Specifications

G4500 BLACKBOX PORTABLE OPERATIONAL MANUAL

August 2010

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Energy Section

Energy is defined as power consumed over time. In electrical distribution sys-

tems, the unit of time is one hour for all energy measurements and the kWh is

the basis for payment for buying and selling energy. This chapter focuses on the

flow of energy or power both within a system (active, reactive) as well as the

flow of power to and from the system to the grid (delivered or received). The

following are commonly used terms in describing energy flow within a system:

 Active or Real: The portion of power flow that, averaged over a complete cycle of the

AC waveform, results in the net transfer of energy in one direction expressed as kWh.

 Reactive /Volt Amperes Reactive (kVArh): Energy that flows back and forth with no

actual power flow. Reactive power flow transfers no net energy to the load and is some-

times referred to as wattless power.

 Apparent: The combination of active and reactive energy (kVAh).

 Power Factor: The ratio between real power and apparent power (a value between 0

and 1).

Consumption & Demand

Energy is produced and consumed within an electrical distribution system. Some

sites produce energy for the grid (Received Energy), others consume energy

from the grid (Delivered Energy), and still others both consume and produce en-

ergy for/from the grid. The Net Consumption is the difference between energy

that is used and produced. Therefore, a negative value for Net Consumption in-

dicates that the site is producing more than it is consuming, or a received net

consumption.