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.
