Real power P, reactive power Q and apparent power S relate by S²=P²+Q².
Real power P=VI cosφ (W), reactive Q=VI sinφ (VAr) and apparent S=VI (VA) with S²=P²+Q². Complex power S=VI*. Utilities bill demand in kVA because reactive current loads the system without doing useful work.
230 V and 10 A at 30° gives P=1.99 kW and Q=1.15 kVAr.
Real, reactive and apparent power describe how AC power is used, stored and delivered, which determines equipment ratings.
Real power P, reactive power Q and apparent power S relate by S²=P²+Q².
Real, reactive and apparent power describe how AC power is used, stored and delivered, which determines equipment ratings.
The volt-ampere, shown as VA or kVA, which is the product of RMS voltage and RMS current.
Transformer losses depend on current and voltage, not on the power factor of the load, so they are rated in apparent power.
Typical applications include sizing a transformer kVA for a building with motor loads, calculating the reactive power a capacitor must supply and choosing a generator rating for a mixed load of heaters and motors.
Study "Reactance" first (topic 41 of 106 in Electrical Engineering). It covers the groundwork this topic builds on.
Power triangle. Instantaneous power pulses at 2f. Only R dissipates average power.
230 V and 10 A at 30° gives P=1.99 kW and Q=1.15 kVAr.
The next topic is "Power factor", which builds directly on this one.
It is classed as Intermediate in Electrical Engineering (topic 42 of 106). It is an intermediate topic. Work through the beginner topics in Electrical Engineering first.
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