The first step in reducing energy consumption is measuring how much you are using. Energy consumption consists of two primary components, power and demand. Power, measured in watts, indicates the rate at which energy is expended. Demand, measured in volt-amperes (VA), indicates the requirement that a customer places on the utility to deliver voltage and current without regard to the efficiency of that delivery of whether or not it does actual work. Power is usually less than demand and the ratio between the two, kW/kVA is called the power factor. Utilities often collect a penalty charge based on the power factor. Three phase energy distribution used in most facilities further increases the complexity of energy consumption measurement. Measuring real power requires meter that can simultaneously measure voltage, current, power and demand over at least a one second period. Harmonic currents, produced by input rectifier loads and reflected back into the supply system, also reduce power factor. A power quality analyzer such as the Fluke 435 will measure all of these elements over time in order to provide an accurate picture of power consumption. Power quality analyzers typically measure energy usage for an hour while power loggers perform 30 day load studies to provide an even better understanding of power consumption over time.
13 years ago