A switchyard is a type of electrical substation that connects and disconnects transmission lines for different grid regions. It contains various high-voltage equipment operating at the same voltage level, including transmission lines, circuit breakers, transformers, capacitors, reactors, and arrestors. The key components allow monitoring of voltages and currents, protection of equipment from surges, reactive power compensation, and safe disconnection of faulty lines. Switchyards play an important role in the reliable and efficient operation of India's integrated power transmission grid.

1. Pranay Gupta
Electronics Hardware
Engineer

2. INDIAN GRID SYSTEM
North-
East
Region
Northern
Region
Eastern
Region
Southerionn
Region
Western
Region

3. STATES UNDER GRID REGION

4. SwitchYard
Definition-
It is switching station with incoming and outgoing
feeders but without the transformer. It is a type of
substation but incoming feeders and outgoing feeders
are of same voltage level. Some times, the out door
area of a substation where the circuit breakers are
located are also called switchyard of the substation
 A switchyard connects and disconnects lines on the
grid for various regions. The operations and
equipment are essentially all at the same voltage level.

5. SwitchYard Equipment
•Transmission conductor
•Lightning Arrester
•Capacitor Voltage
Transformer
•Wave Trap
•Earth Switch
•Isolator
•Line Reactor
•Current Transformer
•Circuit Breaker
•Bus Bar
• Post Bus Insulator
•Corona Ring
•Static VAr Compensator
•ICT

6. Transmission Conductor-
•Application : To provide conducting medium
and connecting substation.
Specification:
•Stranded wire is used for decreasing skin effect.
•Material Used: ACSR Moose
•Nominal Voltage: 400kv
•Max. Systemvoltage:420kv
Lightning Arrester
A Surge Arrestor is a voltage-sensitive device that it
operates in principle, as a non-liner resistor.
It is a protective device which conducts the high
voltage surges on the power systems to the ground.

7. ISOLATORS
 Isolator is an off load device
which is operated by remote
control or local.
 Isolators provided in switchyard
are central break type.
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.

8. 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. Wave traps
Wave traps are used for
communication purpose during
fault conditions.
Wave traps offer high impedance
path for high frequency signals &
low impedance path for power
frequency current.

9. POST INSULATORS
 These provides necessary
insulation between line
conductors and supports and
thus prevent the leakage of
current from conductors to
earth
Corona Ring
To distribute the electric field
gradient and lower its maximum
values below the corona
threshold preventing corona
discharge.

10. 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.
Capacitor Voltage
Transformer
 Also known as Potential transformer
Used to step down extra high
voltage signals and provide a low
voltage signal, for measurement or to
operate a protective relay.

11. TRANSFORMER
Used to step down /step up the voltage .
In switchyard it is used step down to
11kv from 440kv of bus bars.
Line Reactor
It is used under the light load
condition to compensate the
capacitive Var of long lines.

12. Static VAr Compensator(SVC)
 One of the FACTS devices.
 Used to stabilization of voltage of line .
 It provide and compensate the reactive power of line
under variation of load.
 Thyristor controlled device.
 Removes 5th and 7th harmonics of line.

13. CIRCUIT BREAKERS
 These are switching devices, design to close or
open an electrical circuit under normal or
abnormal conditions.
 It is on load device.
 For arc quenching medium SF6 used .
 Spring SF6 circuit breaker
 Hydraulic circuit breaker
 Pneumatic circuit breaker
Relay
Relay 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

14. KVL & KCL…???