Power factor insight — does pf directly indicate how much of the apparent power is reactive power?

Introduction / Context:
Power factor is widely used to rate loads and size equipment. It is crucial to understand whether it measures real power share or reactive power share within the total apparent power. Misreading pf leads to errors in efficiency and sizing decisions.

Given Data / Assumptions:

• Sinusoidal steady state.
• Apparent power S, real power P, reactive power Q.
• Phase angle φ between current and voltage.

Concept / Approach:
By definition, power factor pf = P/S = cos(φ). It measures the fraction of apparent power that is converted to real power. The fraction of apparent power that is reactive is |Q|/S = sin(|φ|). Therefore, while pf informs you indirectly about reactive content via the complementary relation, pf itself is not a direct measure of reactive share. A low pf suggests significant reactive power, but pf equals the real share, not the reactive share.

Step-by-Step Solution:

Verification / Alternative check:
Example: φ = 60 degrees. Then pf = cos(60) = 0.5, meaning half of S is real power. The reactive fraction is sin(60) ≈ 0.866, which is not equal to pf. This demonstrates the distinction.

Why Other Options Are Wrong:

• Answering “True” would misinterpret specifications such as pf = 0.9 leading or lagging. Those values indicate that 90% of apparent power is real, not reactive.

Common Pitfalls:
Equating low pf with “mostly reactive” without quantifying; always compute Q = S * sin(φ) and P = S * cos(φ) to determine the shares precisely.

Final Answer:
False