The power triangle
Apparent power S is measured in VA, real power P in W and reactive power Q in var.
P = S × PF and Q = √(S² − P²).
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Real, reactive and apparent power from RMS voltage, current and power factor.
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S = VI, P = VI cos φ and Q = VI sin φ for a sinusoidal single-phase load.
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Assumptions and limits.
- Single-phase sinusoidal supply with constant RMS voltage and current.
Frequently asked questions
Why is kVA not the same as kW?
kVA includes reactive power. kW is the real power that performs work.