Which statement best describes the purpose of metering apparent energy in billing?

• A. To bill for reactive energy only
• B. To bill for total energy excluding reactive components
• C. To bill for total energy including real and reactive components
• D. To measure voltage fluctuations only

Answer: (C)

Metering apparent energy focuses on the total energy exchange between the system and the load, which includes both the real energy that does useful work and the reactive energy that sustains magnetic and electric fields. This total is represented by apparent power, S, which combines active power P and reactive power Q through S = sqrt(P^2 + Q^2). In billing terms, measuring apparent energy means charging for this overall energy flow (often reflected as kVAh), not just the usable work (kWh) or only the reactive portion (kVARh).

For example, if a load delivers 100 kW of real power with 50 kVAR of reactive power, the apparent power is about 111.8 kVA. Billing based on apparent energy would reflect that larger total energy exchange, accounting for both P and Q. The other options describe billing specifics that don’t capture the whole energy interaction: reactive energy alone, total energy excluding reactive components, or voltage fluctuations alone.