Glossary Updates12 new terms added to the glossaries · October 2, 2026, 22:44 CEST
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Glossary · Energy and utilities automation

Power quality

Also known as: Voltage quality, Electrical power quality

German: Spannungsqualität

In electrical engineering, power quality describes the characteristics of the voltage, and often the current, at a given point in an electrical system compared with reference values, including frequency, magnitude, dips and swells, interruptions, harmonics, unbalance and flicker. IEC 61000-4-30 defines measurement methods for power quality parameters.

  • Energy

In one sentence

Power quality describes how voltage and current at a point compare with reference values, covering dips, interruptions, harmonics, unbalance and flicker.

Example

A power quality analyzer records voltage dips from the grid that coincide with unexplained stops of a drive, which then gets ride-through settings.

How it applies

  • Engineering: Equipment must tolerate the expected voltage conditions and must not emit excessive disturbances; frequency converters, for example, produce harmonic currents that may need filtering.
  • Operation: Poor power quality can cause unexpected stops, resets, overheating and premature aging of components.
  • Diagnosis: Power quality measurements help explain intermittent faults that controller diagnostics cannot, making them part of Fault diagnosis for sporadic stops.
  • Documentation: Machine documentation should state the supply requirements (voltage tolerance, frequency, permitted harmonic distortion if relevant) and the machine's behavior on voltage dips and interruptions, including restart behavior. In Europe, EN 50160 describes voltage characteristics of public networks.

Power quality vs. power factor

Power factor is one single quantity describing the relation between active and apparent power. Power quality is the broader set of voltage and current characteristics; harmonics affect both.

By knowledge.aitechdoc.world · Published September 26, 2026 · Last reviewed

Source: IEC 61000-4-30, Electromagnetic compatibility (EMC) — Part 4-30: Testing and measurement techniques — Power quality measurement methods

Definitions follow the cited standards and specifications. Where a source is a copyrighted publication, such as an ISO, IEC or EN standard, the definition is a close paraphrase, not a verbatim quotation, so as not to infringe copyright. We recommend reading the original publication. The sections “How it applies” are editorial commentary by AI TechDoc Blog and are not part of any standard.

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