All in one upload for the electrical power system

2. ELECTRICAL POWER GENERATION (Thermal
power-KTPS)
CONTENTS
 INTRODUCTION
 WORKING PRINCIPLE
 GENERAL LAYOUT OF THERMAL POWER PLANT
 MAIN EQUIPMENTS
 WASTE GENERATED AND THEIR CONTROL
 ADVANTAGES AND DISADVANTAGES
 REFERANCES

3. INTRODUCTION
 A Thermal Power Plant converts the heat energy of
coal into electrical energy. Coal is burnt in a boiler
which converts water into steam. The expansion of
steam in turbine produces mechanical power which
drives the alternator coupled to the turbine.
Thermal power plants contribute maximum to
generation of power for any country.
 Thermal Power Plants constitute 75.43% of total
installed captive and non-captive power generation
India.
 In thermal power generating stations coal, oil,
natural gas etc. are employed as primary sources
of energy.

4. WORKING PRINCIPLE
 Firstly the water is taken to the boiler from a water
source. The boiler is heated with the help of coal.
 The increase in temperature helps in the
transformation of water into steam. The steam
generated in the boiler is sent through a steam
turbine.
 The turbine has blades that rotate when high
velocity steam flows across them. This rotation of
turbine blades is used to generate electricity.
 A generator is connected to the steam turbine.
When the turbine turns, electricity is generated and
given as output by the generator, when is then
supplied to the consumers through high-voltage
power lines.

5. GENERAL LAYOUT OF THERMAL
POWER PLANT

6. MAIN EQUIPMENTS
 Coal handling plant
 Pulverizing plant
 Boiler
 Turbine
 Condenser
 Cooling tower and ponds
 Feed water heater
 Economizer
 Air preheater

7. COAL HANDLING PLANT
 Coal is transported to power station by rail or road and
stored in coal storage plant and then pulverized.
 The function of coal handling plant is automatic feeding
of coal to the boiler furnace.
 A thermal power plant burns enormous amounts of coal.
 A 200MW plant may require around 2000 tons of coal
daily.

8. PULVERIZING PLANT
 In modern thermal power plant, coal is pulverized i.e.
ground to dust like size and carried to the furnace in a
stream of hot of hot air. Pulverizing is a means of
exposing a large surface area to the action of oxygen
and consequently helping combustion.
 Pulverizing process consists 3 stages classified as:
1. Feeding
2. Drying
3. Grinding

9. BOILER
 The function if boiler is to generate steam at
desired pressure and temperature by transferring
heat produced by burning of fuel in a furnace to
change water into steam.

10. TURBINE
 In thermal power plant generally 3 turbines are
used to increases the efficiency.
 High pressure turbine.
 Intermediate pressure turbine
 Low pressure turbine

11. CONDENSER
 The surface condenser is a shell and tube heat
exchanger where cooling water flows through
tubes and exhaust steam fed into the shell
surrounds the tubes. As a result, steam condense
outside the tubes.

12. COOLING TOWERS AND PONDS
 A condenser needs huge quantity of water to
condense the steam.
 Most plants use cooled cooling system where
warm water coming from condenser is cooled and
reused.
 Cooling tower is a steel or concrete hyperbolic
structure with the height of 150m.

13. FEED WATER HEATER
 Feed water heating improves overall plant
efficiency.
 Thermal stresses due to cold water entering the
boiler drum are avoided.,
 Quality of steam produced by the boiler is
increased.

14. ECONOMIZER
 Flue gases coming out of the boiler carry lot of
heat. An economizer extracts a part of this heat
from flue gases and uses it for heating feed water.
 Saving coal consumption and higher boiler
efficiency.

15. AIR PREHEATER
 The function of air preheaters is to preheater the air
before entering to the furnace by utilizing some of
the energy left in the flue gases before exhausting
them to the atmosphere.
 After flue gases leave economizer, some further
heat can be extracted from them and used to heat
incoming heat. Cooling of flue gases by 20˚C
increases the plant efficiency by 1%.

16. WASTE GENERATED AND THEIR
CONTROL
 ASH HANDLING PLANT
 WATER HANDLING PLANT

17. ASH HANDLING PLANT
 The ash from the boiler is collected in two forms-
 Bottom ash(slurry): It’s a waste which is dumped
into ash pond.
 Fly ash: Fly ash is separated from flue gases in
esp.

18. WATER HANDLING PLANT
 Water in Power Plant is used for:-
 Production of steam- for rotating turbine.
 Cooling Purpose- For cooling of various
equipment.
 Water is recycled and used for various purpose:
Raw Water -- For Cooling Purpose -- Steam --
Condenser -- Raw Water
 About 4 cubic meter water is lost/day/mw.

19. ADVANTAGES & DISADVANTAGES
ADVANTAGES DISADVANTAGES
 The fuel used is quite cheap.
 Less initial cost as compare to
other generating stations.
 It can be installed at any place
irrespective of the existence of
coal. The coal can be
transported to the site of plant
by rail or roads.
 It pollutes the atmosphere due
to producing large amount of
smoke and fumes.
 Higher maintenance cost and
operational cost.
 Huge requirement of water.

20. ADDITIONAL DATA OF KTPS
 KTPS Generating Capacity- 1260MW
 Generated Voltage at KTPS- 15.75KV
 Generator Cooling System- Hydrogen, Water
 No. of Generator Transformer at KTPS- 6
 Boiler Feed Pump per unit- 3
 Types of Circuit Breakers- 400KV SF6, 220KV Air
Blast, 220KV SF6, 132KV MOCB, 132KV SF6,
33KV SF6, 6.6KV MOCB, 6.6KV SF6, 6.6KV
Vacuum, 400V Air
 CB in switch yard- 400KV SF6/220KV
MOCB/220KV Air Blast /220KV SF6 /132KV
MOCB/132KV SF6

22. ELECTRICAL POWER TRANSMISSION (Subhash
Gram )
CONTENTS:
 INTRODUCTION
 SUBSTATION LAYOUT
 RECEIVING POWER
 ELECTRICAL EQUIPMENTS IN 220KV SUB-
STATION
i. LIGHTNING ARRESTOR
ii. CAPACITOR VOLTAGE TRANSFORMER (CVT)
iii. WAVE TRAP
iv. CURRENT TRANSFORMER
v. ISOLATOR
vi. BUS BAR
vii. CIRCUIT BREAKER
 SINGLE LINE DIAGRAM
 SPECIFICATION OF THE POWER

23. INTRODUCTION
 The Subhash Gram 220 KV Substation under West Bengal State
Electricity Transmission Company Limited (WBSETCL)
 This substation mainly gets power from the nearby 400 KV
Substation of Power Grid Corporation of India Limited (PGCIL).
 It receives power at 220 KV voltage level from the nearby 440 KV
PGCIL Substation and feeds it to Lakshmikantapur1,
Lakshmikantapur2, Kasba, and KLC 220 KV Substation. Then the
220 KV supply is stepped down to 132 KV and feeds to Kasba1,
Kasba2, Joka and Sonarpur 132 KV feeder. Then the 132 KV supply
is stepped down to 33KV and feeds to Madarhat and Baruipur. After
that, the 33 KV is stepped down to 0.4 KV and supplied for auxiliary
station service.
 The Substation is well equipped with modern devices. It has two
220/132KV 160 MVA Power transformers, two 132/33KV 31.5 MVA
Power transformers, two 33/0.4KV 630 KVA Station Service
transformers and two 33/0.4KV 100KVA Earthing cum Station
Service transformers. And also it has many Current Transformers
(CT), Potential Transformers (PT), Capacitor Voltage Transformers
(CVT), Wave Trap, Lightning Arrester, Central Break Isolators,
Pantograph Isolators and a lot of safety equipment.

24. SUBSTATION LAYOUT
 BAY ARRANGEMENT
 Subhash Gram 220 KV sub-station has three switchyards. Based on the
three different voltage levels.
 Every equipment in the substation are well earthed. There is a large
sheet made of metal conductor net bedded under the ground connected
with every earth conductors of substation equipment. It is further
connected with a low resistance metal plate (earth plate) which is buried
about 70 Ft. deep into the ground.

25. RECEIVING POWER
 Power is received in the substation through 2
PGCIL (Power Grid Corporation of India Limited)
feeders. The receiving end voltage is 220 KV.
Before they come in contact with other
equipment, the three phases has to pass through
lightning arresters.
 The typical lightning arrester has a high-voltage
terminal and a ground terminal. When a lightning
surge (or switching surge, which is very similar)
travels along the power line to the arrester, the
current from the surge is diverted through the
arrestor, in most cases to earth.

26. ELECTRICAL EQUIPMENTS IN 220KV SUB-
STATION-
LIGHTNING ARRESTOR
 Lightning arresters are protecting devices. It protects the
substation equipment from over voltage or surges in
transmission lines.
 After passing through the lightning arrester, one of the 3
phases passes through CVT i.e. Common Voltage
Transformers.

27. CAPACITOR VOLTAGE TRANSFORMER (CVT)
 A capacitor voltage transformer (CVT) is a transformer
used in power systems to step-down extra high voltage
signals and provide low voltage signals either for
measurement or to operate a protective relay. In its
most basic form the device consists of three parts: two
capacitors across which the voltage signal is split, an
inductive element used to tune the device to the supply
frequency and a transformer used to isolate and further
step-down the voltage for the instrumentation or
protective relay. The device has at least four terminals,
a high-voltage terminal for connection to the high
voltage signal, a ground terminal and at least one set of
secondary terminals for connection to the
instrumentation or protective relay.

28. WAVE TRAP
 Wave trap or line trap is basically a low pass filter circuit
used in substations.
 The function of this trap is to trap the unwanted waves
(high frequency communication signals). It is connected
to the main incoming feeder so that it can trap the
waves which may be dangerous to the instruments here
in the substation.
 After that, the feeder passes through current
transformers.

29. CURRENT TRANSFORMER
 Current transformers are basically step up transformers
basically used to steps down the current from 1600 or 800
amps to 1 amp so that it can be measured using sensitive low
rating devices.
 The main use of this transformer is Distance Protection,
Backup Protection, Measurement
 There are 2 types of current transformers in the substation.
One is live tank and the other is dead tank. In the live tank
transformer, the tank is directly connected with the feeder,
while in the dead tank type, the tank is insulated from the
feeder and connected to earth conductor.
 And according to turns ratio also, there are two types of CTs.
One is of 1600:1 rating and the other is of 800:1 rating.
 After current transformers, the feeders ends at the isolators.

30. ISOLATOR
 Isolators isolate the feeders from the main bus. The main difference
between circuit breaker and isolator is that circuit breaker is that
circuit breaker can make or break a circuit but isolator is to be used
only when the circuit is already open. It cannot break a closed
circuit.
 There are two different types of isolators used in the substation.
 Pantograph Isolator or Jumper
 Centre Break Isolator
 The isolators are generally operated with 3 phase induction motors
that can be controlled either individually or in gang operation mode.
They can also be operated remotely from the control room.
 It is to be remembered that, before operating the isolators, we
should ensure that the circuit is open. If not, then we first have to
break the circuit using circuit breakers then operate the isolators.

31. BUS BAR
 There are 2 main bus and a transfer bus in the 220 KV
side. Each main bus is designed to take the full load
without any fault.

32. CIRCUIT BREAKER
 Circuit breakers are used to make or break the circuit in
high voltage lines
 Circuit breakers are also used for protection purposes.
Whenever they sense any dangerous over current, over
voltage, earth leakage etc. faults, they break the circuit
immediately. They can be operated remotely from the
control room. The insulation used in the circuit breaker
should be very high in terms to avoid breakdown of the
medium. This is why the circuit breakers used in the
Subhash Gram substation are gas insulated (SF6).
They provide better reliability than oil insulated CBs.
The best insulation property can be provided by
vacuum circuit breakers. But they are very expensive
and also difficult to maintain.

33. SINGLE LINE DIAGRAM

34. SPECIFICATION OF THE POWER
TRANSFORMER
 160MVA TRANSFORMER-
TYPE : Auto Transformer
TYPE OF COOLING : ONAN ONAF OFAF
RATED VOLTAGE : HV- 220KV
: IV- 132KV
: LV- 33KV
RATED CURRENT : HV- 252.32A
: IV- 420.39A
: LV- 472.94A
VECTOR GROUP : YNA0D11
MAX TEMP RISE : OIL- 50˚C
: WDG- 55˚C
FREQUENCY : 50Hz
PHASE : 3
TOTAL MASS : 90000 KG

35.  31.5MVA TRANSFORMER-
TYPE : Double Wound
TYPE OF COOLING : ONAN ONAF
RATED VOLTAGE : HV- 132KV
: LV- 33KV
RATED CURRENT : HV- 89.7A
: LV- 358.6A
VECTOR GROUP : Ynd1
MAX TEMP RISE : OIL- 50˚C
: WDG- 55˚C
FREQUENCY : 50Hz
PHASE : 3
TOTAL MASS : 61700 KG

37. ELECTRICAL POWER DISTRIBUTTION
(Baruipur)
CONTENTS:
• INTRODUCTION
• ELECTRICAL EQUIPMENTS IN 33/11KV SUB-
STATION
i. BUS
ii. INSULATOR
iii. CONDUCTOR
iv. ISOLATING SWITCH
v. CIRCUIT BREAKER
vi. PROTECTION RELAY
vii. INSTRUMENT TRANSFORMER
viii. DISTRIBUTION TRANSFORMER
ix. POWER TRANSFORMER
x. LIGHTNING ARRESTOR
xi. CAPACITOR BANK
xii. DC SYSTEM
• SINGLE LINE DIAGRAM
• SPECIFICATION OF THE TRANSFORMER

38. INTRODUCTION
 Electricity generates at generating station, and then it is
transmitted through step-up substation and primary
substation. Now Distribution system comes into the
picture. After primary grid, via secondary grid substation
and pole mounted substation, electricity reaches to
consumers end.
 In a substation various transformers are mounted for
step-up and step-down process. Substation plays a
most important part in the distribution system. The high
voltage transmission grid system links the generator to
the substation, which supplies power to the user
through distribution system. Interruption in these
connections links can disrupts the flow of power from
generator to user.
 In West Bengal, WBSEDCL is a govt. undertaking main
power distribution utility in a vast area in West Bengal.

39. ELECTRICAL EQUIPMENTS IN 33/11KV SUB-
STATION-
BUS
 When a number of lines operating at the same voltage have
to be directly connected electrically, bus bar are used. It is
made up of copper or aluminum bars and operate at a
constant voltage. There may be double lines in the bus so
that if any fault occurs in the one other can still have the
current and supply will not in the others can still have the
current and the supply will not stop. So that one can work at
the time and the other works only if the first having any fault.

40. INSULATOR
 The insulators serve two purposes. They support the
conductor (or bus bar) and or confine the current to the
conductors. The most commonly used material for the
manufacture of insulator is porcelain. There are several
types of insulators (i.e. pin type, suspension type, disc type
etc.) and there used in substation will depend upon the
service requirement.
Suspension Type Pin Type Disk Type
Polymar Type

41. CONDUCTOR
 Conductors carry electrical power from sending end to the
receiving end station. When A.C flows through a conductor, the
current is non-uniformly distributed over the cross section in a
centre of the conductor. This effect becomes more pronounced
with in frequency. This phenomenon is called Skin Effect. This
causes a large power loss in the A.C transmission. To minimise
this effect stranded conductors are used which have added
advantages of flexibility. Aluminium Conductor Steel
Reinforced (ACSR) is most commonly used in overhead
transmission lines. Aluminium is used because it is cheaper and
lighter than copper but with less conductivity and tensile
strength. To strengthen the conductor, it is steel reinforced. The
others conductors which are used are All Aluminium Alloy
Conductors (AAAC) and All Aluminium Conductors (AAC).Sl.
No.
CONDUCTOR ANIMAL
CODE
SPECIFICATION CROSS SECTION
AREA
Sq. mm
1 DOG CONDUCTOR Used in 33KV lines 100
2 RABBIT CONDUCTOR Used in 11KV Trunk lines 50
3 WEASEL CONDUCTOR Used in 11KV Branch lines 30
4 SQUIRREL CONDUCTOR Used in LT 3 phase lines and
single phase lines
20

42. ISOLATING SWITCH
 In substation, it is often desired to disconnect apart from
the system for general maintenance and repair. This is
accomplished by an isolating switch or isolators. An
isolator is essentially a knife switch and is designed to
often put a circuit under no load. In other words, isolator
switches operate only when the line is which they are
connected carry no load. For example, consider that the
isolator are connected on both the side of a circuit breaker,
if the isolators are to be opened, the Circuit Breaker must
be opened first.

43. CIRCUIT BREAKER
 The modern power system deals with huge power network and huge
numbers of associated electrical equipment’s. During short circuit
fault or any other types of electrical fault these equipment as well as
the power network suffer a high stress of fault current in them which
may damage the equipment and networks permanently. For saving
these equipment and the power networks the fault current should be
cleared from the system as quickly as possible. Again after the fault
is cleared, the system must come to its normal working condition as
soon as possible for supplying reliable quality power to the receiving
ends. In addition to that for proper controlling of power system,
different switching operations are required to be performed.
 So for timely disconnecting and reconnecting different parts of power
system network for protection and control, there must be some
special type of switching devices which can be operated safely
under huge current carrying condition. During interruption of huge
current, there would be large arcing in between switching contacts,
so care should be taken to quench these arcs in circuit breaker in
safe manner. The circuit breaker is the special device which does all
the required switching operations during current carrying condition.
This was the basic introduction to circuit breaker.

44. VACCUM CIRCUIT BREAKER
 A vacuum circuit breaker is such kind of circuit breaker where
the arc quenching takes place in vacuum. The technology is
suitable for mainly medium voltage application. For higher
voltage vacuum technology has been developed but not
commercially viable. The operation of opening and closing of
current carrying contacts and associated arc interruption take
place in a vacuum chamber in the breaker which is called
vacuum interrupter. The vacuum interrupter consists of a steel
arc chamber in the centre symmetrically arranged ceramic
insulators. The vacuum pressure inside a vacuum interrupter is
normally maintained at 10- 6 bar.
 The material used for current carrying contacts plays an
important role in the performance of the vacuum circuit breaker.
Cu/Cr is the most ideal material to make VCB contacts.

45. PROTECTION RELAY
 A relay is automatic device which senses an abnormal
condition of electrical circuit and closes its contacts. These
contacts in turns close and complete the circuit breaker trip
coil circuit hence make the circuit breaker tripped for
disconnecting the faulty portion of the electrical circuit from
rest of the healthy circuit.
 The value of voltage or current which is on threshold above
which the relay initiates to be operated.
 If the value of actuating quantity is increased, the
electromagnetic effect of the relay coil is increased and above
a certain level of actuating quantity the moving mechanism of
the relay just starts to move.

46. INSTRUMENT TRANSFORMER
 The lines in a substation operate at a very high voltage
and carry the current of thousands of amperes. The
measuring instruments are protective devices are
designed for low voltage (generally 11 KV) and current
about (5A). Therefore, they will not work satisfactory if
mounted directly on the power lines. This difficulty is
overcome by types of instrument transformer.
i. C.T (Current Transformer)
ii. P.T (Potential Transformer)

47. CURRENT TRUNSFORMER
 A current transformer is used in high voltage circuit to measure
the current flowing through the circuit. A current transformer is
used with its primary winding connected in series with line
carrying current to be measured. The primary winding consists
of a very few turns and there is no appreciable voltage drops
across it. The secondary winding of the current transformer has
larger number of turns, the exact number being determined by
its turn’s ratio. The ammeter or wattmeter current coil is
connected directly across the secondary terminals. Thus a
current transformer operates its secondary winding nearly under
short circuit conditions. One of the terminals of the secondary
winding is earthed so as to protect the equipment. Current
transformers are basically used to take reading of the current
entering the substation.

48. POTENTTIAL TRANSFORMER
 The Potential Transformer is used for measuring high
voltages by means of low range voltmeters or energizing
the potential coils of wattmeter and energy meter. These
are also used for energizing relay and other protecting
equipment's. The primary winding of the transformer is
connected across the line carrying the voltage to be
measured and the voltage circuit is connected across the
secondary winding. Potential transformers are employed
where ever and whenever the voltage of an AC circuit
exceeds the voltage of 750V.

49. DISTRIBUTION TRANSFORMER
 Transformers of rating up to 315KVA used to step down
the distribution voltage to a standard service voltage are
known as Distribution Transformers. They are kept in
operation all 24 hrs.
 they are designed for good all day efficiency and not for
the highest efficiency on full load. They are of self-cooling
type and are almost invariable oil immersed. The
distribution transformers are usually 3 phase 4 wire
11kv/400V delta star connected
 Now days WBSEDCL is using this types of transformer to
distribute power to the consumers. 315KVA, 250KVA,
160KVA, 100KVA, 63KVA, 25KVA, 16KVA, 10KVA.

50. POWER TRANSFORMER
 The term is used to include transformer of large rating (250 KVA and
above) used in the generating station and substation for
transforming the voltage at each end of a power transmission line.
They may be single phase or three phase, 3 wire delta/delta
delta/star connected. And of voltage rating
 220/11kv or in high voltage range. Inside the transformer a high
voltage windings are wound over low voltage winding on a metallic
core. These are three such arrangements each for a phase. The
three arrangements are inside a transformer tank, which is filled with
transformer oil. The transformer oil does the primary work of cooling
the winding and core which tends to release heat during operation.
Externally transformers have a huge appearance’s of huge metallic
containers. We can observe conservator tank, Buchhloz Relay,
Breather, Oil Temperature Indicator (OTI), Winding Temperature
Indicator (WTI) etc. It also has large radiator grills to dissipate heat
from transformer oil and cool it down.
 Breather contains silica gel which absorbs moisture also transformer
oil is given in small quantity to protect from the dust particles

51. LIGHTNING ARRESTOR
 A Lightning Arrester, Surge arrester or Line arrester is a
device used on electrical power systems and
telecommunications 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.
 Types of Lightning Arresters-
i. Rod gap arrester.
ii. Horn gap arrester.
iii. Multi gap arrester.
iv. Expulsion type arrester.
v. Valve type arrester.

52. CAPACITOR BANK
 The most common use of a capacitor bank for AC power
supply error correction is in industrial environments which
use a large number of transformers and electric motors.
Since this equipment uses an inductive load, they are
susceptible to phase shifts and power factor lags in the
power supply which can result in a loss of system
efficiency if left uncorrected. By incorporating a capacitor
bank in the system, the power lag can be corrected at the
cheapest cost.

53. DC SYSTEM
 DC distribution is needed in Sub-station to provide power
supply to Control & Protection equipment situated in
Substation in case of outages/faults.
 Generally DC power is used for this purpose instead of
AC, since the reaction time of the protective device
is less, operating on DC supply.

54. SINGLE LINE DIAGRAM

55. SPECIFICATION OF THE 33/11KV SUBSTATION
POWER TRANSFORMER
TRANSFORMER TYPE : Three Phase
KVA : 6300
VOLTS AT NO LOAD : HV-
33000
: LV-11000
AMPS : HV-110.22
: LV:330.67
FREQUENCY : 50Hz
IMPEDANCE VOLTAGE : 7.145%
VECTOR GROUP : Dyn11
COOLING TYPE : ONAN
APPROX MASS OF OIL : 2600KGS
MAX. TEMP. RISE IN OIL/ WDG. : 50 / 55 ◦C
APPROX WT. OF CORE & WDGS. :
6500KGS.

56. BIBLOGRAPHY
 GOOGLE
 VOCATIONAL TRAINING
 INDUSTRIAL VISIT