When lights start flickering,voltage
fluctuations are already happening
Voltage flicker remains one of the most frequent power quality complaints reported by utility customers. While the visible symptom is changing light intensity, the underlying cause is usually rapid voltage fluctuations produced by equipment such as arc furnaces, motor starts, welders, or modern power electronics.
Accurately evaluating flicker requires standardized measurement techniques and careful interpretation of the resulting data. Modern power quality monitors now implement the flickermeter defined in IEC 61000-4-15 and adopted by IEEE 1453, producing metrics such as Instantaneous Flicker Level, Short-Term Flicker Severity (Pst), and Long-Term Flicker Severity (Plt).
This white paper explains how flicker is measured, how utilities analyze flicker recordings, and how modern tools like PQ Canvass and Merlin™ assist engineers in diagnosing flicker issues more efficiently.
Key topics covered:
- Overview of Flicker
- Flickermeter Defined
- How does the Flickermeter Work?
- Data Collection and Analysis Using PQ Canvass
- Flicker Limits
- Automated Flicker Diagnosis Using Merlin™
Why utilities should care:
Customer flicker complaints often require careful analysis before the cause can be confirmed. Utilities must determine whether the issue originates from load behavior, system conditions, or equipment interactions. Understanding how flicker is measured and how to interpret metrics such as Pst and Plt allows engineers to evaluate complaints using standardized methods and defensible data. This paper walks through the fundamentals of flicker measurement and shows how tools like PQ Canvass® and Merlin™ can assist engineers in reviewing recordings, comparing results to accepted limits, and identifying sources of voltage fluctuations during real power quality investigations.
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