It's a full fledged presentation about visit to a substation. It's about when we visited the 400 kV substation situated at Hadala, Rajkot, Gujarat, India. It includes almost aa details about it. Juz go for it!!!

1. Visit to 400 kV substation
Created by
- NANDAN DESAI

2. Location : Hadala, Rajkot, Gujarat

3. Location : Hadala, Rajkot, Gujarat

4. ABOUT THE SUBSTATION
 The substation at Hadala (Rajkot), Gujarat is a 400 kV distribution substation.
 It receives power at 400 kV from Adani Thermal power plant via Varsana, from Mundra
TPP via Chorania (Limbdi) and via Jetpur and from Varsana SS.
 It sends power at two voltage levels – 220 kV and 132 kV to Morbi, Nyara (Rajkot),
Tappar, Gondal etc.
 The substation is connected as a ring system as
Chorania
(Limbdi)
Amreli
Jetpur
Hadala
(Rajkot)
(Continue… )

5. (cont.)
 The substation is having two main bus and one transfer bus for both 400 kV side and
220 kV side.
 There are in total 6 lines of 400 kV level, 8+ lines of 220 kV and some lines of 132 kV
level.
 It’s a record that there has been no accidents in this substation since last 2000+ days.

6. Equipments in substation
 Lightening arresters
 Wave trap
 Current Transformer (C.T.)
 Potential Transformer (P.T.)
 Line isolator with Earthing switch
 SF6 Circuit breaker with starting
resistance
 Bus isolator
 3 phase reactor
(cont.)

7. Equipments in substation
 Power transformers
 Cables trench & tray
 Fire fighting facility

8. LIGHTENING ARRESTER
 The lightening arresters (L.A.) are used to ground
the high voltage impulse falling on line during
lightening.
 L.A. of all the lines connected to a bus are
connected in parallel in order to ensure the proper
grounding of surge as well as to increase its life.
 The L.A. core is made up of Zinc Oxide (ZnO2). It
acts as a non-linear resistance i.e. it offers a very
high resistance during normal conditions and offers
low resistance to the surge voltages.
 A ring type structure is attached to L.A. in order to
reduce the corona effect.

9. WAVE TRAP
 A wave trap is used on those transmission
lines which are equipped with PLCC (Power
Line Carrier Communication).
 As the communication signal frequency is
much different from line frequency and also
the voltage level is too low, it is quite
necessary to separate the power signal and
communication signal.
 This task is performed by a wave trap which
simply consists of L-C series and parallel
filters.

10. INSTRUMENT TRANFORMERS
 The instrument transformers are:
1. Current Transformers (C.T.) – Used to
measure phase current.
2. Potential Transformers (P.T.) – Used to
measure phase to neutral voltage.
 In this substation at some places CVT
(Capacitive Voltage Transformers) are
used which does function of PT as well as
assisting the Wave Trap.
C.T. P.T.

11. LINE/BUS ISOLATORS
Centre Break
Isolator
Double Break
Isolator
Pantograph type bus isolators

12. LINE/BUS ISOLATORS
 The line isolators are used to isolate the line (after the operation of opening C.B.)
under maintenance from the healthy system which otherwise may get resulted in L-
G fault.
 The bus isolators are used to isolate the bus under maintenance.
 In this substation normally line isolators were centre break type isolators while the
bus isolators were either double break type OR pantograph type isolators.
 The disc type structure at the tips of centre break type isolator is to reduce the
corona loss while they are open.
(cont.)

13. CIRCUIT BREAKERS
 In this substation almost all the circuit
breakers are SF6 type circuit breakers.
 There is a switchable series resistance along
with the C.B. as shown here. It is inserted
while closing the circuit breakers for a short
time.
 This resistor, hence, limits the charging
current of the line’s stray capacitance.

14. 3 PHASE REACTOR
 The shunt reactors are used to absorb the excess of
reactive power in the transmission lines.
 In this substation as long transmission lines are
terminating in, their stray capacitance inject reactive
power to absorb which, the reactor is installed here.
 The installed reactor is capable to reduce the line
voltage by as much as 5 kV.
 In this substation, power lines coming from wind
power station is also terminating. Since, there are
large variations in the power production, their reactive
power demand is also varying. Hence the reactor here
is a switchable reactor.

15. POWER TRANSFORMER
 This substation has two type of power transformers:
1) 400 kV  220 kV and
2) 220 kV  132 kV
 The cooling system employed is forced air – forced oil.
 The cooling systems of transformers are automatically
controlled. Once the temperature reaches 70 C, the
cooling system starts and as temperature reaches 60  C,
the systems switches OFF.
 The supply to the cooling system is given from the
substation supply transformer.
400 kV transformer
220 kV to 132 kV transformer

16. CABLES TRENCH & TRAY
 The cables that collect the communication signals from
instrument transformers, circuit breakers, isolators,
wave traps etc. are made to run in cable trench
towards the control room.
 The place where all the cables are collected is called
cable tray.

17. FIRE FIGHTING FACILITY
 As oil is used as coolant and body insulator, there are possibilities of fire in case of
short circuits.
 Fire fighting facility available in two ways in this substation.
 One way is that at some particular distance gaseous fire extinguishing cylinders
are kept.
 Another is that a water pipe runs everywhere in substation. In case of fire, it
sprinkles the water in surrounding area in fine molecular form in order to stop
propagation of fire.

18. CONTROL ROOM & RELAY ROOM
• The control room has various control panels which shows the information like
incoming power, outgoing power, frequency, time common to all substations, status
of various lines (healthy, faulted, under outage or maintenance), status of various
protective instruments like isolators, circuit breakers; temperatures of various
instruments, working tap of transformers etc.
• The DAS (Data Acquisition System) is used to accumulate the data received from
various sources.
• The relay room is separate from the control room. All relays used here are numerical
and are either from Siemens OR ABB .
• The protection system is so fast that it can detect a fault within 30 ms and hence the
circuit breaker can be operated within as less as 80 ms.
• For 400 kV side C.B., one time auto reclosure is allowed in order to clear the
temporary faults automatically.

19. Control Room Relay Room

20. BATTERY ROOM
 The control panels and relays of the substation require DC supply of 220 V.
 This DC supply is made with the help of battery bank reserve normally kept in a
separate room called Battery room.
 The batteries used in this substation are Nickel-Cadmium (Ni-Cd) batteries. These
batteries are used due to their advantages like low maintenance, longer life (15-25
years) etc.
 Each cell is of 2 V and 6Ah capacity.
 The battery room and the battery chargers are shown in next slide.

21. BATTERY ROOM & ITS CHARGERS
Battery Room Battery Chargers