The document provides an overview of a power substation (switchyard) including: - Typical components including busbars, circuit breakers, current transformers, and surge arrestors. - Explanations of switchyard equipment such as circuit breakers, isolators, earth switches, and their functions. - Descriptions of different types of substations based on voltage levels and mounting structures. - Brief explanations of additional equipment such as capacitive voltage transformers, wave traps, and post insulators.

1. SUBSTATION
(A GENERAL VIEW)
NAME-ASHWANI KUMAR
ROLL NO-124011

2. CONTENTS
 Abstract
 Substation and Its types
 Symbol For SwitchYard Equipment
 SwitchYard Equipment
 Protective Relays and Its types
 SwitchYard Emergencies and Plan Of
Actions.

3. ABSTRACT
 The power system network basically consists of three sub-
network - generation sub-network, transmission sub-
network, distribution sub-network.
 However due to any reason some fault occurs, these
conditions become abnormal by increase or decrease in
voltage , current & power factor becomes very high & poor or
line flows become abnormally very high- it is necessary that
there should be a device which senses these abnormal
conditions
 It is necessary to remove the abnormality because the power
system components can never be designed to withstand the
worst possible conditions, as it will make the whole system
highly uneconomical.

4. SUBSTATION
 Substations serve as sources of energy supply
for local areas of distribution in which these are
located
 Main function is to receive energy transmitted at
high voltage from generating stations, reduce the
voltage to a value appropriate for local
distribution and provide facilities for switching .
 It also provides points where safety devices may
be installed to disconnect equipment or circuit in
event of fault

5. TYPES
 HighVoltage Substation – It operates voltages
between 11KV and 66KV.
 Extra HighVoltage Substation – Involving
voltages between 132KV and 400KV.
 Ultra HighVoltage Substation – Operating on
voltage above 400KV.
 IndoorType Substation – Apparatus is installed
within substation building which are usually for
voltage upto 11KV, 33KV and 66KV.

6. TYPES (contd..)
 Outdoor Substation – Subdivide into –
i. Pole Mounted Substation – Useful for
distribution of power in localities. H-pole or 4
pole structure with suitable plateform is used for
transformers of capacity upto 250KVA.
ii. Foundation Mounted Substation – For
transformers of capacity above 250KVA.The
transformers are too haevy for pole mounting .
Such substation are usually for voltages of 33KV
and above .

7. Typical Components of a Power
Plant Substation (Switchyard)
•A - Busbar
•B - Disconnector
•C - Circuit Breaker
•D - Current Transformer
•E - Voltage Transformer
•F - Earthing Switch
•G - Surge Arrestor
• CONNECT
• CONNECT & DIS-CONNECT
• CONNECT, DIS-CONNECT & DETECT
• DETECT & TRANSFORM
• DETECT & TRANSFORM
• PROTECT & SAFETY
• PROTECT

8. SWITCHYARD EQUIPMENT
 Circuit Breakers
 Isolators
 EarthSwitch
 Bus bar
 Surge / Lightening Arrestors
 CurrentTransformer
 CapacitiveVoltageTransformer
 WaveTrap
 Post Insulator
 Relay

9. CIRCUIT BREAKER
 Circuit Breaker – it is an automatically operated electrical
switch designed to protect an elctrical circuit from damage caused by
overload or short circuit. Its basic function is to detect a fault condition
and interrupt current flow.
 The operation of the breaker is very rapid when opening.
 Working of circuit breaker- The circuit breaker mainly
consists of fixed contacts and moving contacts. In normal “on”
condition of circuit breaker, these two contacts are physically
connected to each other due to applied mechanical pressure on
the moving contacts. There is an arrangement stored potential
energy in the operating mechanism of circuit breaker which is
realized if switching signal given to the breaker. The potential
energy can be stored in the circuit breaker by different ways like
by deforming metal spring, by compressed air, or by hydrolic
pressure.

10. WORKING OF CIRCUIT
BREAKER(Contd…)
But whatever the source of potential energy, it must be released
during operation. Release of potential energy makes sliding of the
moving contact at extremely fast manner All circuit breaker have
operating coils (tripping coils and close coil), whenever these coils
are energized by switching pulse, the plunger inside them
displaced. This operating coil plunger is typically attached to
the operating mechanism of circuit breaker, as a result the
mechanically stored potential energy in the breaker mechanism is
released in forms of kinetic energy, which makes the moving
contact to move as these moving contacts mechanically attached
through a gear lever arrangement with the operating mechanism.
After a cycle of operation of circuit breaker the total stored
energy is released and hence the potential energy again stored in
the operating mechanism of circuit breaker by means of spring
charging motor or air compressor or by any other means.

11. 1. Actuator lever - used to manually trip
and reset the circuit breaker.
2. Actuator mechanism - forces the
contacts together or apart
3. Contacts - Allow current when
touching and break the current when
moved apart
4. Terminals
5. Bimetallic strip.
6. Calibration screw - allows the
manufacturer to precisely adjust the
trip current of the device after
assembly.
7. Solenoid
8. Arc divider/extinguisher
CIRCUIT BREAKER

12. TYPES OF CIRCUIT BREAKER
 Air Circuit Breaker-
 Arc is initiated and extinguished in substantially static air in
which the arc moves.
 Used for low voltages upto 15KV and rupturing capacities of
500MVA.
 Air Blast Circuit Breaker-
 Blast of air is used to blow out the arc.
 Air is stored in tank and released through a nozzle to produce
high velocity jet to extinguish the arc.

13. TYPES OF CIRCUIT
BREAKERS(Contd..)
 Sulphur Hexafluoride(SF6) Circuit Breaker –
 SF6 Under pressure is used to extinguish the arc.
 SF6 gas have excellent dielectric, arc quenching
,chemical and other physical properties and is superior
to other arc quenching mediums such as oil and air.
 Vaccum Circuit Breaker –
 Fixed and moving contacts are housed inside a
permanenly sealed vaccum interrupter .The arc is
quenched as contacts are separated in high vaccum .
 It is more efficient,less bulky, cheaper in cost and
longer life.

14. ISOLATOR
 Isolator is a mechanical switch which isolates a part of
circuit from system for safe maintenance works.
 It is a disconnection switch and to be operated on no
load.
 It is used to make sure that an electrical circuit can be
completely de-energized for service or maintenance.
 It provide electrical isolation of the equipment.
 isolators must be open after circuit breaker is open and
these must be closed before circuit breaker is closed
otherwise arc would be produced results in power loss.

15. ISOLATOR
ISOLATOR WHEN OPEN ISOLATOR WHEN CLOSED

16. EARTH SWITCH
 Earth switch is required
to discharge the trapped
charges on the line &
consists of vertical
break.
 Earth switch can only be
operated locally.

17. BUS BAR
 The flow of electrical
power between incoming
and outgoing circuits
takes place through the
bus bars.
 These are junction points
carrying huge power’
 These are copper rods or
thin walled tubes
operating at constant
voltage.

18. TYPES OF BUS BAR
 Types of Bus Bar Arrangement:
 Single Bus bar Arrangement
 Single Sectionalized Bus bar Scheme
 Main & transfer bus bar scheme
 Double Bus arrangement
 Double bus and transfer bus arrangement
 One and half breaker scheme

19. SURGE/LIGHTENIG ARRESTORS
 A lightning arrester is a
device used on electrical
power systems to protect
the insulation and
conductors of the system
from the damaging effects
of lightning.
 The typical lightning arrester
has a high-voltage terminal
and a ground terminal. When
a lightning surge travels
along the power line to the
arrester, the current from
the surge is diverted through
the arrestor, in most cases to
earth.

20. SURGE/LIGHTENIG ARRESTORS
 A Surge Arrestor is a
voltage-sensitive device
that it operates in principle,
as a non-linear resistor.
 If protection fails or is
absent, lightning that strikes
the electrical system
introduces thousands of
kilovolts that may damage
the transmission lines, and
can also cause severe
damage to transformers and
other electrical or electronic
devices.

21. CURRENT TRANSFORMERS
 Used for measuring high
value currents.
 Designed to provide a
current in its secondary coil
proportional to current
flowing in its primary coil.
 Primary winding consists of
very few turns.
 Secondary winding consists
of large no. of turns.
 Current to be measured is
passes through primary
winding.

22. Capacitive Voltage Transformer
 A capacitor voltage
transformer (CVT or
CCVT), is a transformer
used in power systems
to step down extra high
voltage signals and
provide a low voltage
signal, for metering or
operating a protective
relay.

23. Capacitive Voltage Transformer
Main applications of CVTs in HV
Networks
 Voltage Measuring:They
accurately transform
transmission voltages down to
useable levels for revenue
metering, protection and
control purposes
 Insulation:They guarantee the
insulation between HV network
and LV circuits ensuring safety
condition to control room
operators
 HFTransmissions:They can be
used for Power Line Carrier
(PLC) coupling.

24. WAVE TRAPS
 WaveTraps are used at sub-
stations using Power Line
Carrier Communication
(PLCC).
 PLCC is used to transmit
communication and control
information at a high
frequency over the power
lines.
 This reduces need for a
separate infra for
communication between
sub-stations.

25. WAVE TRAPS
 The WaveTraps extract the high
frequency information from the
power lines and route it to the
telecomm panels.They also
block any surges from passing
through.
 WaveTraps are simply resonant
circuits that produce a high
impedance against Power line
carrier communication carrier
frequencies (24kHz - 500kHz)
while allowing power frequency
(50Hz - 60Hz).

26. POST INSULATORS
 These provides necessary
insulation between line conductors
and supports and thus prevent the
leakage of current from
conductors to earth.
 Insulators used for high-voltage
power transmission are made
from glass, porcelain or composite
polymer materials.
 Porcelain insulators are made
from clay, quartz or alumina and fe
ldspar, and are covered with a
smooth glaze to shed water.

27. POST INSULATORS
 Types of insulator-
1. Pin type insulator - The pin type
insulator is mounted on a pin on
the cross-arm on the pole and
used for electric power at voltages
up to 33 kV.
2. Suspension type insulator- For
voltages greater than 33 kV, it is a
usual practice to use suspension
type insulators consisting of a
number of glass or porcelain discs
connected in series by metal links
in the form of a string.
3. Strain insulator.
4. Shackle insulator – For low
voltage levels .

28. How Substation Work

29. RELAYS
 Relay- It detects the faulty element in the integrated
power system and removes it with the help of circuit
breaker from the remaining healthy system as quickly
as possible to avoid the damage.
 Main features-
 Reliability .
 Sensitivity .
 Simplicity .
 Speed .
 Economy .

30. TYPES OF RELAYS
 OVERVOLTAGE, OVERCURRENT AND
OVERPOWER RELAYS-These relays operate
when the voltage,current and power rises above
a specified value .
 UNDERVOLTAGE,UNDERCURRENT AND
UNDERPOWER RELAYS-These relays operate
when the voltage, current and power falls below
a specified value .
 DISTANCE RELAY-In this relay, the operation
depends upon the ratio of voltage to current .

31. TYPES OF RELAYS(Contd…)
DIRECTIONAL OR REVERSE CURRENT
RELAY –The relay operates when the applied
current assumes a specified phase
displacement with respect to applied voltage
and relay is compensated for fall in voltage.
DIRECTIONAL OR REVERSE POWER
RELAY- It operates when the applied current
and voltage assumes specified phase
displacement and no compensation is allowed
for fall in voltage.

32. TYPES OF RELAYS(Contd…)
DIFFERENTIAL RELAY –This relay operates
when some specified phase or magnitude
difference between two or more electrical
quantities occurs.

33. Switchyard emergencies & Plan of
action :
Condition Monitoring
Breakdown Analysis
Annunciations & Alarm schemes:
 Circuit breaker condition monitoring annunciations
 Alarms related to transmission line & feeder
protection
 Alarms related to transformer protection

34. De-Energisation & Isolation of
Switchyard Equipment :
When some abnormality observed in a section
of the system, the faulty section should be
isolated from the main system to safe guard
the rest of the system.
When the equipment found defective while in
service, isolation of defective equipment or
section is necessary to stop further damage
to that equipment or surrounding equipment.

35. THANK
YOU