ZyXEL Communications PLA-470 V2 - V3.0.5 Instalační příručka stáhnout pdf (Strana 163)

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Some types of meters integrating a galvanic isolation also behave as PLC signal

cutters. However, these models are relatively rare and most meters allow the

PLC signal to pass.

In both cases, it may be useful to override these devices to allow the PLC signal

to extend over the entire electrical network.

Transformers

Since transformers are inherently electrical devices ensuring a physical isolation

between two electrical circuits with a different voltage, they cannot be used to con-

vey the PLC signal between the two parts of the network. In this case, it is necessary

to add a PLC device to the transformer; this device is used to retrieve the PLC signal

from one side of the transformer and to reinject it on the other side by re-amplifying

it so that the signal travels all over the LV electrical network up to the PLC modem

of the end user.

Figure 7.27 illustrates the transformer overriding principle with the various PLC

signal injection points and the PLC modem of the end user located behind the meter.

A PLC device used to override a transformer can only be installed by teams

accredited by the electrical network operator. This is because it is necessary to have

access to the MV/LV (medium voltage to low voltage) transformer vault.

Meters

Meters are used to measure the electrical consumption of a house and to invoice the

users of the electrical network or of another state-owned electrical company. These

144 Equipment

Figure 7.27 Transformer overriding

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ZyXEL Communications PLA-470 V2 - V3.0.5 Instalační příručka Strana 163