ELECTRICAL TRANSMISSION & SUBSTATION STRUCTURES CONFERENCE ...
Substation structures
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Transcript of Substation structures
WHAT IS A SUBSTATION ?
A substation is a part of an
electrical generation, trans
mission,
and distribution system.
Between the generating
station and consumer,
electric power may flow
through several substations
at different voltage levels.
What does a substation do?
Electricity is made at a very high, powerful
voltage. A substation safely changes the
electricity from very high voltage to lower voltage
we can use.
CLASSIFICATION
Transmission substation
Distribution substation
Converter substations
Switching substation
Classification by insulation
Classification by structure
Types of substations
Classification based on voltage levels
Classification based on Outdoor or Indoor : Outdoor
substation is under open sky. Indoor substation is inside a
building.
Classification based on configuration, e.g. :
a. Conventional air insulated outdoor substation
b. Gas Insulated Substation (GIS)
c. Composite substations having combination of the above two
Classification based on application
Step Up Substation : Associated with generating station as the generating voltage is
low.
Primary Grid Substation : Created at suitable load centre along Primary transmission
lines.
Secondary Substation : Along Secondary Transmission Line.
Distribution Substation : Created where the transmission line voltage is Step Down to
supply voltage.
Bulk supply and industrial substation : Similar to distribution sub-station but created
separately for each consumer.
Mining Substation: precaution for safety needed in the operation of electric supply.
Mobile Substation: Temporary requirement
SUBSTATION PARTS AND EQUIPMENTS
Outdoor Switchyard
Incoming Lines
Outgoing Lines
Bus bar
Transformers
Bus post insulator & string insulators
Substation Equipment such as Circuit-beakers, Isolators,
Earthing Switches, Surge Arresters, CTs, VTs, Neutral Grounding
equipment.
Station Earthing system comprising ground mat, risers, auxiliary
mat, earthing strips, earthing spikes & earth electrodes.
Overhead earth wire shielding against lightening strokes.
Galvanised steel structures for towers, gantries, equipment
supports.
Power cables
Control cables for protection and control
Roads, Railway track, cable trenches
Station illumination system
EARTHING SYSTEM
Station earthing System includes
Earth Mat and Earth electrodes
placed below ground level
Function earthing system is to provide
low resistance earthing for
discharging currents from the surge
arresters, overhead shielding,
earthing switches.
For equipment body earthing.
For safe touch potential and step
potential in substation.
EARTHING
The following steps, when put into practice, will ensure a reliable, safe and trouble-free substation grounding system:
Size conductors for anticipated faults
Use the right connections
Ground rod selection
Soil preparation
Grounding using building foundations
Grounding the substation fence
Special attention to operating points
Surge arrestors must be grounded properly
Grounding of cable trays
Temporary grounding of normally energized parts
Cabling
Depth of the trench 750 mm for cables up to 1.1KV
Depth of the trench 1200 mm for cables up to 1.1KV
Sand - covered with 150 mm
Width of the trench - 350 mm minimum
Loop –approximate -3 meter each side
Cable laying
Laying direct in ground
In pipes,
Closed or Open ducts,
Cable trays and
On surface of wall
BUILDING
Administrative building
Conference room etc.
Battery Room
Operator room
Check and change room
Adjacent maintenance room
ECC room
why do we have substations?
To cheaply transfer electricity.
Substations are a part of what we call essential infrastructure.