Chapter A General rules of electrical installation design

B - Connection to the MV public
distribution network
Walk-in Non walk-in Half buried
a - b -
Underground
Fig. B38 : The four designs according to IEC 62271-202
standard and two pictures [a] walk-in type MV/LV substation;
[b] half buried type MV/LV substation
6 Constitution of
MV/LV distribution substations
Materials for operation and safety
According to local safety rules, generally, the substation is provided with:
b Materials for assuring safe exploitation of the equipment including:
v Insulating stool and/or an insulating mat (rubber or synthetic)
v A pair of insulated gloves stored in an envelope provided for the purpose
v A voltage-detecting device for use on the MV equipment
v Earthing attachments (according to type of switchgear)
b Fire-extinguishing devices of the powder or CO2 type
b Warning signs, notices and safety alarms:
v On the external face of all access doors, a DANGER warning plaque and
prohibition of entry notice, together with instructions for first-aid care for victims of
electrical accidents.
6.3 Outdoor substations
Outdoor substation with prefabricated enclosures
A prefabricated MV/LV substation complying with IEC 62271-202 standard includes :
b equipement in accordance with IEC standards
b a type tested enclosure, which means during its design, it has undergone a battery
of tests (see Fig. B37):
v Degree of protection
v Functional tests
v Temperature class
v Non-flammable materials
v Mechanical resistance of the enclosure
v Sound level
v Insulation level
v Internal arc withstand
v Earthing circuit test
v Oil retention,…
Use of equipment conform
to IEC standards:
b Degree of protection
b Electromagnetic
compatibility
b Functional tests
b Temperature class
b Non-flammable
materials
Fig. B37 : Type tested substation according to IEC 62271-202 standard
Main benefits are :
b Safety:
v For public and operators thanks to a high reproducible quality level
b Cost effective:
v Manufactured, equipped and tested in the factory
b Delivery time
v Delivered ready to be connected.
IEC 62271-202 standard includes four main designs (see Fig. B38)
b Walk-in type substation :
v Operation protected from bad weather conditions
b Non walk-in substation
v Ground space savings, and outdoors operations
b Half buried substation
v Limited visual impact
b Underground substation
v Blends completely into the environment.
LV
Schneider Electric - Electrical installation guide 2008
MV
Earthing circuit test Oil retention
Mechanical resistance
of the enclosure:
b Sound level
b Insulation level
b Internal arcing
withstand
B39
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