What should power factor be (preferably)?

• A. 0.5
• B. 0.8
• C. 1.0
• D. 0.95

Answer: (C)

Power factor tells you how effectively the current in a circuit is being used to do real work. The ideal situation is unity, meaning the voltage and current are perfectly in phase and all the power drawn from the source is real power, with no reactive power bouncing back and forth.

When the power factor is 1.0, for a given amount of real power, the current required is minimized. That reduces I^2R losses in conductors and equipment, lowers the apparent power the system must carry, and makes distribution and downstream equipment more efficient. In real systems, inductive or capacitive effects cause reactive power and phase shifts, so engineers aim for as close to unity as practical. A value like 0.95 is good and often acceptable, but 1.0 is the ideal goal.