Electrical
Apparent vs Real Power (kVA / kW)
01 — Definition
Real power (kW) is what does the actual work; apparent power (kVA) is the voltage × current product the source has to supply. Power factor (PF) = kW / kVA. Reactive loads — LED drivers, motors — draw current out of phase with the voltage, so the kVA exceeds the kW. And since generators and distribution are rated in kVA, you size them on apparent power, not on the sum of the fixture wattages.
02 — In the field
Size generators and distros in kVA, not kW. A rig of 40 kW of LED at PF 0.9 demands about 44 kVA: a 40 kVA generator will overload. Always divide total watts by the worst-case power factor.