Rockwell Automation 1404-M4_M5_M6_M8 Powermonitor 3000 User Manual, Firmware rev. 3.0 or LATER - Manual (Page 350)

350 Publication 1404-UM001F-EN-P - November 2009
Glossary
watt demand
Power during a predetermined interval. The highest average, for
example, Peak demand is commonly used for billing.
watt hour (Whr)
The number of watts used in one hour. Since the power usage varies,
it is necessary to integrate this parameter over time. Power flow can
be either forward or reverse.
wattmeter
An instrument for measuring the real power in an electric circuit. Its
scale is usually graduated in watts, kilowatts, or megawatts.
volt ampere reactive hours (VARH)
The number of VARs used in one hour. Since the value of this
parameter varies, it is necessary to integrate it over time. VARs can be
either forward or reverse.