Today as a student,I am in high spiritand stepping forward into the
challenging future.Any technicalcourseis incompletewithoutsome type of
training.The course of B.Tech also requirestechnicaltraining.
I convey my thanksto PSPCL Jalandharauthorities for allowing me to do
this at their 66 KV Grid Sub Station at Jalandhar.
I would also like to expressmy gratitudeto my projectleader Er.chatur
singh(S.S.E.),who rendered invaluable helpand guidance during my
My thanks to all staff members of the division who helped directly or in
directly in completing my project.
Last but not the least I thank all the individuals who supported and criticized
me during this period of training.
PUNJAB STATE POWER CORPORATION LTD. (PSPCL)
PSPCL was incorporated as company on 16-04-2010 and was given the responsibility of operating and
maintenance of State's own generating projects. The business of Generation of power of erstwhile PSEB
was transferred to PSPCL.
4.76 lakh new connections including 61849 No. tubewell connections were released during 2007-09.
24 Hrs. Urban pattern supply made available to 12428 villages and 6158 Deras/ Dhanies with 5 or
more houses. To help SC & BPL consumers, free monthly consumption up to 200 units allowed for
connected load of 1000 watts w.e.f. 12-10-06 instead of earlier 500 watts. Strict measures have
been taken to reduce power theft. Disciplinary action taken against the erring employees and 5
numbers Anti Power Theft Police Stations have been set up. New technologies like electronic
meters, remote control of transformers, remote meter reading and HVDS system for AP/ Industries
introduced. 20.29 lakh meters out of 55.98 lakh General/ Industrial Consumers shifted out of their
premises as on 31.3.09 to curb theft of energy. All these measures have helped in reducing losses
by 4% from 23.92% (2006–07) to 19.91% (2008–09) / which resulted in substantial increase in
revenue. During 2007-09, 62 numbers New Grid substations erected and capacity at 132 number
Grid substations augmented besides addition of 1070 circuit km. Transmission line and 149 MVAR
shunt capacitors to State Grid.
Achievements Of PSPCL
Record Availability of Machines:
Being the largest hydroelectric complex in the region, PSPCL plays a vital role in the
day to day operation of the northern grid.
The PSPL powerhouses provide much needed peaking power to the grid thus
enabling the thermal stations to work on base load.
The powerhouses help in frequency regulation of the grid by flexing generation
between 1900 MW and 2800 MW in summers and between 500 MW and 1900 MW
The average annual plant availability of PSPCL powerhouses is around 88%. The
transmission line availability is around 99%.
66KV Grid Sub-Station Jalandhar
66KV grid station Jal is one of the very important power receiving and distribution centre of PSPCL is a
vital link in the northern region powr grid of country. This substation is located on sports and surgical
complex near bawakhel on the in-skirts of Jalandhar city distance of about 7 KM from Bus stand and
about 5Km from railway station of Jal. City. The entire complex is spread over an area of approx 15.
marla, out of which 5 marla have been occupied by the grid substation comprising of switch yard , control
room,pseb carrier communication centre , compressor room, battery room, 11KV switchgear room, stores
and 150/25 Ton crane bay building. The remaining area has been used for residential complex, rest
houses, club cum dispensary building, divinl and other office building, security guard huts and garages
11 KV Feeders
Sr.no TRANSFORMER (t1) TRANSFORMER (t2) TRANSFORMER (t3)
1 Gazipur Treatment plant 2 Kapurthala road
2 Variyana complex 2 Leather complex Friends
3 Sangal shoal Neel kamal Kanal
4 Basti peer daad Basti bawakhel Sutlej
5 Basti mitthu Jalandhar kunz Treatment plant 1
6 Juneja surgical Videsh sanchar
7 Variyana complex 1 Ganda nala
8 National park
9 3 spare
Equipments installed at 66 KV Grid Substation
Transformer is a static device which transform electrical energy one circuit to
another without any direct electrical connection with the help of mutual induction
between two winding
It transform power from one circuit to another circuit without changing the
frequency but may different voltage level
Working principal of Transformer
The working principal of transformer is very simple .it depends on faradays law of
Actually mutual induction between two or more winding is responsible for transformation
action in an electrical transformer
Faraday's Laws of Electromagnetic Induction
According to these Faraday's laws,
"Rate of change of flux linkage with respect to time is directly proportional to the induced EMF in a
conductor or coil".
Main Constructional Parts of Transformer
The three main parts of a transformer are,
1. Primary Winding of transformer - which produces magnetic flux when it is connected
to electrical source.
2. Magnetic Core of transformer - the magnetic flux produced by the primary winding,
that will pass through this low reluctance path linked with secondary winding and create
a closed magnetic circuit.
3. Secondary Winding of transformer - the flux, produced by primary winding, passes
through the core, will link with the secondary winding. This winding also wounds on the
same core and gives the desired output of the transformer.
A circuit breaker is an automatically
operated electrical switch designed to protect
an electrical circuit from damage caused
by overload or short circuit. Its basic function is
to detect a fault condition and interrupt current
flow. Unlike a fuse, which operates once and
then must be replaced, a circuit breaker can be
reset (either manually or automatically) to
resume normal operation. Circuit breakers are
made in varying sizes, from small devices that
protect an individual household appliance up to
large switchgear designed to protect high-
voltage circuits feeding an entire city.
All circuit breakers have common features in
their operation, although details vary
substantially depending on the voltage class,
current rating and type of the circuit breaker.The
circuit breaker must detect a fault condition; in
low-voltage circuit breakers this is usually done
within the breaker enclosure. Circuit breakers for
large currents or high voltages are usually
arranged with pilot devices to sense a fault
current and to operate the trip opening mechanism. The trip solenoid that releases the latch is usually
energized by a separate battery, although some high-voltage circuit breakers are self-contained with
current transformers, protection relays, and an internal control power source.
Once a fault is detected, contacts within the circuit breaker must open to interrupt the circuit; some
mechanically-stored energy (using something such as springs or compressed air) contained within the
breaker is used to separate the contacts, although some of the energy required may be obtained from the
fault current itself. Small circuit breakers may be manually operated, larger units have solenoids to trip the
mechanism, and electric motors to restore energy to the springs.
The circuit breaker contacts must carry the load current without excessive heating, and must also
withstand the heat of the arc produced when interrupting (opening) the circuit. Contacts are made of
copper or copper alloys, silver alloys, and other highly conductive materials. Service life of the contacts is
limited by the erosion of contact material due to arcing while interrupting the current. Miniature and
molded case circuit breakers are usually discarded when the contacts have worn, but power circuit
breakers and high-voltage circuit breakers have replaceable contacts.
When a current is interrupted, an arc is generated. This arc must be contained, cooled, and extinguished
in a controlled way, so that the gap between the contacts can again withstand the voltage in the circuit.
Different circuit breakers use vacuum, air, insulating gas, or oil as the medium the arc forms in.
Different techniques are used to extinguish the arc including:
Lengthening / deflection of the arc
Intensive cooling (in jet chambers)
Division into partial arcs
Zero point quenching (Contacts open at the zero current time crossing of the AC waveform,
effectively breaking no load current at the time of opening. The zero crossing occurs at twice the
line frequency i.e. 100 times per second for 50 Hz and 120 times per second for 60 Hz AC)
Connecting capacitors in parallel with contacts in DC circuits.
Finally, once the fault condition has been cleared, the contacts must again be closed to restore power to
the interrupted circuit..
Sulphur Hexafluoride Circuit Breaker (SF6)
High-voltage circuit breakers have greatly changed since they were first introduced in the mid-1950s, and
several interrupting principles have been developed that have contributed successively to a large
reduction of the operating energy. These breakers are available for indoor or outdoor applications, the
latter being in the form of breaker poles housed in ceramic insulators mounted on a structure.
Current interruption in a high-voltage circuit-breaker is obtained by separating two contacts in a medium,
such as sulfur hexafluoride (SF6), having excellent dielectric and arc-quenching properties. After contact
separation, current is carried through an arc and is interrupted when this arc is cooled by a gas blast of
n electrical engineering,
a disconnector or isolator switch or disconnect
switch is used to make sure that an electrical
circuit can be completely de-energised for
service or maintenance. Such switches are
often found in electrical
distribution and industrial applications where
machinery must have its source of driving
power removed for adjustment or repair. High-
voltage isolation switches are used in electrical
substations to allow isolation of apparatus such
as circuit breakers and transformers and
transmission lines, for maintenance. Often the
isolation switch is not intended for normal
control of the circuit and is used only for
solation; in such a case, it functions as a
second, usually physically distant master
switch (wired in series with the primary one)
that can independently disable the circuit even if the master switch used in everyday operation is turned
Current Transformer (C.T’s)
A current transformer (CT) is used for measurement of alternating electric currents. Current transformers,
together with voltage transformers (VT) (potential transformers (PT)), are known as instrument
transformers. When current in a circuit is too high to directly apply to measuring instruments, a current
transformer produces a reduced current accurately proportional to the current in the circuit, which can be
conveniently connected to measuring and recording instruments. A current transformer also isolates the
measuring instruments from what may be very high voltage in the monitored circuit. Current transformers
are commonly used in metering and protective relays in the electrical power industry.
Like any other transformer, a current transformer has a primary winding, a magnetic core, and a
secondary winding. The alternating current flowing in the primary produces an alternating magnetic field
in the core, which then induces an alternating current in the secondary winding circuit. An essential
objective of current transformer design is to ensure that the primary and secondary circuits are efficiently
coupled, so that the secondary current bears an accurate relationship to the primary current.
Current transformers are used extensively for measuring current and monitoring the operation of
the power grid. Along with voltage leads, revenue-grade CTs drive the electrical utility's watt-hour meter
on virtually every building with three-phase service and single-phase services greater than 200 amps.
The CT is typically described by its current ratio from primary to secondary. Often, multiple CTs are
installed as a "stack" for various uses. For example, protection devices and revenue metering may use
separate CTs to provide isolation between metering and protection circuits, and allows current
transformers and different characteristics (accuracy, overload performance) to be used for the devices.
The accuracy of a CT is directly related to a number of factors including:
Burden class/saturation class
External electromagnetic fields
The selected tap, for multi-ratio CTs
A surge arrester is a product installed near the end of any conductor of sufficient length prior to the
conductor landing on its intended electrical component. The purpose is to divert
damaging lightning induced transients safely to ground through property changes to its varistor in parallel
arrangement to the conductor inside the unit. Also called a surge protection device (SPD) or transient
voltage surge suppressor (TVSS), they are only designed to protect against electrical transients resulting
from the lightning flash, not a direct lightning termination to the conductors themselves.
Lightning termination to earth results in ground currents which pass over buried conductors and induce a
transient that propagates outward towards the ends of the conductor. The same induction happens in
overhead and above ground conductors which experience the passing energy of an atmospheric EMP
caused by the flash.
Low-voltage surge arrester Apply in Low-voltage distribution system, exchange of electrical
appliances protector, low-voltage distribution transformer windings
Distribution arrester Apply in 3KV, 6KV, 10KV AC power distribution system to protect distribution
transformers, cables and power station equipment
Protection of rotating machine using magnetic blow valve arrester Used to protect the AC
generator and motor insulation
Line Magnetic blow valve arrester Used to protect 330KV and above communication system circuit
DC or blowing valve-type arrester Use to protect the DC system’s insulation of electrical equipment
Neutral protection arrester Apply in motor or the transformer’s neutral protection
Fiber-tube arrester Apply in the power station’s wires and the weaknesses protection in the
High-frequency feeder arrester Used to protect the microwave, mobile base stations satellite
Receptacle-type surge arrester Use to Protect the terminal Electronic equipment
Network arrester Apply in servers, workstations, interfaces etc.
Coaxial cable lightning arrester Used to the coaxial cable in order to protect the wireless
transmission and receiving system
Potential transformers (PT) (also called voltage transformers (VT) are a parallel connected type of
instrument transformer. They are designed to present negligible load to the supply being measured and
have an accurate voltage ratio and phase relationship to enable accurate secondary connected metering.
The PT is typically described by its voltage ratio from primary to secondary. A 600:120 PT would provide
an output voltage of 120 volts when 600 volts are impressed across its primary winding. Standard
secondary voltage ratings are 120 volts and 70 volts, compatible with standard measuring instruments.
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
HF Transmissions: They can be used for Power Line Carrier (PLC) coupling
Transient Recovery Voltage: When installed in close proximity to HV/EHV Circuit Breakers, CVT’s
own High Capacitance enhance C/B short line fault / TRV performance
Available with standard/heavy/very heavy creepage distance
All external components are made by aluminum
Inox steel bellows
High earthquake strength capability
Suitable for ambient temperature -60 / +70 °C (extended range upon request)
Available for Line Traps mounting on the top
Best capacitance/accuracy stabilities in all service conditions
Design solutions allow to reach High Rated Capacitance in reduced CVTs dimensions
Passive ferroresonance suppression circuit provides superior damping while not degrading
Best accuracy as transient performance – suitable for ultra-rapid line protection devices
Wave Traps 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.
The Wave Traps extract the high frequency information from the power lines and route it to the
telecomm panels. They also block any surges from passing through.
Wave Traps are simply resonant circuits that produce a high impedance against PLCC carrier
frequencies (24kHz - 500kHz) while allowing power frequency (50Hz - 60Hz).
66 KV SYSTEM
Specifications of Equipments installed at 66 KV
Specification of transformers
Company name Apex Technical association ltd. Technical association
Kva 16000/20000 31500/25000 31500/25000
Volts at no load HV :66000
Ampere HV :140.0/175.0
HV ball line end 325kvp 325kvp
LV ball line and
Guranted max. temp.
rise of winding/oil
40/50 c 45 / 35 c 45 / 35
Temperature gradient c° 11.54 c° 11.54
Max. ambient temp. c° 50 c° 50 c° 50
Type of cooling ONAF/ONAN ONAF/ONAN
Impedence voltage 10% 10%
Wt. of bare copper 5200 kg 9270 kg. 9270 kg.
Core wt. 19000 kg 17900 kg 17900 kg
Wdg with insulator 9500 kg 9500 kg
Wt. of oil 8900 kg 12300 kg 12300 kg
Total mass 37400 kg 53300 kg 53300 kg
Oil litre 1000 litre 15000 litre 15000 litre
49000 kg 49000 kg
Year of manufacture 2012 2012
Max. short circuit
3 sec 5 sec. 5 sec.
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