POWER QUALITY METERS AND ANALYZERS BASIC INFORMATION

What Are The Uses Of Power Quality Meter and Analyzers?

A number of manufacturers make “power-quality meters” and “power quality analyzers,” which are instruments similar to oscilloscopes, but that have a number of functions particularly suited to making power-quality measurements.

In measuring power quality, we must be able to trigger on events that are not continuous (such as a voltage sag) or transient (like that caused by lightning strikes or utility faults). For instance, typical power quality meters/ analyzers and analyzers have the following functionalities:

■ Data logging—capturing waveforms in real-time for later display

■ The ability to trigger on power-quality events such as sags, swells, or transients

■ Calculation of power-quality metrics such as total harmonic distortion in real-time

■ Spectrum analysis

■ Inputs for high-voltage probes and high-current probes. Numerous factors should be considered when selecting a power quality measurement meter/analyzer, including:

■ The number of channels (for instance, single-phase or three-phase)

■ The input voltage range

■ The current measurement range

■ Isolation

■ Communication capabilities (For example, can the instrument be networked or tied to a stand-alone computer?)

The power-quality analyzer A/D converts system voltages and currents. Power indices such as THD, harmonic content, and the like are calculated in real-time. In addition, the analyzer has on-board memory so data may be saved for future analysis.

In the output of a typical power-quality analyzer we see the time waveform of the line current in a copy machine and the harmonics.