, 2ohm

(d) 4ohm, 3ohm, 1ohm

The question was posed to me in a job interview.

This question is from Star Delta Transformation in portion Network Theorems of Basic Electrical Engineering

Answer 1

The correct option is (a) 4ohm, 3ohm, 2ohm

To elaborate: Using the formula for the star to delta conversion:

R1=8/9+4/3+(8/9)*(4/3)/(2/3)

R2=8/9+2/3+(8/9)*(2/3)/(4/3)

R3=2/3+4/3+(2/3)*(4/3)/(8/9).