Historical
NEMA C12.24 TR-2011
Definitions for Calculations of VA, VAh, VAR, and VARh for Poly-Phase Electricity Meters
This technical report establishes names and mathematical definitions for the Volt-Ampere (VA), Volt-Ampere hours (VAh), Volt-Amperes Reactive (VAR), and Volt-Ampere Reactive hours (VARh) formulae used by poly-phase electricity meters. The mathematical definitions assume static waveforms.
NEMA: National Electrical Manufacturers Association [nema]