Substation structures

Presented by

Jebitta P (1325007)

Adithyaa V (1325006)

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

MAIN COMPONENTS

TRANSFORMERCIRCUIT BREAKER

LIGHTING ARRESTERCURRENT TRANSFORMER

BUS BAR ISOLATOR

POTENTIAL TRANSFORMER WAVE TRAP

INSULATOR EARTH SWITCH

EARTHING SYSTEMCONTROL PANEL

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.