With the introduction of new technologies such as computers, variable frequency motor drives, and other devices into our daily lives, we are also creating more problems for the Energy Engineer. Not only is keeping track of the amount of energy used and the demand for it important now, the power's quality is also a consideration.

Energy Professionals have repeatedly asked Pacific Science & Technology for an affordable way of surveying a particular facility or device's power quality. We've added that capability to one of our customers' favorites. The ELITEpro^TM, which already provides: Volts, Amps, kWh, kW, kVA, kVAr and Power Factor; now provides Harmonic Analysis and Waveform Capture. We believe that this will bring even more value to the ELite Logger, which is already:

The buttons along the lower left side of the window select the Channel to be displayed. Only one channel may be viewed at a time. This screen includes a good deal of information. The voltage and current harmonics are presented graphically in the upper part of the window. The ordinate (y-axis) is scaled in percent of the fundamental. The abscissa (x-axis) is the harmonic. Both even and odd harmonics are shown.

The actual value of the voltage and current for each harmonic may be found in the Harmonic Values box. By clicking on the arrow buttons, higher or lower order harmonics may be selected. The Waveform Values box provides summary statistics for the overall current and voltage waveforms. This includes the RMS value, Total Harmonic Distortion (THD), Peak values, and Crest Factor.

Note: The individual harmonic values and THD can be shown as a percentage of the fundamental (IEEE Standard 1035-1989) or as a percentage of the total RMS value (CSA and IEC standard). The number of harmonics shown can be out to the 64th place plus the DC component.

Note: The image displayed shows a highly distorted (current) waveform from a computer power supply. These waveforms are typical for switching power supplies and are a major cause of line harmonics.