Photovoltaic (PV) generation is electrically in parallel with the utility supply, and thus lowers the steady-state system impedance. The ideal result is a reduction in locally caused voltage sags as…
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Understanding Harmonic Power
Harmonic power is a complex and often misunderstood topic. This leads to misinterpretations, including using a harmonic power analysis when the measurements aren't physically meaningful. An overview of harmonic power…
CBEMA-ITIC Analysis with Stripcharts
The ITIC curve (formerly CBEMA) is a performance-oriented standard for electronic equipment manufacturers. The standard gives a method for classifying and plotting voltage events on a specially constructed graph that…
Recording for NEC 220 Compliance
Utility customers who are expanding operations or adding load must comply with National Electric Code Article 220 to determine if any electrical upgrades are needed. Many customers will ask the…
THD Waveform Capture Triggering
The simplest waveform capture triggering is based on RMS voltage or current changes. While sufficient for voltage sags, recloser operations, etc., more complex events such as cap bank switches, narrow…
Key Issues with DG/DER Monitoring
The dramatic increase in distributed generation (DG), distributed energy resources (DER), and net metering scenarios brings sweeping, unplanned changes to the grid model. Local generation is often unpredictable, and sudden…
Detecting Loose Neutrals with a Receptacle PQ Monitor
Loose/open neutrals can present a dangerous and even life-threatening situation in a residential service. The classic voltage symptoms suggesting this condition are one single-phase leg rising in voltage, the other…
Spotting Loose Neutrals with Waveform Capture
A "loose neutral" in a residential location can cause equipment damage and even a house fire. An open neutral may start as a high resistance connection that shows subtle signs…
A Simplified Approach to IEEE 519 Harmonics
IEEE 519-2014 specifies measurements, analysis methods, and limits for harmonic voltage and current. A full IEEE 519 study is a straightforward, but rigorous analysis that can require multiple recordings and…
Cybersecurity and Cell Communications with the Guardian, Revolution, & Boomerang
Cybersecurity is an important component for any electric utility network device. PMI devices such as the Cell Guardian, Revolution, and Boomerang (Figure 1) generate data from raw voltage and current…
Quantifying Residential Voltage Sags
Voltage sag complaints are one of the most common in residential applications. Despite complaints, many residential voltage sags are not actually troublesome, or caused by the utility. Quantifying sag events…
Catching VFD Failures
Variable Frequency Drives (VFDs) present unique challenges as both a source of PQ problems as well as being sensitive to incoming voltage quality. A frequent complaint with a troublesome VFD…