Question

A 3 phase balanced supply feeds a 3-phase unbalanced load. Power supplied to the load can be measured by ___________

(a) 2 Wattmeter and 1 Wattmeter

(b) 2 Wattmeter and 3 Wattmeter

(c) 2 Wattmeter and 2 Wattmeter

(d) Only 3 Wattmeter

The question was posed to me in a job interview.

This interesting question is from Advanced Problems on Application of Laplace Transform topic in division Application of the Laplace Transform in Circuit Analysis of Network Theory

Answer 1

The correct choice is (b) 2 Wattmeter and 3 Wattmeter

Easiest explanation: We know that, a minimum of 2 wattmeters is required to measure a 3-phase power. Also, power can be measured by using only one wattmeter in each phase. Hence, power supplied to the load can be measured by 2 Wattmeter and 3 Wattmeter methods.