Question

Question 6 (# marks) Which of the following is correct? a) In- phase instantaneous power alternates between + ve and – ve for a 0PF load. b) Quadrature instantaneous power alternates between + ve and – ve for a unity PF load. c) In- phase instantaneous power for a lagging load is an offset sinusoidal varying sine wave. d) Quadrature instantaneous power never goes – ve

Answer 1

In the question it is asked about which of the following statements are correct. Let us discuss all the answers in brief and arrive at our solutions which is given below,

a) In phase instantaneous power alternates between positive and negative for equal cycles of the load. This could happen for zero power factor load as well. Hence, the statement for this problem is correct.

b) From the load diagram of a unity power factor load we can see that the quadrature instantaneous power is alternating in nature between the positive and negative half cycles. Thus, the statement is correct.

c) The in-phase instantaneous power for a lagging or reactive load will be offset sinusoidal varying load experiencing some phase shifts in the load. Thus, the statement given is correct.

d) The quadrature instantaneous power can go negative as well, as positive, and also both varying aperiodically in nature. Thus the statement given is not correct.