MAHARASHTRA STATE BOARD OF TECHNICAL EDUCATION, MUMBAI

GODAVARI COLLEGE OF ENGINEERING,

(SECOND SHIFT POLYTECHNIC), JALGAON

Academic Year – 2021-2022

Semester –
First Second Third Fourth Fifth Sixth

Name of Programme – Electrical Engineering

For the course – Industrial
Training Course Code - 22049

Sr.No. Name of Enrollment

Students Number
01 Mayur Pradip Shirame 2016340012

Under the guidance of Guide – Prof. D. K. Zambare

 GODAVARI COLLEGE OF ENGINEERING,
(SECOND SHIFT POLYTECHNIC), JALGAON
Department of Electrical Engineering
Academic Year –2020-21/ 2021-22

CERTIFICATE

This is certify that

Mayur Pradip Shirame

Of 4th semester of Electrical Engineering Diploma have successfully completed the

Industrial Training. Under the guidance of as per the guidelines of Maharashtra State Board of
Technical Education, Mumbai, during the academic year – 2020-21/ 2021-22.

Project Guide Head of Electrical Engineering

Principal
 ABSTRACT

Industrial training is an important phase of a student life. A well planned, properly

executed and evaluated industrial training helps a lot in developing a professional attitude. It
develops an awareness of industrial approach to problem solving, based on a broad
understanding of process and mode of operation of organization. The aim and motivation of
this industrial training is to receive discipline, skills, teamwork and technical knowledge
through a proper training environment, which will help me a lot.
During a period of six weeks training at “Bharat Electronics”. I was assigned to
Repairing and Servicing Engineering department who plays a very important role in industry.
Throughout this industrial training, I have been learned many management skills that required
for the system, the process of the production lines and able to implement what I have learnt
for the past year as a Diploma in Electrical Engineering student in Godavari College of
Polytechnic , Jalgaon.
 Acknowledgement

I thank to the Prof. D. K. Zambare Sir, Principal of Godavari Polytechnic, Jalgaon, for
providing me the opportunity to embark on this Industrial Training. I express my sincere
gratitude to Prof. D. K. Zambare Sir, Head of Electrical Engineering Department and Mentor
Prof. C.S.Vispute Sir, Godavari Polytechnic, Jalgaon for giving me an opportunity to do my
industrial training in Bharat Electronics offered from institute Godavari Polytechnic, Jalgaon.
I sincerely thank to Bharat Electronics, for their guidance, encouragement and giving
Knowledge about industrial work in this Industrial Training .I also express my gratitude to
the official staff and other industry’s workers , Bharat Electronics, Who rendered their help in
understanding industrial work (Manufacturer Of Electrical Equipment’s) during the period of
Industrial Training .
I also thank the Maharashtra State Board Technical Education (MSBTE) for providing us
the opportunity to appear for the Industrial Training.
 TABLE OF CONTENT

1. Company profile of BEL 5

1.1. The Industry 5
1.2. Various Units 6
1.3. Corporate Motto 6
1.3.1. Corporate Objective 7
1.3.2. Quality Policy 8
1.3.2. Quality Objectives 8
2. Awards won by BEL 10
3. BEL Ghaziabad 11
4. RADAR 12
4.1. Application of RADAR 12
4.2. Working of simple RADAR 12
5. Central Services (Electrical) 14
6. Protection schemes of Power System 15
6.1. Components 15
6.2. Protective devices 15
6.3. Types of protection 16
6.4. Coordination 17
6.5. Disturbance monitoring equipment 17
6.6. Performance measures 18
7. Ring Main System 20
8. Transformer 21
8.1. Step-up Transformer 21
8.2. Step-Down Transformer 22
8.3. Protection (Buchholz Relay) 22
9. Generator 24
9.1. Diesel Generator 24
10. Circuit Breaker 25
10.1. Vacuum circuit breaker 25
10.2. AIR circuit breaker 30
11. Magnetics Department 32
12. Conclusion 35
 LIST OF FIGURES

8.1 Transformation Operation 23

8.2 Step Up transformer 24
8.3 Step Down transformer 25
9.1 Electric Generator 28
9.2 Diesel Generator 28
10.1 Circuit Breaker 29
10.2 Vacuum Circuit Breaker Operation Diagram 31
10.3 Vacuum Circuit Breaker 31
10.4 Construction of Air Blast Circuit Breaker 32
10.5 Air Circuit Breaker 32
 CHAPTER 1

COMPANY PROFILE OF BHARAT ELECTRONICS LIMITED.

1.1 THE INDUSTRY

BEL was established in 1954 as a Public-Sector Enterprise under the administrative control of
Ministry of Defense as the fountainhead to manufacture and supply electronics components
and equipment. BEL, with a noteworthy history of pioneering achievements, has met the
requirement of the state of— art professional electronic equipment for defense, broadcasting,
civil defense and telecommunication as well as the component requirement of entertainment
and chemical X- ray industry. Over the years BEL has grown to a multi-product, multi-unit
and technology driven company with track record of profit earning PSU.
BEL was born to meet the growing needs of Indian Defense Services for
electronic systems. Employing the best engineering talent available in the country. BEL as
progressed manufacturing state-of-the-art products in the field of Defense Electronics like
communications involving encryptions, Radars and strategic components.
Over the years, BEL has diversified to meet the needs of civilian customers as well
and has provided products and network solutions on turnkey basis to consumers in India and
abroad.
With the Research and Development efforts, its engineers have fructified it into a
world class organization. The company has a unique position in India of having dealt with all
the generations of electronic component and equipment. Having started with the HF receiver
and collaboration with T-CSF of France, the company’s equipment designs have had a long
voyage through the hybrid, solid-state discrete component to the state-of-art integrated circuit
technology. In the component arena also the company established its own electronic valve
manufacturing facility. It moved on to semiconductors with the manufacture of germanium
and silicon devices and then to manufacture the Integrated circuits. To keep in pace with the
component and equipment technology, its manufacturing and product assurance facilities
have also undergone a sea change. The design group has Cad’s facilities, the manufacturing
has CNC machines and a Mass Manufacture Facilities and QC checks are performed with
multi-dimensional profile measurement machines. Automatic testing machines,
environmental labs to check the weather and other
operational conditions there. All these facilities have been established to meet the stringent
requirements of MIL grade systems.
Today BEL’s infrastructure is spread over nine locations with 29 production
systems having ISO-900119002 accreditation. Product mix of the company are spread over
the entire electromagnetic (EM) spectrum ranging from tiny audio frequency semiconductor to
a huge RADAR systems and X-ray tubes on the upper edge of the spectrum. Its manufacturing
units have special focus towards the product ranges like defense communications, radars,
optical and opto- electronics, telecommunications, sound and vision broadcasting, electronic
components, etc.
Besides the manufacturing and supply of a wide variety of products, BEL
offers a variety of services like Telecom and Radar Systems Consultancy, Contact
Manufacturing, Calibration of test and measuring instruments, etc. At the moment the
company is installing MSSR radar at important airports under the modernization of airports
plan of National Airport Authority (NAA).
BEL has nurtured and build a strong in-house R&D base by absorbing
technologies from more than 50 leading companies worldwide and DRDO labs for a wide
range of products. A team of more than 800 engineers is working in R&D. Each unit has its
own R&D division to bring out new products to the production lines. Central Research
Laboratory (CRL) at Bangalore and Ghaziabad works as independent agency to undertake
contemporary design works on the state-of- art futuristic technologies. About 70% of BEL’s
products are of in-house design.
BEL was amongst the first Indian companies to manufacture computer parts and
peripherals under arrangement with International Computers India Limited (ICIL)in 1970’s.
BEL assembled a limited number of 1901 systems under the arrangement of ICIL. However,
following government’s decision to restrict the computer manufacture to ECIL, BEL could
not progress in its computer manufacturing plans.

1.2 VARIOUS UNITS

Its corporate office is at Bangalore. Bangalore complex is the BEL’s first and largest unit and
it accounts for two-thirds of both the companies turnover and manpower. This unit’s the
product range covers over 300 Defense and Civilian products.
Ghaziabad is the second largest unit of BEL and it specializes in RADARS,
COMMUNICATION EQUIPMENTS AND MICROWAVE COMPONENTS.
In total BEL has 9 units. These are distributed all over the India as:

1. BANGALORE (Corporate office)

2. GHAZIABAD
3. PANCHKULA
4. MACHILIPATNAM
5. PUNE
6. HYDERABAD
7. CHENNAI
8. KOTDWARA
9. TALOJA

The passionate pursuit of excellence at BEL is reflected in are pulsion with its customers that
can be described in its motto, mission and objectives:

1.3 CORPORATE MOTTO

“Quality, Technology and Innovation”

CORPORATE MISSION
To be the market leader in Defense Electronics and in other chosen fields and products.

1.3.1 CORPORATE OBJECTIVES

 To become a customer driven company supplying quality products at a competitive

price at expected time and providing excellent customer support.
 To achieve growth in the operations commensurate with the growth of professional
electronics industry in the country.
 To internal resources of financing the investments required for modernization,
expansion and growth for ensuring a fair return to the investor.
 In order to meet the Nation’s strategic needs, to strive for self-reliance by
indigenization of materials and components.
 To retain the technological leadership of the company in Defense and other chosen
fields of electronics through in house in research development as well as through
 collaboration/co-operation with Defense /National Research Laboratories,
International Companies, Universities and Academic institutions.
 To create an organizational culture, which encourages members of the organization to
realize their full potential through continuous learning on the job and through other
HRD initiatives?

1.3.2 QUALITY POLICY

BEL is committed to consistently deliver enhanced value to our customers, through continual
improvement of our products and processes.

1.3.3 QUALITY OBJECTIVES

1. Effective and efficient design and development process, considering the present and future
needs of customers.
2. Enhanced customers satisfaction by on time delivery of defect fee products and effective
life cycle support.
3. Continual upgradation and utilization of infrastructure and human resources.
4. Mutually beneficial alliances with suppliers.
5. Continual improvement of processes through innovation, technology and knowledge
management.

The management of BEL is convinced of the need of quality enhancement, on a continuous

basis, in the company. The need was felt to impart Education I Training to all the officers on
the basis of facts of quality management. Accordingly, an institute called Bharat Electronics
Quality Institute (BEQI) was established in 1999.
Regular training programs are conducted for all employees working in different units of the
company. Business. Excellence models being followed by different organizations are studied
and efforts are made to implement the best possible in the functioning of the organization.
Bharat Electronics Ltd. (BEL), a premier Professional Electronics Company of India, has
established and nurtured a strong-in-house R&D base over the years to emerge and remain as
a market leader in the chosen areas of business in professional electronics. Each of the nine
manufacturing units of BEL is having its own house R&D Division to develop new products
in its field of operations. Besides, there are two Central Research Laboratories (CRL) located
at Bangalore and Ghaziabad, to address futuristic technologies of interest of BEL.
Main areas of R&D activities of BEL include development of military radars, naval systems,
military communication products, electronic warfare systems, telecommunication products,
sound and vision broadcasting equipment and systems, opto-electronic products, and
electronic components. CRLperforms the dual role carrying out blue sky research for the
development of
future technologies and supporting the D&E Divisions of BEL’s nine units of state of the art
core technology solutions in areas like Embedded computers and applications, Radar Signal
Processing, VLSI designs, RE and microwave communication technologies, software
modules etc.
BEL’s R&D Units have state of art R&D infrastructure, facilities, and manpower with
relevant technical expertise for product development. There are about 1000 engineers
working in BEL on various D&E projects. BEL spends around 5% of company turnover for
the year on R&D every year. HRD divisions of BEL take adequate initiatives for the all round
development and expertise up gradation of R&D human resources. State of the art
infrastructure, test equipments, computers and work stations, software packages etc. are
augmented every year for the R&D Divisions. BEL R&D units are recognized by the
department of scientific and industrial research under the ministry of science and technology.
Government of India.
R&D Units of BEL have close interactions with other National Design Agencies like DRDO,
CSIR, C-DOT and a no. of technical institutes. BEL jointly works with them to tap suitable
indigenous designs for commercialization. Technological collaborations with some of the
Multinational companies and subsequent absorption of these technologies also have enhanced
the technological base of BEL. On an average, about 67% of BEL’S turnover is from
indigenous design, and 33% of it is through foreign technology transfers.
List of world class companies with whom BEL has technological collaborations for different
state of the art products are as given below:
 CHAPTER 2

AWARDS WON BY BEL

R&D Division of BEL have been receiving number of National R&D awards. A list of
showing various R&D awards received by BEL since 1990 is as given below:
1. FICCI award for Research in Science and Technology1990 (for the corporate
initiative of R&D).

2. DSIR National R&D award 1992.

(for successful commercialization of Public Funded
R&D). (for D&E project handled at BEL-GAD).

3. DSIR National R&D award 1993.

(for in house R&D efforts under Electronics and Electrical Industries
sector). (for D&E projects handled at BEL-Bangalore, Machilipatnam&
Ghaziabad).

4. DSIR National R&D award 1995.

(for in house R&D efforts under Electronics Industries
Sector). (for D&E projects handled at BEL-Bangalore &
Ghaziabad).

5. DSIR National R&D Award 1998.

(for successful commercialization of Public Funded
R&D). (for D&E projects handled at BEL-Bangalore and
Panchkula).

6. Defense Technology Absorption Award ’98 1999-

2000’ (sponsored by DRDO).
(for D&E projects handled at BEL-Hyderabad).

7. Award for excellence in R&D for the year 1998, 2000,

2001. (sponsored by Ministry of Information Technology,
Gol)
(for BEL Ghaziabad’s developments of various 1FF systems).
8. Award for Excellence in Professional Electronics 2000-2001, for the year
1998. (sponsored by Ministry of Information Technology, Gd).
(for BEL-KOT’s excellent performance in Production, R&D and its commitment to Quality and
Service).

9. Award for contribution in areas of Defense and R&D 2001-2002 To Col. Retd.)
H.S. Shankar, Director (R&D) for the year 2001-2002
(sponsored by Society of Defense Technologists—
SODET).
 CHAPTER 3

BEL GHAZIABAD
The second largest Unit at Ghaziabad was set up in 1974 to manufacture special types of
Radars for the Air Defense Ground Environment Systems (Plan ADGES). The Unit provides
Communication Systems to the defense forces and Microwave Communication Links to the
various departments of the State and central govt. and other users. The Unit’s products range
included Static and Mobile Radars, troposcatter equipment, professional grade Antennae and
Microwave components.
 CHAPTE 4

RADAR
RADAR is an abbreviation of word RADIO DETECTING AND RANGING. It is an
electromagnetic system for detection and location of object. It operates by transmitting a
particular type of waveform.
An elementary form of radar consists of a transmitting antenna emitting electromagnetic
radiation generated by an oscillator, receiving antenna, and an energy detecting device or
receiver. A position of the transmitted signal is intercepted by a reflecting object (target) and
is reradiated in all the directions. The receiving antenna connects the returned energy and
delivers it to the receiver, where it is processed. The distance to the target is determined by
measuring the time taken by the radar signal to travel and come back. The direction or
angular position of the target may be determined from the detection of arrival of the reflected
wavefront.
4.1 APPLICATION OF RADAR . RADAR has been employed on the ground, in air,
on the sea and in space. Some important areas of applications are:
 Air traffic control (ATC)
 Aircraft navigation
 Ship safety
 Space
 Remote Sensing
 Military

4.2. WORKING OF A SIMPLE RADAR

A simple RADAR system, as found on many merchant ships, has three main parts. They are:
1. Antenna unit or the scanner
2. the transmitter/receiver or transceiver and the visual display unit.
The antenna is about 2 or 3 meters wide and focuses the pulses of every high frequency radio
energy into a narrow vertical beam. The frequency of the radio waves is usually about 10,000
MHz. The antenna is rotated at the speed of 10 to 25 revolutions per minute so that the radar
beam sweeps through 300 degrees all around the ship out to a range of about 90 kilometers.
In all the radars it is vital that the transmitting and receiving in the transceiver are in close
harmony. Everything depends on accurate measurement of time which passes between the
transmission of the pulse and return of the ECHO about 1000 pulses per second are
transmitted. Though it is varied to suit requirement. Short pulses are best for short range
work, longer pulses are better for longer range.
An important part of the transceiver is the modulator circuit. This keys the transmitter so that
it can oscillate, or pulses, for exactly the right length of time. The pulses so generated are
video pulses. These pulses are short range pulses and hence cannot serve out long distance
communication. In order to modify these pulses into radio frequency pulses, we need to
generate power. The transmitted power is generated in device called magnetron, which can
handle these very short pulses and very high oscillations.
Between each pulse, the transmitter is switched off and isolated. The weak echoes from the
target are picked up by the antenna and fed into the receiver. To avoid overlapping of these
echoes with the next transmitted pulse, another device called duplexer is used. Thus by means
of duplexer, undisturbed, two-way communication is established. The RF echoes emerging
from the duplexer are now fed into the mixer when they are mixed with pulses of RF energy.
These pulses are generated by means of a local oscillator. Once the two are mixed, a signal is
produced in the output which is of intermediate frequency range. The 1F signals is received
by a receiver where it is demodulated to video frequency range, amplified, and then passed to
the displayed unit.
The display unit usually carried all the controls necessary for the operation of the whole
radar. It has a cathode ray tube, which consists of an electron gun in its neck. The gun shoots
a beam of electron at a phosphorescent screen at the far end. The phosphorescent screen
glows when hit by the electrons, the resulting spot of light can be seen through a glass
surface. The screen is circular and is calibrated in degrees around its edge. The electron beam
travels out from the center to the edge. This random motion of the electron beam, known as
the trace, is matched with the rotation of the antenna. So when the trace is at zero degrees on
the tube calibration, the antenna is pointing dead ahead. The beginning of each trace
corresponds exactly at the moment at which the radar energy is transmitted.
When an echo is received it brightens up the trace for a moment. This is a blip, and its
distance from the center of the tube corresponds exactly with the same time taken for the
radar pulse to travel to the target and return. So that blip of the screen gives the range and
bearing of the target. As the trace rotates, a complete picture is build up from the coating of the
tube. This type of display is called PPI (plane position indicator) and is the most common
form of presenting radar information.
 CHAPTER 5

CENTRAL SERVICES(ELECTRICAL)

The main task of this department is to supply power to all the production units, administrative
block and other parts of the factories. This department is arranged into one main station and
five substations located in the company. The power is received by the Uttar Pradesh Vidyut
Board through 33KV power line at the main station.
At the main station the power is stepped down to 11KV using 33/11KV step down
transformer. The main switch is provided with the gang operated switch, air circuit breakers
(ACB), oil circuit breaker (OCB). The air circuit breaker being used is of rating 11000V
800A. The gang operated switch is to be operated always OFF-load. This is operated when
there is some fault in the incoming power line. In case we operate the operated switch ON-
load, large amount of sparks will be produced. There are two transformers at the main station.
Out of these two only one is used at the time and second one is standby transformer i.e. it is
operated in case when first transformer does not work properly. Current transformers are used
at the main station for the measurement of the power consumption. Lightening arrestors are
used at the main station to protect the station and all the electrical equipments from being
damaged. For extra security, two different set of lightening arrestors are used one above the
other so that the station is not damaged at any cost and the excess charge gets grounded.
There are five substations at BEL which receive the power from main station at 11KV and
stepped down to 433V for the use of various machines in the factory. The transformers being
used at various sub stations are of rating 1600 KVA. These sub stations provide power to
different divisions of the factory. Like the main station these stations are also provided with
lighting arrestors. ACB’s, OCB’s, and gang operated switches.
In case of power failure these are two generators, which can provide to production divisions
only, and some other important section . These generators are imported from Czechoslovakia
and are of ascorda make. These generators are air starting type and need a pressure of 1000
pound for starting. These can develop a power of 325 bhp. And consume 400 Litres/Hr. of
diesel each. Each generator is having 6 cylinders. These have a firing order of 15-36-24 to
operate the cylinders in the same order. These are of capacity 860 KV and each generator
generates 400V at 50 Hz.This voltage is stepped up by a transformer to11KV and supplied to
the sub stations.
 CHAPTER 6

PROTECTION SCHEME OF POWER SYSTEM

Power-system protection is a branch of electrical power engineering that deals with the
protection of electrical power systems from faults through the isolation of faulted parts from
the rest of the electrical network. The objective of a protection scheme is to keep the power
system stable by isolating only the components that are under fault, whilst leaving as much of
the network as possible still in operation. Thus, protection schemes must apply with very
pragmatic and pessimistic approach to clearing system faults. The devices that are used to
protect the power systems from faults are called protection devices.

6.1 COMPONENTS

Protection systems usually comprise five components:

 Current and voltage transformers to step down the high voltages and currents of the
electrical power system to convenient levels for the relays to deal with.
 Protective relays to sense the fault and initiate a trip, or disconnection, order;
 Circuit breakers to open/close the system based on relay and auto recloser commands;
 Batteries to provide power in case of power disconnection in the system.
Communication channels to allow analysis of current and voltage at remote terminals of a line
and to allow remote tripping of equipment.
For parts of a distribution system, fuses are capable of both sensing and disconnecting faults.
Failures may occur in each part, such as insulation failure, fallen or broken transmission lines,
incorrect operation of circuit breakers, short circuits and open circuits. Protection devices are
installed with the aims of protection of assets, and ensure continued supply of energy.
Switchgear is a combination of electrical disconnect switches, fuses or circuit breakers used
to control, protect and isolate electrical equipment. Switches are safe to open under normal
load current, while protective devices are safe to open under fault current.

6.2. PROTECTIVE DEVICE

 Protective relays control the tripping of the circuit breakers surrounding the
faulted part of the network
  Automatic operation, such as auto-re-closing or system restart
 Monitoring equipment which collects data on the system for post event
analysis While the operating quality of these devices, and especially of protective
relays, is always critical, different strategies are considered for protecting the different
parts of the system. Very important equipment may have completely redundant and
independent protective systems, while a minor branch distribution line may have very
simple low-cost protection.

There are three parts of protective devices:

 Instrument transformer: current or potential (CT or VT)
 Relay
 Circuit breaker

Advantages of protected devices with these three basic components include safety,
economy, and accuracy.
 Safety: Instrument transformers create electrical isolation from the power
system, and thus establishing a safer environment for personnel working with
the relays.
 Economy: Relays are able to be simpler, smaller, and cheaper given lower-
level relay inputs.
 Accuracy: Power system voltages and currents are accurately reproduced by
instrument transformers over large operating ranges.

6.3. TYPES OF PROTECTION

 Generator sets – In a power plant, the protective relays are intended to prevent
damage to alternators or to the transformers in case of abnormal conditions of
operation, due to internal failures, as well as insulating failures or regulation
malfunctions. Such failures are unusual, so the protective relays have to operate very
rarely. If a protective relay fails to detect a fault, the resulting damage to the
alternator or to the transformer might require costly equipment repairs or
replacement, as well as income loss from the inability to produce and sell energy.
 High-voltage transmission network – Protection on the transmission and
distribution serves two functions: Protection of plant and protection of the public
(including
 employees). At a basic level, protection looks to disconnect equipment which
experience an overload or a short to earth. Some items in substations such as
transformers might require additional protection based on temperature or gas
pressure, among others.
 Overload and back-up for distance (overcurrent) – Overload protection requires a
current transformer which simply measures the current in a circuit. There are two
types of overload protection: instantaneous overcurrent and time overcurrent (TOC).
Instantaneous overcurrent requires that the current exceeds a predetermined level for
the circuit breaker to operate. TOC protection operates based on a current v/s time
curve. Based on this curve if the measured current exceeds a given level for the preset
amount of time, the circuit breaker or fuse will operate.
 Earth fault ("ground fault" in the United States) – Earth fault protection again
requires current transformers and senses an imbalance in a three-phase circuit.
Normally the three phase currents are in balance, i.e. roughly equal in magnitude. If
one or two phases become connected to earth via a low impedance path, their
magnitudes will increase dramatically, as will current imbalance. If this imbalance
exceeds a pre- determined value, a circuit breaker should operate. Restricted earth
fault protection is a type of earth fault protection which looks for earth fault between
two sets current transformers (hence restricted to that zone).
 Distance (impedance relay) – Distance protection detects both voltage and current.
A fault on a circuit will generally create a sag in the voltage level. If the ratio of
voltage to current measured at the relay terminals, which equates to an impedance,
lands within a predetermined level the circuit breaker will operate. This is useful for
reasonable length lines, lines longer than 10 miles, because its operating
characteristics are based on the line characteristics. This means that when a fault
appears on the line the impedance setting in the relay is compared to the apparent
impedance of the line from the relay terminals to the fault. If the relay setting is
determined to be below the apparent impedance it is determined that the fault is
within the zone of protection. When the transmission line length is too short, less
than 10 miles, distance protection becomes more difficult to coordinate. In these
instances the best choice of protection is current differential protection.
  Back-up – The objective of protection is to remove only the affected portion of plant
and nothing else. A circuit breaker or protection relay may fail to operate. In
important systems, a failure of primary protection will usually result in the operation
of back-up protection. Remote back-up protection will generally remove both the
affected and unaffected items of plant to clear the fault. Local back-up protection will
remove the affected items of the plant to clear the fault.
 Low-voltage networks – The low-voltage network generally relies upon fuses or
low- voltage circuit breakers to remove both overload and earth faults.

6.4 COORDINATION

Protective device coordination is the process of determining the "best fit" timing of current
interruption when abnormal electrical conditions occur. The goal is to minimize an outage to
the greatest extent possible. Historically, protective device coordination was done on
translucent log– log paper. Modern methods normally include detailed computer based
analysis and reporting.Protection coordination is also handled through dividing the power
system into protective zones. If a fault were to occur in a given zone, necessary actions will
be executed to isolate that zone from the entire system. Zone definitions account for
generators, buses, transformers, transmission and distribution lines, and motors. Additionally,
zones possess the following features: zones overlap, overlap regions denote circuit breakers,
and all circuit breakers in a given zone with a fault will open in order to isolate the fault.
Overlapped regions are created by two sets of instrument transformers and relays for each
circuit breaker. They are designed for redundancy to eliminate unprotected areas; however,
overlapped regions are devised to remain as small as possible such that when a fault occurs in
an overlap region and the two zones which encompass the fault are isolated, the sector of the
power system which is lost from service is still small despite two zones being isolated.

6.5. DISTURBANCE MONITORING EQUIPMENT

Disturbance-monitoring equipment (DME) monitors and records system data pertaining to a

fault. DME accomplish three main purposes:
 model validation,
 disturbance investigation, and
 assessment of system protection performance.
DME devices include:
 Sequence of event recorders, which record equipment response to the event.
 Fault recorders, which record actual waveform data of the system primary voltages
and currents.
  Dynamic disturbance recorders (DDRs), which record incidents that portray power
system behavior during dynamic events such as low frequency (0.1 Hz – 3 Hz)
oscillations and abnormal frequency or voltage excursions.

6.6. PERFORMANCE MEASURES

Protection engineers define dependability as the tendency of the protection system to operate
correctly for in-zone faults. They define security as the tendency not to operate for out-of-zone
faults. Both dependability and security are reliability issues. Fault tree analysis is one tool with
which a protection engineer can compare the relative reliability of proposed protection
schemes. Quantifying protection reliability is important for making the best decisions on
improving a protection system, managing dependability versus security tradeoffs, and getting
the best results for the least money. A quantitative understanding is essential in the
competitive utility industry. Performance and design criteria for system-protection devices
include reliability, selectivity, speed, cost, and simplicity.

Reliability: Devices must function consistently when fault conditions occur, regardless of
possibly being idle for months or years. Without this reliability, systems may result in high
costly damages. Selectivity: Devices must avoid unwarranted, false trips.
Speed: Devices must function quickly to reduce equipment damage and fault duration, with
only very precise intentional time delays.
Economy: Devices must provide maximum protection at minimum cost.
Simplicity: Devices must minimize protection circuitry and equipment.
 CHAPTER 7

RING MAIN SYSTEM

In electricity supply, a ring final circuit or ring circuit (often incorrectly called a ring main or
informally a ring) is an electrical wiring technique developed and primarily used in the
United Kingdom. This design enables the use of smaller-diameter wire than would be used in
a radial circuit of equivalent total current. Flexible cords connected between appliance and
plugs intended for use with sockets on a ring circuit are individually protected by a fuse in the
plug.
Ideally, the ring circuit acts like two radial circuits proceeding in opposite directions around
the ring, the dividing point between them dependent on the distribution of load in the ring. If
the load is evenly split across the two directions, the current in each direction is half of the
total, allowing the use of wire with half the current-carrying capacity. In practice, the load
does not always split evenly, so thicker wire is used.
 CHAPTER 8

TRANSFORMERS

A transformer is an electrical device that transfers electrical energy between two or more
circuits through electromagnetic induction. Electromagnetic induction produces an
electromotive force within a conductor which is exposed to time varying magnetic fields.
Transformers are used to increase or decrease the alternating voltages in electric power
applications. A varying current in the transformer's primary winding creates a varying
magnetic flux in the transformer core and a varying field impinging on the transformer's
secondary winding. This varying magnetic field at the secondary winding induces a varying
electromotive force (EMF) or voltage in the secondary winding due to electromagnetic
induction. Making use of Faraday's Law (discovered in 1831) in conjunction with high
magnetic permeability core properties, transformers can be designed to efficiently change AC
voltages from one voltage level to another within power networks.

Fig. 8.1. Transformer Operation

8.1 STEP-UP TRANSFORMER

A step-up transformer is the direct opposite of a step-down transformer. There are many turns
on the secondary winding than in the primary winding in the step-up transformers. Thus, the
voltage supplied in the secondary transformer is greater than the one supplied across the
primary winding. Because of the principle of conservation of energy, the transformer converts
low voltage, high- current to high voltage-low current. In other words, the voltage has been
stepped up. We can find step-up transformers located near power plants that are designed to
operate megawatts of power. Apart from the power plants, step-up transformers can also be
used for local and smaller
applications such as x-ray machine which requires about 50,000 volts to work. Even a micro-
wave oven requires a small step-up transformer to operate. The type of metal winding used is
one of the considerations used in determining the efficiency of transformers. Copper coils are
more efficient than many other coil metal choices such as aluminum. However, copper
windings tend to cost more, but you can expect to save the initial cost over time as the
efficiency of the material will save on electrical cost.

Fig. 8.2. Step-up Transformer

8.2. STEP-DOWN TRANSFORMER

There are two types of transformers, namely: Step down and Step up transformers. Generally,
the difference between them is the amount of voltage produced, depending on the number of
secondary coils. In a step-down transformer is one who secondary windings are fewer than
the primary windings. In other words, the transformer’s secondary voltage is less than the
primary voltage. So, the transformer is designed to convert high-voltage, low-current power
into a low-voltage, high current power and it is mainly used in domestic consumption. A
common case of step-down application is in the case of door bells. Normally, door bells use
16 volts, but most household power circuits carry 110-120 volts. Therefore, the doorbell’s
step-down transformer receives the
110 volts and reduces it to lower voltage before supplying it to the doorbell. Step-down
transformers are mostly used to convert the 220 volts electricity to the 110 volts required in
most domestic equipment.

Fig. 8.3. Step-Down Trandformer

8.3. PROTECTION (BUCHHOLZ RELAY)

In the field of electric power distribution and transmission, a 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.
APPLICATION: Buchholz relays have been applied to large power transformers at least
since the 1940s, and are connected between the conservator and oil tank of a transformer.
OPERATION: 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
electrical 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.
Buchholz relays have a test port to allow the accumulated gas to be withdrawn for
testing. Flammable gas found in the relay indicates some internal fault such as
overheating or arcing, whereas air found in the relay may only indicate low oil level or a
leak.
 CHAPTER 9

GENERATOR

A generator is a device that converts mechanical energy to electrical energy for use in an
external circuit. The source of mechanical energy may vary widely from a hand crank to an
internal combustion engine. Generators provide nearly all the power for electric power grids.
The reverse conversion of electrical energy into mechanical energy is done by an electric
motor, and motors and generators have many similarities. Many motors can be mechanically
driven to generate electricity and frequently make acceptable generators.

Fig. 9.1. Electric Generator

9.1 DIESEL GENERATOR

A diesel generator is the combination of a diesel engine with an electric generator (often an
alternator) to generate electrical energy. This is a specific case of engine-generator. A diesel
compression-ignition engine often is designed to run on fuel oil, but some types are adapted
for other liquid fuels or natural gas. Diesel generating sets are used in places without
connection to a power grid, or as emergency power-supply if the grid fails, as well as for
more complex applications such as peak-lopping, grid support and export to the power grid.
Sizing of diesel generators is critical to avoid low-load or a shortage of power and is
complicated by modern electronics, specifically non-linear loads. In size ranges around 50
MW and above, an open cycle gas turbine is more efficient at full load than an array of diesel
engines, and far more compact, with comparable capital costs; but for regular part-loading,
even at these power levels, diesel arrays are sometimes preferred to open cycle gas turbines,
due to their superior efficiencies.

Fig. 9.2 Diesel Generator

 CHAPTER 10

CIRCUIT BREAKER

A circuit breaker is an automatically operated electrical switch designed to protect an

electrical circuit from damage caused by overcurrent or overload or short circuit. Its basic
function is to interrupt current flow after protective relays detect a fault. 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. The generic function of a circuit
breaker, RCD or a fuse, as an automatic means of removing power from a faulty system is
often abbreviated to ADS (Automatic Disconnection of Supply).

Fig. 10.1. Circuit Breaker

10.1 VACUUM CIRCUIT BREAKERS

The Vacuum Circuit Breakers (VCB) are particularly advantageous for use in the voltage
range 3 kV to 38 kV. In the Vacuum Circuit Breaker the arc interruption takes place in
vacuum in the interrupter. The pressure inside the vacuum interrupter is maintained below
10-4 torr. At this low pressure very few molecules are available inside the interrupter
chamber. This is one desired characteristic of the interrupting medium for more efficient arc
quenching.
OPERATION: For opening the circuit breaker, the operating mechanism separates the
moving contact from the fixed contact inside the interrupter. Just at the point of contact
separation, a very small amount of metal vaporizes from contact tip and arc is drawn between
the contacts. Current flows between the contacts through this arc. Due to the sinusoidal nature
of the AC current, the current after reaching the maximum value decreases so reducing the
vapour emission. Near zero value of the sinusoidal current wave the arc is extinguished. The
metal vapour is deposited on the condensing shield (see Fig-A). The space inside the
interrupter being high vacuum, very little ions are available between the electrodes/contacts. So
after arc extinction the space between the contacts regains dielectric strength very rapidly
which is the most desired characteristics of the arc quenching medium. Due to the rapid
regaining of dielectric strength of vacuum inside the interrupter the re-striking does not takes
place. In the figure below is shown the main constructional features of a Vacuum Circuit
Breaker (VCB). The vacuum condensing shield is used so that the metallic vapour does not
condenses on the enclosure glass. In the absence of the shield the metallic vapour condenses on
the glass and gradually the glass becomes conducting, so that the insulation between the
moving and fixed contacts is lost in the open condition of the breaker. The metallic bellow
makes it possible to maintain vacuum inside the interrupter chamber while allowing the
movement of moving contact for separation from the fixed contact. One side of the bellows is
welded to the moving contact stem as shown while the other side is welded to the interrupter
end plate. The contact surface is so designed that the arc between the contacts diffuse. The arc
spread to the sides of the contact surfaces. Diffusion of arc reduces its strength hence the arc
quenching is facilitated. The main requirements of the contact material is, very high electrical
and thermal conductivity, low contact resistance and high melting point.

ADVANTAGES:

 The vacuum interrupters have long life.

 Unlike oil CB (OCB) or air blast CB (ABCB), the explosion of VCB is avoided. This
enhances the safety of the operating personnel.
 No fire hazard.
 The vacuum CB is fast in operation so ideal for fault clearing. VCB is suitable for
repeated operation.
 Vacuum circuit breakers are almost maintenance free.

 Due to the rapid gain of dielectric strength of vacuum interrupter, the separation
required between the moving contact from fixed contact is of the order of few
millimetre. This makes the VCB compact.
  VCB is light weight.
 No exhaust of gas to the atmosphere.
 Quiet operation.

DISADVANTAGES:

 The main disadvantage of VCB is that it is uneconomical for use of VCB at voltages
exceeding 38 kV. The cost of the breaker becomes prohibitive at higher voltages. This
is due to the fact that at high voltages (above 38 kV) more than two numbers of
interrupters are required to be connected in series.
 Advance technology is used for production of vacuum interrupters.

(a) (b)
Fig. 10.2. Vacuum Circuit Breaker operational diagram (a), Vacuum Circuit Breaker (b)

10.2 AIR CIRCUIT BREAKER

Air Circuit Breaker is a device used to provide Overcurrent and Short Circuit Protection for
circuits ranging from 800 Amps to 10000 Amps. One should not be confused between Air
Circuit Breaker and Air Blast Circuit Breaker. Air Circuit Breakers are usually used in low
voltage applications below 450 volts. We can today find these in Distribution Panels (below
450 volts). Air Blast Circuit Breakers are high capacity breakers and can be seen in old
substations mainly above 132 kV. The working principle of these two circuit breakers are
quite different. Here we will only discuss the working of Air Circuit Breaker (ACB).
OPERATION: Air Circuit breakers normally have two pairs of contacts. The main pair of
contacts carries the current at normal load and these contacts are made of copper. The
additional pair is the arcing contact and is made of carbon. When circuit breaker is being
opened, the main contacts open first and during opening of main contacts the arcing contacts
are still in touch with each other. As the current gets. a parallel low resistive path through the
arcing contact during opening of main contacts. there will not be any arcing in the main
contact. The arcing is only initiated when finally the arcing contacts are separated. The each
of the arc contacts is fitted with an arc runner which helps. the arc discharge to move upward
due to both thermal and electromagnetic effects as shown in the figure. As the arc is driven
upward it enters in the arc chute, consisting of splatters. The arc in chute will become colder,
lengthen and split hence arc voltage becomes much larger than system voltage at the time of
operation of air circuit breaker, and therefore the arc is quenched finally during the current
zero. Air Circuit breakers (ACBs) are available which can be Electrically Operated or
Manually Operated. This means electrically operated Air Circuit Breaker Can be Opened
(switched OFF) and Closed (Switched ON) using external power supply. The Electrically
operated motor is used to operate spring charging mechanism for closing and opening the
Circuit Breaker. The power supply could be single phase 230V AC Supply or low voltage
24V-110V DC supply for operation during no availability of power. Air Circuit breakers
(ACBs) are also available as Fixed Type and Withdrawable (Drawout) Type formats.

Fig. 10.4 Air Circuit Breaker

Fig. 10.3 construction of air blast circuit
 CHAPTER 11

MAGNETICS DEPARTMENT

This department is making all types of transformers and coils that are used in various
equipment’s. This department basically consists of four sections:

1. Planning section
2. Mechanical assembly section
3. Moldings sections
4. Inspection

The D&E department gives the following description- numbers of layers, numbers of
turns/layers, types of winding, gapes in core, insulation between layers, ac/dc impedance,
dielectric strength, electrical parameters and earthing.
The various types of transformers being made are:

1. Open type transformer

2. oil cooling types transformers
3. molding type of transformer
4. PCB molding type transformers

Transformers are mechanically assembled, leads are taken out and checking of specification
is done.

Winding machines of are of three types:

1. Heavier one- DNR for 0.1 to 0.4 mm diameter.
2. LC control machines.
3. Torroidal machines having 32 operations from winding to mechanical assembly.

The various types of windings used are:-

1. Hand-winding
2. Torroidal winding
3. Sector winding
4. Pitch winding
5. Variable winding
6. Wave winding
Two types of cores used are:

1. E-type for 3-phase

2. C-type for single phase.

Various procedures involved in the manufacture of transformers are:

1. Formers of glass- expoxy.

2. Winding.
3. Core Winding.
4. Varnishing.
5. Impregnation various varnished coils are heated, then cooled, reheated and put into
vacuum. Then air is blown to remove the humidity.
6. Molding-araldite mixed with black dye is used to increase mechanical as well as
electrical strength. Molding is done at 120 degrees centigrade for twelve hours.
7. A RDB compound is used for leakage production, oil is boiled at 70 to 80 degrees
under vacuum conditions to remove air bubbles after this the cols are dipped in
vamish and core is attached.
8. Painting
9. Mechanical assembly
10. Termination
11. Testing: dielectric testing is done at 50KV voltage applied for a minimum of one minute.
During inspection, the following characteristics are checked:-
(a) turn ratio
(b) DC resistance for each coil.
(c) Inductance
(d) No load voltage
(e) leakage
 CONCLUSION

The practical training aims at familiarizing the students with the working condition in a
professional firm as well as to apply their theoretical knowledge acquired in the institute into
practice.
This training was helpful to me in various direct and indirect ways, like understanding of
machines as well as procedure followed on a manufacturing a product. A good insight into
inspection and quality check of products.
This training has added a whole new dimension to my observation and practical approach as
well as introducing me to Organizational Hierarchy.