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Roger OTT: Senior Engineer, EDF Research and Development
INTRODUCTION
with the collaboration of Jean MARTINON, engineer, EDF Research and Development
Most electrical appliances connected to the grid require a sinusoidal power supply – at 50 Hz in France. Under these conditions, so-called passive loads, such as heating resistors or capacitors, absorb a periodic 50 Hz sinusoidal current.
But some devices, most of which use power electronics, absorb a non-sinusoidal current. This current still has a frequency of 50 Hz, but it is distorted. When it crosses the network impedance, this current distorts the voltage. These disturbances are then propagated throughout the network.
These devices are said to be non-linear, producing harmonic currents and voltages.
This is known as harmonic distortion. In some cases, the network configuration can amplify harmonic distortion. In such cases, the presence of non-linear loads can lead to malfunctioning of other devices connected nearby.
This article is part of a series devoted to voltage quality in networks. The other articles deal with the following subjects:
- Introduction ;
- Hollows and short cuts ;
- Fluctuations and flicker ;
- Find out more.
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Voltage quality
Definition
Technical and economic aspects
In the introductory article , it is shown that equipment connected to a network must, on the one hand, not "emit too much" disturbance and, on the other hand, must not be "too sensitive" to this same disturbance. While simple to express, this dual concept is more difficult to implement in the field. Indeed, for a particular piece of equipment, reducing its emission of disturbance and/or...
Bibliography
References
Standardization
The most recent versions at the date of publication are quoted here. The latest published versions are available in the online catalogs of the standards organizations.
IEC standards and publications
- Electromagnetic compatibility (EMC) – Part 2-2: Environment – Compatibility levels for low-frequency conducted disturbances and signal transmission on public low-voltage supply networks. - CEI 61000-2-2...
Organizations
Commission électrotechnique internationale (CEI) http://www.iec.ch
Union internationale pour les applications de l'électricité (UIE) http://www.uie.org
Association française de normalisation (Afnor)...
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