SUBSTATION
Substation
may be defined as the equipment or an assembly of equipment, which changes one
or more characteristics of the supply example power factor, frequency etc.
GENRAL CLASSIFICATION OF SUBSTATION
Step
– Up or primary substations
Step-down
or secondary sub-stations
Distribution
substations
Primary
Grid substations
SUBSTATIONS BASED ON DESIGN
1.
Indoor substations: Apparatus are installed within the substations.
2.
Outdoor substations: These substations are erected for distribution of power in
localities and are further classified as pole mounted substations and
foundation mounted substations.
BASED ON OPERATING VOLTAGES
High
Voltage substations – 11 kV and 66 kV
Extra
High Voltage substations – 132 kV and 400 kV
Ultra-High
Voltage substations – above 400kV
TYPES
OF SUBSTATIONS
01.
SWITCHING SUBSTATIONS
Switching
substation means for switching operation of power lines without transforming
voltage level to another level as per needs.
02.
GRID SUBSTATIONS
These
are the substations from where bulk power is transmitted from one point to
another point in the grid. These are important because any disturbance in these
substations may cause the failure of grid.
03.
CONVERTING SUBSTATIONS
These
substations converting AC to DC or vice-versa and converting frequency form
higher to lower or vice-versa.
03.
FREQUENCY CHANGING SUB-STATION
There
are many industrial applications for which frequencies lower or higher than the
frequencies of normal supply are needed. High frequency heating and dielectric
heating are examples. The substations which are installed for this particular
purpose are called frequency changing substations.
05.
POWER FACTOR CORRECTION SUBSTATION
Substations
which are used to correct or improve the power factor are known as power factor
correction substation. Generally synchronous motors are used for this purpose.
Therefore, they are also called synchronous sub-stations.
06.
MOBILE SUBSTATIONS
Mobile
substations needed for temporary requirements such as for construction
purposes. It requires special purpose and designs.
07.
CINEMATOGRAPHY SUBSTATIONS
The
cinematography substations are special purpose substations and are required to
meet the special requirements.
08.
MINING SUBSTATIONS
Mining
substations as the name indicates are substations required for special purposes
they need special design considerations, because of the extra for safety needed
in the operation of the electric supply.
09.
TOWN SUBSTATIONS
These
substations step – down the voltage at 33 / 11 KV for further distribution in
the towns and any failure in such substations results in the failure of supply
for whole of the town.
MAJOR EQUIPMENTS IN SS
1.
TRANSFORMER
Step
up and step down the voltage.
2.
BUS BAR
A
bus bar (sometimes pronounced "buzz bars") in electrical power
distribution refers to thick strips of copper or aluminium that conduct
electricity within a switchboard, distribution board, substation, or other
electrical apparatus. The size of the
bus bar is important in determining the maximum amount of current that can be
safely carried.
3.
ISOLATORS
Isolators
or disconnect switches operate under no load condition. They are not equipped
with arc-quenching devices.
4.
SWITCHES
1.
OIL SWITCH - The
oil switch has both the blade and the contact mounted in a oil-filled tank. The
switch is usually operated from a handle outside of the case. As the switch is
opens, the arc formed between the blade and contact is quenched by the oil.
2.
AIR-BREAK SWITCH – The
air-break switch has both the blade and the contact equipped with arcing horns.
[Arcing horns are piece of metal between which the arc resulting from opening a
circuit carrying current is allowed to form]
5.
CIRCUIT BREAKER
The
circuit breaker (CB) which normally gets signal from protective relays to
operate, is an automatic switch which can interrupt the fault current.
6.
FUSES & RELAYS
FUSE
- A
fuse is a short piece of metal, inserted in the circuit, which melts when
excessive current flows through it and thus breaks the circuit.
RELAY
- Relay
is device which senses abnormal conditions on a power system by constantly
monitoring electrical quantities of the system, which differ under normal and
abnormal conditions.
7.
CONTROL BOARDS and 8. CONTROL ROOM
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