Question

Full load u.p.f adjustment involves _________

(a) adjusting the loads at unity power factor

(b) applying rated voltage to pressure coil and a p.f. of unity for current coil

(c) only applying rated voltage to pressure coil

(d) only a p.f. of unity for the current coil

The question was posed to me in an online quiz.

My question comes from Electronic Energy Meter, Adjustments in Single Phase Energy meters in division Measurement of Power and Related Parameters of Electrical Measurements

Answer 1

Right option is (c) only applying rated voltage to pressure coil

To explain: Rated voltage is applied to the pressure coil. The current coil is provided with a current at unity p.f. Errors are kept minimum and the position of the brake magnet is so adjusted that disc rotates at the correct speed.