ZyXEL Communications PLA-470 V2 - V3.0.5 Przewodnik Instalacji Pobierz pdf (Strona 43)

With the exception of EMTP, which allows modeling an entire electrical net-

work and all its wiring as a function of its topology, there exist few tools capable of

facilitating the engineering and the understanding of the behavior of PLC signals on

electrical wiring.

However, Cenélec (the European Committee for Electrotechnical Standardiza-

tion) is developing a system to facilitate the modeling of in-home electrical

networks.

Architecture with a Shared Medium

Chapters 10, 11, and 12 are devoted to the installation of PLC networks for homes,

businesses, and communities. We will see that the topology of electrical networks

can be viewed as a medium shared by all equipment carrying multiple PLC signals,

transporting data exchanged between terminals of a local network.

In those chapters, we will distinguish “public” networks, which furnish electric-

ity to individuals, businesses, and communities, and “private” networks, composed

of the electrical distribution network of a building, from the meters to the outlets.

We will see that the notion of a shared medium is equivalent to these two types of

networks.

Public Networks

A public electrical network is a distribution network that supplies houses, apart-

ments, buildings and businesses within a neighborhood, a town, or a community.

This network is public to the extent that anyone may become a subscriber and be

supplied by the local electrical authorities.

Figure 2.6 illustrates schematically a public electrical network supplying six

meters, behind which we find PLC devices connected to the home’s private electrical

network. The medium is shared among the meters, according to the topology of the

public electrical network (star, ring, and so forth) and its branches.

In this Figure, two electrical branches terminate at several meters and at PLC

equipment. The PLC signal propagates between the various devices connected to the

electrical network along these branches, including the sets of meter and circuit

breakers. A related issue is the signal attenuation along the electrical wiring. We can

thereby visualize the electrical network as a data bus, with PLC devices connected

on both the public and private zones.

Private Networks

A private electrical network is located behind the meter connecting it to the public

electrical network and is managed by those in the zone it serves: an apartment, a

house, an office, a factory, and so forth.

The topology of this type of network, unlike that of public electrical networks,

does not follow well-defined engineering rules and may be installation-specific

(addition of parts of a network or circuit breaker panels, series topology, and so

forth). Nevertheless, all branches of the network generally stem from the meter and

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ZyXEL Communications PLA-470 V2 - V3.0.5 Przewodnik Instalacji Strona 43