Chapter A General rules of electrical installation design

B40
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B - Connection to the MV public
distribution network
Fig. B39 : Outdoor substations without enclosures
6 Constitution of
MV/LV distribution substations
Outdoor substations without enclosures (see Fig. B39)
These kinds of outdoor substation are common in some countries, based on
weatherproof equipment exposed to the elements.
These substations comprise a fenced area in which three or more concrete plinths
are installed for:
b A ring-main unit, or one or more switch-fuse or circuit-breaker unit(s)
b One or more transformer(s), and
b One or more LV distribution panel(s).
Pole mounted substations
Field of application
These substations are mainly used to supply isolated rural consumers from MV
overhead line distribution systems.
Constitution
In this type of substation, most often, the MV transformer protection is provided by
fuses.
Lightning arresters are provided, however, to protect the transformer and consumers
as shown in Figure B40.
General arrangement of equipment
As previously noted the location of the substation must allow easy access, not only
for personnel but for equipment handling (raising the transformer, for example) and
the manœuvring of heavy vehicles.
LV circuit breaker D1
Safety earth mat
Fig. B40 : Pole-mounted transformer substation
Schneider Electric - Electrical installation guide 2008
Lightning
arresters
Earthing conductor 25 mm 2 copper
Protective conductor cover