Apparent power

Apparent power, written S, is defined as the complex quantity P + jQ. It combines effective (active) power P and reactive power Q at the fundamental frequency. Some revenue meters use a broader definition. In those meters the square of apparent power equals the sum of the squares of active, reactive and distortion power. Monitoring platforms often compute apparent power as the square root of active power squared plus reactive power squared. Meters and inverters report apparent power in kVA, per phase or as a total. A variant called arithmetic apparent power adds up the magnitudes of the individual phase values. Inverters are rated by their continuous or rated apparent output power in kVA. This rating limits the combined active and reactive output. Some grid codes require a constant apparent power setpoint. With that setpoint, the inverter adds reactive power when active power falls below the setpoint. Avoid this mode where a local load is connected, because it can cut active power production.

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• sentence 2: support check: partial - The sum-of-squares relation with distortion power is stated, but the passages do not say it is specific to some revenue meters, as opposed to a general definition.
• sentence 3: support check: partial - One monitoring register uses sqrt(P²+Q²), but the passage does not support 'often' for monitoring platforms.
• sentence 4: support check: partial - Per-phase and total apparent power and the arithmetic variant are stated, but the passages do not clearly give kVA units for both per-phase and total values (some show VA).
• sentence 5: support check: partial - The kVA ratings are shown and a maximum apparent power limit exists, but the passages do not explicitly say the rating limits combined active and reactive output.
• sentence 4: review: partial - The arithmetic apparent power definition and the per-phase L1-L3 values are stated, and kVA appears for one meter, but no passage shows a total apparent power value, and units vary between kVA and VA. -->