Reactive power is power associated with energy storage in inductors and capacitors; what is its SI unit?

Reactive power is power associated with energy storage in inductors and capacitors; what is its SI unit?

• A. Volt-amps reactive (VAR)
• B. Real power is energy used by resistors; unit is watt (W).
• C. Apparent power is the combination of real and reactive power; unit is volt-amperes (VA).
• D. Reactive power is energy wasted as heat; unit is joules (J).

Answer: (A)

Reactive power is the portion of power that is alternately stored and returned by inductors and capacitors, not actually consumed as heat or work in a cycle. In AC analysis, real power (the energy converted to work/heat) is measured in watts, apparent power (the total capability to carry power) is in volt-amps, and the reactive portion is designated with a different unit to reflect its nature. The relation P = VI cosφ, Q = VI sinφ, and S = VI helps see the distinction: P is real power in watts, Q is reactive power in volt-amps reactive, and S is apparent power in volt-amps. Therefore, reactive power uses the unit volt-amps reactive (VAR).

Reactive power is the portion of power that is alternately stored and returned by inductors and capacitors, not actually consumed as heat or work in a cycle. In AC analysis, real power (the energy converted to work/heat) is measured in watts, apparent power (the total capability to carry power) is in volt-amps, and the reactive portion is designated with a different unit to reflect its nature. The relation P = VI cosφ, Q = VI sinφ, and S = VI helps see the distinction: P is real power in watts, Q is reactive power in volt-amps reactive, and S is apparent power in volt-amps. Therefore, reactive power uses the unit volt-amps reactive (VAR).