Question

For an alternator, the specified load angle should be _________ for an impedance angle of ‘θ’.

(a) δ=θ

(b) δ=90-θ

(c) δ=90+θ

(d) δ=-θ

The question was posed to me during an interview for a job.

Question is taken from Power Flow Through an Inductive Impedance topic in division Efficiency and Regulation of Electrical Machines

Answer 1

Right option is (a) δ=θ

To explain I would say: dP/dδ = EVcos(δ+α) = 0

              δ = 90-α=θ.