PARTICULAR NATURE´S ELECTRICITY

Electricity is a form of energy particularly flexible and adaptable. Can be converted into other forms of energy: heat, light, mechanical energy and in other ways: electromechanical, electronic, acoustic and visual techniques are based on modern telecommunications, information technology and entertainment.

Electricity, as supplied to customers, has several features that may vary and affect their usefulness to users of the network. This standard describes the characteristics of the AC voltage electricity. Given the use made of electricity, it is desirable that this alternating voltage supplied at a constant frequency, according to a perfect sine wave and a constant amplitude. In practice this does not allow many factors. Unlike standard products, the use made of it is one of the main factors determining the variation of its "features".

The power supply to equipment users in the network causes electrical currents roughly proportional to the demand of users. When these currents flow through the network drivers, give rise to voltage drops. The amplitude of the voltage supplied to a user at any time is a function of accumulated voltage drops across all network elements through which the user feeds, and is determined both by individual demand and the simultaneous demand from other users. Since each customer demand is constantly changing along with additional variation depending on the match between the demands of different users, also vary the voltage supplied. For this reason, this standard deals with the voltage characteristics in terms of statistics and probability. Economic benefit of the customer, the standard corresponds to normal conditions rather than under unusual circumstances such as an unusual degree of overlap between the demands of multiple devices or users.

The electricity reaches the customer through a system of production, transportation and distribution. Each network element can be subjected to damage or failure caused by electrical stresses, mechanical and chemical, due to various factors such as extreme weather conditions, normal wear, aging, external causes due to human activities, the birds , animals, etc.. Such damage can affect or even disrupt the power of one or more users.

To maintain constant frequency, it is necessary to have a production capacity in each time adapted to the demands of all users simultaneously. As the production capacity and the load likely to vary discretely, particularly in the case of failures in the generation and transmission or distribution, there is always a risk of imbalance that causes an increase or decrease the frequency. However, this risk is reduced if many networks are grouped in a large interconnected network whose production capacity is very large with respect to any changes which may occur.

Many other features can disrupt or damage the user's computers and even network user itself. Some of these characteristics are linked to unavoidable transients inherent to the network itself, caused by the misconduct, maneuvers or atmospheric phenomena (lightning). Other features, however, are the result of various uses of electricity directly modify the waveform voltage, impose a particular value of the amplitude or voltage signal superimposed information. Coincidentally, the recent proliferation of equipment which produces these effects is accompanied by an increase in the number of equipment sensitive to these disturbances.

This European Standard defines, when possible, the variations of the features normally expected. In other
cases, the standard gives a quantitative estimation, the best of what you find in practice.

Due to the diversity of structures of distribution networks in different regions resulting from the differences of charge density, dispersion of the population, local topography, etc.., Many users of the network can find variations the voltage characteristics well below the values ​​indicated in this statement.

One of the properties of electricity is that, with respect to some of its characteristics, its quality depends more on the user to the supplier or producer. In such cases, the user is thus an important partner of the supplier to strive to maintain quality of electricity.

It should be stressed that this issue has been addressed in other standards already published or under development: the emission standards of customer devices define levels of electromagnetic interference that these teams are authorized to issue. Immunity standards define levels of disturbance tolerated by the equipment without causing excessive damage or stop functioning. A third type of standards concerning electromagnetic compatibility levels can coordinate and harmonize standards of emission and immunity, in order to ensure electromagnetic compatibility.

Although there are obvious links with the levels of compatibility, it is important to note that this standard deals with the characteristics of the voltage. This is not a standard for compatibility levels. It is important to note that the performance of a team can degrade if feeding conditions are more severe than those defined in the relevant product standard.

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