Line frequency is the most tightly controlled parameter in the electrical distribution system. Since almost all generation in a region is connected essentially in parallel, the frequency is inherently synchronized…
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Power Quality
Daily Profile Graphs in ProVision
Daily Profiles are used to spot daily trends in voltage, current, power factor, etc. An entire recording session is combined to form the "average" 24-hour day, which is then plotted…
Arithmetic vs. Vector Power
The basic formulas for RMS voltage, current, power, etc. in a simple single-phase circuit are well-defined and universal. For polyphase systems, the situation is more complex: in the 3-phase delta…
Measuring Voltage Unbalance
Voltage unbalance can cause severe heating in motors and large DC power converters and an increase in harmonic currents. Fortunately unbalance is easy to measure with PMI recorders and ProVision…
Computing Event Duration with Histogram Data
The cycle histogram is an important, but underused record type available with all PMI recorders. The histogram doesn't require any configuration, spans the entire recording session (no possibility of memory…
Optimizing Waveform Capture Triggering
Waveform capture is the highest resolution data available for PQ analysis and is often crucial in solving tricky issues. Successfully triggering on the waveform doesn't have to be tricky, though.…
Harmonics from Periodic Waveform Capture
Harmonics are usually recorded as interval (stripchart) data in PMI recorders. Each desired harmonic is recorded as a min/ave/max stripchart trace, for each desired voltage and current channel. Although this…
Identifying Loose Neutrals
This white paper describes what a loose neutral is, what effects it can have on electrical equipment, its causes, and some ways to easily detect if a loose neutral is…
Analyzing K Factor
K Factor is a measurement of current harmonic distortion that is used to de-rate transformers for harmonics. This white paper will discuss how K Factor is calculated, what its uses…
Transient Capture with the Vision and Revolution
Capture high-speed, high-voltage transients with the Revolution and Vision, using the optional transient capture system. Transient capture uses 1 MHz sampling for voltage, giving a 1 microsecond sample window, and…
Application of the GE Flicker Curve
This an overview of what the GE Flicker Curve is, how, why and when it was developed, and who developed it. Also, this paper covers some of the more useful…
Case Study: Ground Fault Detection
The main breaker tripped in a Motor Control Center. All circuits were meggered and checked out, but no cause was found for the trip. Because none of the load breakers…
