While three-phase AC squirrel-cage motors have been around and reliable since 1889, courtesy of Mikhail Dolivo-Dobrovolsky, one issue that has plagued their operation and lifespan throughout the years has been…
White Papers
Browse our library of power quality technical resources.
14 results in Voltage Unbalance — Clear
Voltage Unbalance
Voltage Regulation: Standards-based Compliance
Voltage regulation—the ability to maintain steady‑state RMS voltage within acceptable bounds—affects equipment performance, protection, and customer experience. Distributed energy resources (DER) add complexity via bidirectional power flow and daytime voltage…
Voltage Unbalance Within PQ Canvass Compliance Reports
Power Monitors, Inc.'s PQ Canvass is a secure, cloud-based platform built for power-quality (PQ) analysis. PQ Canvass has a beta feature of automated "compliance reports" that transform data uploaded from…
Voltage Tug-of-War The Silent VFD Killer
The modern variable-speed drive (VFD) is a sophisticated power electronic system, yet the front end is still a deceptively simple six-pulse diode bridge. That simplicity means the rectifier has little…
Why You Should Transition ProVision to PQ Canvass
Introduction If you own a Power Monitor’s recorder you’re probably quite familiar with ProVision. If you aren’t, it’s Power Monitors’ Windows desktop application that lets you manage your PMI recorders,…
Phasor Decomposition via Symmetrical Components in Three Phase Systems
Introduction When three phase systems are perfectly balanced sinusoidal waveforms, where the B and C phases are exact replicas of the A phase sine wave, but delayed by 120 and…
Voltage Imbalance and Its Impact on Waveform Distortion
Voltage imbalance, also referred to as voltage unbalance, is an important power quality issue that can lead to significant operational problems in customer equipment. It occurs when the magnitudes or…
Understanding IEEE 1159 Definitions
It is very important to have recommended guidelines and practices in place regarding power quality monitoring with the use of consistent terminology and definitions of power quality phenomena. This is…
Adjusting Waveform Capture Sampling Rates
Waveform capture is one of the most important data types available for PQ analysis. The sample-level data provides detailed information for voltage disturbances such as oscillatory transients, notches, sub-cycle overvoltages…
Four-Wire Delta Voltage Unbalance
Voltage unbalance in a four-wire or "high leg" delta can be tricky to measure. A 4-wire delta often involves unbalanced impedances, and phase shifts in the hot leg are common.…
Hidden Delta Voltage Unbalance
Voltage unbalance can cause severe heating in motors and large DC power converters. Although most voltage unbalance is caused by unequal loading among phases, shifts in voltage phase angle can…
Voltage Swell from Recloser Operation
A recloser is most associated with brief voltage interruptions, possibly followed by an extended outage if a fault cannot be cleared. Upstream customers experience voltage sag during the reclose attempts,…
