The document provides an overview of the 33/11kV Phidim substation located in Phidim, Panchthar district, Nepal. It was established in 2058 BS by Nepal Electricity Authority. The substation steps down electricity from the national 33kV grid to 11kV to supply power to local areas. It is responsible for controlling energy exchange, load shedding, fault analysis and improving the transmission system. The substation layout, single line diagram, and organizational structure are presented. Key equipment used includes transformers, circuit breakers, isolators, lightning arrestors, and insulators.

1. CHAPTER-1
OVER VIEW OF ORGANIZATION
1.1 Introduction
Phidim substation was established on 2058 BS. Which is located in phidim municipality,
panchthar district is the result of Nepal Electricity Authority. It is responsible for the protection
of the transmission system, controlling the Exchange of energy, load shedding, fault analysis and
pin-pointing the cause and subsequent improvement in the area of field.
1.1.1 About33/11kV Phidimsubstation
The main bus 33KV is connected to national grid. Now the transmission line first parallel
connected with lightning arrester to diverge surge, followed by CT connected parallel. CT
measures voltage and steeps down at 110V A.C for control panel. A current transformer is
connected in series with line which measure current and step down current at ratio 800:1 for
control panel.
Switchgear equipment is provided, which is the combination of a circuit breaker having an
isolator at each end. After that the line is connected to Bus bar. From Bus bar 33kV line is
supplied to taplejung district. Lightning arrester is also connected in Bus bar. From busbar 33kv
line is stepped down to 11kv with power transformer connected through isolator. The power
transformer is of 3MVA. 11KV line is supplied to phidim bazar, jorpokhari. A step down
transformer of 11KV/440V is connected to control panel to provide supply to the equipment of
the substation. Battery bank of 110v is provided for dc supply to operate relay
1.1.2 Missionofphidimsubstation
1. Ensure steady State & Transient stability.
2. Controlling the exchange of energy.
3. Load shedding and prevention of loss of synchronism. Maintaining the system frequency
within targeted limits.
4. Voltage Control and protection of transmission line.
5. Securing the supply by proving adequate line capacity.
6. Fault analysis and pin-pointing the cause and subsequent improvement in that area of field.
7. Determining the energy transfer through transmission lines.
8. Reliable supply by feeding the network at various points.
9. Establishment of economic load distribution and several associated functions

2. 1.1.3 Layout diagram of substation.
Figure shows the civil structure layout of substation.
Figure 1: Layout diagram of substation

3. 1.1.4 Locationofsubstation
Phidim substation is located in phidim municipality of panchthar district in eastern Nepal.
Figure 2: Top view of substation

4. 1.1.5 Singlelinediagram
Figure3:SingleLineDiagram

5. 1.1.6 OrganizationStructure
DIRECTOR
SUB-DIRECTOR
SUPERVISOR
TECHNICIAN
Figure 4: Organization Structure

6. 1.2 Switch yard Component use in substation:
Following are the substation equipment:-
 Transformer
 Power Transformer
 Distribution Transformer
 Current Transformer
 Potential Transformer
 Circuit Breaker
 Isolator
 Capacitor Bank
 Lightning Arrester
 Conductors
 Switchgear
 Insulator
 Earthing
 Bus-bars etc.
1.2.1 Transformer:
Transformer is a static machine, which transforms the potential of alternating current at same
frequency. It means the transformer transforms the low voltage into high voltage & high voltage
to low voltage at same frequency. It works on the principle of static induction principle.
When the energy is transformed into a higher voltage, the transformer is called step up
transformer but in case of other is known as step down transformer.
Following are the types of transformers:
 Power Transformer
 Distribution Transformer
 Current Transformer
 Potential Transformer

7. 1) PowerTransformer
The power transformer generally used in the generating station and substation. The
size of the power transformer is above than 250 KVA. They are delta/delta or
star/delta connected transformers. They are operated from normal load to peak load
and are disconnected during light load period. Therefore they have generally ratio of
iron loss to copper loss is 1:1. This is the reason that the power transformer is
designed to have maximum efficiency at load. They are designed to have large
reactance since current controlling is much more importance than that of voltage
regulation. This is the most important component of the substations. The main work
of a substation is to distribute power at a low voltage, by stepping down the voltage
that it receives in its incoming lines. Power is generally transmitted over long
distances at very high voltages, generally in the range of 400 KV, 200 KV, 132 KV,
66KV, 33KV to the substations. However a consumer requires power at rather low
voltages, 11 KV for industries and 440V or 230V for domestic consumers. The
substations use step-down transformers to attain this voltage and then distribute this
power.
In phidim substation transformers rating of 3MVA is used for 33/11KV for supply
power in transmission and distribution lines.
Figure 5: Power Transformer

8. 2) DistributionTransformer:
A distribution transformer is a transformer that provides the final
voltage transmission in the electrical power distribution system, stepping down voltage to
the level used by customers. These transformers are located near the consumer’s localities and
step down to 400V, 3-phase, 4-wire for supplying to the consumers. The voltage between any two
phases is 400V & between any phase and neutral it is 230V. Distribution transformers may be
oil filled or dry-filled. Distribution Transformers consist of two primary components:
Core and Coil. Coil is a conductor, or winding, typically made of a low resistance
material such as aluminum or copper. Copper or aluminum conductors are wound around
a magnetic core to transform current from one voltage to another. Liquid insulation
material or air (dry-type) surrounds the transformer core and conductors to cool and
electrically insulated the transformer. A core made of magnetically permeable material
like grain oriented steel.
Distribution transformers are either mounted on an overhead pole or on a concrete pad at
ground level. There is some evidence to suggest that pole mounted transformers
dissipates heat more easily than pad mounted units and may therefore be more fully
loaded.
Figure 6: Pole mounted Distribution Transformer

9. 3) CurrentTransformer:
Current transformer is an
instrument transformer, used along with measuring
or protective devices, in A which the secondary
current is proportional to the primary current.
Current transformers supply the protective relays
with currents of magnitude proportional to those of
power circuit but sufficiently reduced in magnitude.
The measuring devices cannot be directly connected
to the high magnitude supplies. Hence current
transformers are used to supply those devices with
currents of magnitude proportional to those of power.
A current transformer also isolates the measuring
instruments from high voltage circuits. The ratio of
CT is 75/5 A used in phidim substation.
4) Potential Transformer:
Voltage transformers (VT)
(also called potential transformers (PT)) are a parallel
connected type of instrument transformer, used for
metering and protection in high-voltage circuits or
pharos phase shift isolation. They are designed to
present negligible load to the supply being measured
and to have an accurate voltage ratio to enable
accurate metering. A potential transformer may have
several secondary windings on the same core as a
primary winding, for use in different metering or
protection circuits. The ratio of PT use in substation
was 33000/110 V incoming feeder and 11000/110 V
for outgoing feeder.
Figure 7: Potential Transformer
Figure 7: Current Transformer
Figure 8: Potential Transformer

10. 1.2.2 CircuitBreaker
Electrical circuit breaker is a switching device which can be operated manually and
automatically for controlling and protection of electrical power system respectively. As
the modern power system deals with huge currents, the special attention should be given
during designing of circuit breaker for safe interruption of arc produced during
the operation of circuit breaker.
Vacuum circuit breakers are circuit breakers which are used to protect medium and high
voltage circuits from dangerous electrical situations. Like other types of circuit breakers,
vacuum circuit breakers literally break the circuit so that energy cannot continue flowing
through it, thereby preventing fires, power surges, and other problems which may emerge.
These devices have been utilized since the 1920s, and several companies have introduced
refinements to make them even safer and more effective.
Figure 8: Vacuum Circuit BreakerFigure 9: Vacuum Circuit Breaker

11. 1.2.3 Isolator
A mechanical switching device which is used to make or break the circuit under no load
condition is known as isolator. it is also called disconnecting switch and used extensively
for disconnection feeder, circuit breaker, bus-bar etc. for their regular repair and
maintenance work because this device is designed to operate under no load condition. It is
very simple in construction and is a cheapest device used in power system controlled. An
isolator is used in bus-bar system for generating station, power substation and distribution
substation for switching of bus-bar for repair and maintenance work. Because its simple
constructional feature and being cheapest among the switchgear. They are also used to
require the circuit breaker for economy.
Centre break isolator are use in phidim substation.
Types of isolator are as follows:
 Central break
 Vertical swing
 Central rotating
 Pento graph
Figure 10: Center Rotating Isolator

12. 1.2.4 LightingArrestor
A lightning arrestor is a device used in
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. 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.
1.2.5 Insulator
An electrical insulator is a material whose internal electric charges do not flow freely, and
therefore make it very hard to conduct an electric current under the influence of an electric
field. The insulator serves two purposes. They support the conductors (bus bar) and confine
the current to the conductors. The most common used material for the manufacture of
insulator is porcelain. There are several types of insulators
 Shackle Insulator
In early days, the shackle insulators were used as strain insulators. But
now a day, they are frequently used for low voltage distribution lines.
Such insulators can be used either in a horizontal position or in a
vertical
 Pin type Insulator
As the name suggests, the pin type insulator is mounted on a pin on
the cross-arm on the pole. There is a groove on the upper end of
the insulator. The conductor passes through this groove and is tied
to the insulator with annealed wire of the same material as the
conductor. Pin type insulators are used for transmission and
distribution of electric power at voltages up to 33 kV. Beyond
operating voltage of 33 kV, the pin type insulators become too
bulky and hence uneconomical.
Figure 11: Shackle Insulator
Figure 12: Pin Type Insulator
Figure 11: Lighting Arrestor
Figure 12: Shackle Insulator
Figure 13: Pin Type Insulator

13.  Suspension Insulator
For voltages greater than 33 kV, it is a usual practice to use
suspension type insulators shown in Figure. Consist of a
number of porcelain discs connected in series by metal links
in the form of a string. The conductor is suspended at the
bottom end of this string while the other end of the string is
secured to the cross-arm of the tower. The number of disc
units used depends on the voltage.
 Strain Insulator
A dead end or anchor pole or tower is used where a
straight section of line ends, or angles off in another
direction. These poles must withstand the lateral
(horizontal) tension of the long straight section of wire.
In order to support this lateral load, strain insulators are
used.
For low voltage lines (less than 11 kV), shackle insulators are used as strain insulators.
However, for high voltage transmission lines, strings of cap-and-pin (disc) insulators are
used, attached to the cross arm in a horizontal direction. When the tension load in lines is
exceedingly high, such as at long river spans, two or more strings are used in parallel
position. They can be directly fixed to the pole with a bolt or to the cross arm.
Figure 14: Suspension Insulator
Figure 15: Strain Insulator

14. 1.2.6 Bus-bar
When numbers of generators or feeders operating at the same voltage have to be directly
connected electrically, bus bar is used as the common electrical component. Bus bars are made
up of copper rods operate at constant voltage. The following are the important bus bars
arrangements used at substations:
 Single bus bar system
 Single bus bar system with sectionalized.
 Duplicate bus bar system
In large stations it is important that break downs and maintenance should interfere as little
as possible with continuity of supply to achieve this, duplicate bus bar system is used. Such a
system consists of two bus bars, a main bus bar and a spare bus bar with the help of bus coupler,
which consist of the circuit breaker and isolator. In substations, it is often desired to disconnect a
part of the system for general maintenance and repairs. An isolating switch or isolator
accomplishes this. Isolator operates under no load condition. It does not have any specified
current breaking capacity or current making capacity. In some cases isolators are used to
breaking charging currents or transmission lines.
While opening a circuit, the circuit breaker is opened first then isolator while closing a circuit the
isolator is closed first, then circuit breakers. Isolators are necessary on supply side of circuit
breakers, in order to ensure isolation of the circuit breaker from live parts for the purpose of
maintenance. In phidim substation single busbar system type of bus bar are used.
Figure 15: Bus-barFigure 16: Bus-Bar

15. 1.2.7 Earthing
In an electrical installation or an electricity supply system an earthing system or grounding
system connects specific parts of that installation with the Earth's conductive surface for
safety and functional purposes. The point of reference is the Earth's conductive surface, or on
ships, the surface of the sea. The choice of earthing system can affect the safety and
electromagnetic compatibility of the installation. Regulations for earthing systems vary
considerably among countries and among different parts of electrical systems, though many
follow the recommendations of the International Electro technical Commission which are
described below. This article only concerns grounding for electrical power.
Examples of other earthing systems are listed below with links to articles:
 To protect a structure from lightning strike, directing the lightning through the earthing
system and into the ground rod rather than passing through the structure.
 As part of a single-wire earth return power and signal lines, such as were used for low
wattage power delivery and for telegraph lines.
 In radio, as a ground plane for large monopole antenna.
A functional earthing connection serves a purpose other than electrical safety, and may carry
current as part of normal operation. The most important example of a functional earth is the
neutral in an electrical supply system when it is a current-carrying conductor connected to the
earth electrode at the source of electrical power. Other examples of devices that use
functional earth connections include surge suppressors and electromagnet interference filters.
Figure 16: EarthingFigure 17: Earthing

16. 1.3 Relay and Panel Section Component
1.3.1 Relay
In a power system it is inevitable that immediately or later some failure does occur somewhere in
the system. When a failure occurs on any part of the system, it must be quickly detected and
disconnected from the system. Rapid disconnection of faulted apparatus limits the amount of
damage to it and prevents the effects of fault from spreading into the system. For high voltage
circuits relays are employed to serve the desired function of automatic protective gear. The
relays detect the fault and supply the information to the circuit breaker.
The electrical quantities which may change under fault condition are voltage, frequency, current,
phase angle. When a short circuit occurs at any point on the transmission line the current flowing
in the line increases to the enormous value. This result in a heavy current flow through the relay
coil, causing the relay to operate by closing its contacts. This in turn closes the trip circuit of the
breaker making the circuit breaker open and isolating the faulty section from the rest of the
system. In this way, the relay ensures the safety of the circuit equipment from the damage and
normal working of the healthy portion of the system. Relay works on two main operating
principles, Electromagnetic attraction and Electromagnetic Induction
RELAY USED IN CONTROLLING PANEL OF SUBSTATION
.Differential Relay
A differential relay is one that operates when vector difference of the two
or more electrical quantities exceeds a predetermined value. If this
differential quantity is equal or greater than the pickup value, the relay
will operate and open the circuit breaker to isolate the faulty section.
. Over Current Relay
This type of relay works when current in the circuit exceeds the
predetermined value. The actuating source is the current in the circuit
supplied to the relay from a current transformer. These relay are used on
A.C. circuit only and can operate for fault flow in the either direction.
This relay operates when phase to phase fault occurs.
Figure 17: Differential Relay
Figure 18: Over Current Relay
Figure 18: Differential Relay
Figure 19: Over Current Relay

17. . Earth Fault Relay
This type of relay sense the fault between the lines and the earth. It
checks the vector sum of all the line currents. If it is not equal to
zero, it trips.
. Tripping Relay
This type of relay is in the conjunction with main relay. When
main relay sense any fault in the system, it immediately
operates the trip relay to disconnect the faulty section from the
section.
. Auxiliary Relay
An auxiliary relay is used to indicate the fault by glowing bulb or
showing various flags.
Figure 19: Earth Fault Relay
Figure 20: Tripping Relay
Figure 21: Auxiliary Relay
Figure 20: Earth Fault Relay
Figure 21: Tripping Relay
Figure 22: Auxiliary Relay

18. 1.3.2 Control panel
Figure 23: Control Panel
Metal-clad cubicles designed with withdraw able trucks and divided into several compartments
are usually employed. The several compartments in which the cubicle is divided are control
compartment, indicating and metering instrument and protective device compartment, circuit
breaker and operating mechanism compartment, main bus-bar compartment and current
transformers and cable sealing box compartment. The circuit breaker and its operating
mechanism are mounted on the truck, which can be withdrawn from the cubicle. In withdraw
able-truck unit-type cubicles the isolating device is of the plug-in type. When the truck is rolled
out from the cubicle the holes n which the isolating device enters for making contact are
automatically close by metal shutters serving to isolate the live part from possible casual contact.
When the truck is rolled back into the cubicle, the shutters open automatically.
To prevent any possible opening or closing of the disconnecting devices when the circuit breaker
is closed, these cubicles are designed with interlocks which prevent the truck from being rolled
in or withdraw when the circuit breaker is closed.

19. 1.4 Battery Bank
Figure 24: Battery Bank
It is used to supply the backup power to the specified feeder and the indicating lamps of the
panel board. Its rating is 110V. The most critical component of a protection, control and
monitoring (PCM) system is the auxiliary dc control power system. The heart of a substation is
the battery bank. If this were to fail, an electric utility could expose all feeders associated with
the station to a condition where they could not ever trip in a fault. Any backup devices, such as
the main breaker on the low-voltage side or the high-voltage side protection of the power
transformer, would all be inoperative.

20. 1.5 Conductors use in Substation Design
An ideal conductor should fulfill the following requirements:
a) Should be capable of carrying the specified load currents and short time currents.
b) Should be able to withstand forces on it due to its situation. These forces comprise self-
weight, and weight of other conductors and equipment, short circuit forces and
atmospheric forces such as wind and ice loading.
c) Should be corona free at rated voltage.
d) Should have the minimum number of joints.
e) Should need the minimum number of supporting insulators.
f) Should be economical.
The most suitable material for the conductor system is copper or aluminums. Steel may be
used but has limitations of poor conductivity and high susceptibility to corrosion.
In an effort to make the conductor ideal, three different types have been utilized, and these
include: Flat surfaced Conductors, Stranded Conductors, and Tubular Conductors

21. 1.6 Sub-stationProtection
1.6.1 Transformer Protection
Transformers are totally enclosed static devices and generally oil immersed.
Therefore chances of fault occurring on them are very easy rare, however the
consequences of even a rare fault may be very serious unless the transformer is
quickly disconnected from the system. This provides adequate automatic protection
for transformers against possible faults. Various protection methods used for
transformers are:-
 Buchholz Relay
Buchholz relay is a safety device mounted on some oil-filled
power transformers and reactors, equipped with an external
overhead oil reservoir called a conservator. The Buchholz
Relay is used as a protective device sensitive to the effects
of dielectric failure inside the equipment.Depending on the
model, the relay has multiple methods to detect a failing
transformer. On a slow accumulation of gas, due perhaps to
slight overload, gas produced by decomposition of insulating
oil accumulates in the top of the relay and forces the oil level
down. A float switch in the relay is used to initiate an alarm
signal.
Depending on design, a second float may also serve to detect
slow oil leaks.If an arc forms, gas accumulation is rapid, and
oil flows rapidly into the conservator. This flow of oil operates
a switch attached to a vane located in the path of the moving
oil. This switch normally will operate a circuit breaker to
isolate the apparatus before the fault causes additional damage.
 Conservator and Breather
When the oil expands or contacts by the change in the temperature,
the oil level goes either up or down in main tank. A conservator is
used to maintain the oil level up to predetermined value in the
transformer main tank by placing it above the level of the top of the
tank. Breather is connected to conservator tank for the purpose of
extracting moisture as it spoils the insulating properties of the oil.
During the contraction and expansion of oil air is drawn in or out
through breather silica gel crystals impregnated with cobalt chloride.
Silica gel is checked regularly and dried and replaced when
necessary.
Figure 24: Buchholz Relay
Figure 25: Breather
Figure 25: Buchholz Relay
Figure 26: Silica Gel Breather

22.  Marshalling box
It has two meter which indicate the temperature of the oil and
winding of main tank. If temperature of oil or winding
exceeds than specified value, relay operates to sound an
alarm. If there is further increase in temperature then relay
completes the trip circuit to open the circuit breaker
controlling the transformer.
 Transformer cooling
When the transformer is in operation heat is generated due to iron losses the removal of heat is
called cooling.
There are several types of cooling methods, they are as follows:
1. Air natural cooling
In a dry type of self-cooled transformers, the natural circulation of surrounding air is
used for its cooling. This type of cooling is satisfactory for low voltage small
transformers.
2. Air blast cooling
It is similar to that of dry type self-cooled transformers with to addition that continuous
blast of filtered cool air is forced through the core and winding for better cooling. A fan
produces the blast.
3. Oil natural cooling
Medium and large rating transformers have their winding and core immersed in oil,
which act both as a cooling medium and an insulating medium. The heat produce in the
cores and winding is passed to the oil becomes lighter and rises to the top and place is
taken by cool oil from the bottom of the cooling tank.
4. Oil blast cooling
In this type of cooling, forced air is directed over cooling elements of transformers
immersed in oil.
Figure 26: Marshalling BoxFigure 27: Marshalling Box

23. 5. Forced oil and forced air flow (OFB) cooling
Oil is circulated from the top of the transformers tank to a cooling tank to a cooling
plant. Oil is then returned to the bottom of the tank.
6. Forced oil and water (OWF) cooling
In this type of cooling oil flow with water cooling of the oil in external water heat
exchanger takes place. The water is circulated in cooling tubes in the heat exchanger.
1.6.2 BusbarProtection
Faults in a power system can be either apparatus faults or bus faults. Apparatus fault refer to
faults in feeders, transformers, generators or motors. On the other hand bus is an external
interconnection point for terminals of different apparatus. A bus fault is usually rare, but if
and when it happens its consequences can be quite severe. It can lead loss of multiple
feeders or transmission lines and hence has a potential to create a large enough disturbance
to induce transient instability. Even if it does not lead to transient instability, loss of load
from an important substation can be quite high. Because of these reasons, bus
rearrangement can have sufficient redundancy so that in case of a bus fault, an alternative
bus automatically takes over the functions of the ‘main bus'. Thus, the end user sees no
disruption in service except during the fault interval. This can however involve significant
costs, via the cost of new busbar and additional circuit breakers to configure a parallel
arrangement. Hence, different bus configurations are used in practice – each one
representing a different tradeoff between cost, flexibility and redundancy.
Also there are various methods of bus protection given as following:
• Overcurrent
• Trip Blocking Schemes
• Communication‐Based Schemes
• High‐Impedance Current Differential
• Low‐Impedance Current Differential
• Distance
• Linear Coupler
• Arc Flash Detection

24. 1.6.3 FeedersProtection
Faults occurring on overhead and underground distribution feeders caused by various
sources including:
• Faulty equipment
• Environmental induced faults: wind, lightning, ice, snow-storm, sag due to extreme
temperature, salt spray
• Falling tree limbs
• Animal contacts
• People induced including: pole and overhead contacts and underground digging
Faults occurring in the distribution system must be sensed quickly and immediately isolated
to prevent hazards to the general public and utility personnel. Protective relays are used to
sense short circuit conditions caused by faults in distribution protection schemes and the use
of proper schemes and settings can help to maximize sensitivity and selectivity.
Some permanent faults can be equipment failures or cables cut or short-circuited by
excavation equipment. The type of grounding of the distribution system affects the voltage
and current characteristics during a fault. Proper protection strategies should be employed to
make dependability an utmost criterion.
Basic feeder protection principles are well-known. Phase and ground overcurrent functions
reliably detect most faults. Reclosing is often applied to restore service following temporary
faults on overhead circuits. Security is maintained through time and pickup coordination
between overcurrent devices that may operate for a specific fault event. The challenge in
feeder protection is reliable operation during unusual fault events such as high impedance
ground faults and adjacent feeder faults. A key advantage of microprocessor based feeder
relays is the ability to protect against these unusual faults, while improving the operation of
the distribution system through flexibility, programmability and communications.

25. CHAPTER-2
INTERNSHIPDETAILS
2.1 Replacement of Silica Gel
Silica gel crystal has tremendous capacity of absorbing moisture. When air passes through these
crystals in the breather; the moisture of the air is absorbed by them. Therefore, the air reaches to
the conservator is quite dry, the dust particles in the air get trapped by the oil in the oil seal cup.
The oil in the oil sealing cup acts as barrier between silica gel crystal and air when there is no
flow of air through silica gel breather. The color of silica gel crystal is dark blue but, when it
absorbs moisture; it becomes pink. When there is sufficient difference between the air inside the
conservator and the outside air, the oil level in two components of the oil seal changes until the
lower oil level just reaches the rim of the inverted cup, the air then moves from high pressure
compartment to the low pressure compartment of the oil seal. Both of these happen when the oil
acts as core filter and removes the dust from the outside air.
When gel absorbs moisture its colour slowly changes into dark blue to light blue to pink. Pink
colour indicates the gel is saturated and should be replaced.
Figure 27: Silica Gel Breather
Figure 28: Silica Gel Breather

26. 2.2 Replacement of Tripping coil of Outgoing Feeder
Tripping coil is a control device that utilizes a solenoid to open circuit breaker. Trip coil is used
to serve the purpose of tripping the breaker while current exceeds the certain limit (Due to
overload or fault) .
Tripping coil was burnt out that is why while checking the trip health in control panel board its
light didn’t glow. So replacement of tripping coil was done.
Perhaps occasionally a coil on a solenoid valve may burn out because of a defect in its
manufacture. But usually the cause can be traced to some abnormal condition either in operating
conditions of the machine on which the valve is installed, or to unusual environmental conditions
Figure 28: Tripping coilFigure 29: Tripping Coil

27. CHAPTER-3
CONCLUSION ANDRECOMMENDATION
3.1 Suggestion for Improvement:
 There is no any capacitor bank so we suggest for connection of capacitor bank for PF
improvement.
 Some measuring instrument on control panel was not reading the value properly, so these
should be replaced or repair.
 Testing of equipment whether they are operating well or not should be checked time to
time.
 Replacement of the analog measuring instrument with digital instrument.
 Regular cutting of tall bushes and climbing grass which may touch the live conductor.
 Means of communication is telephone so we recommended for optical fiber
communication to communicate between substations.
3.2 Conclusion
Now from this report we can conclude that electricity plays an important role in our life. We are made
aware of how the transmission of electricity is done. We too came to know about the various parts of the
Substation system. The major stations include a control room from which operations are coordinated.
Smaller distribution substations follow the same principle of receiving power at higher voltage
on one side and sending out a number of distribution feeders at lower voltage on the other, but
they serve a more limited local area and are generally unstaffed. The central component of the
substation is the transformer, as it provides the effective in enface between the high- and low-
voltage parts of the system. Other crucial components are circuit breakers and switches.
Breakers serve as protective devices that open automatically in the event of a fault, that is, when
a protective relay indicates excessive current due to some abnormal condition. Switches are
control devices that can be opened or closed deliberately to establish or break a connection

28. 3.3 Reference
1. www.slideshare.com
2. www.wikipedia.com
3.