1. 1
Department of Electrical Engineering
College of Engineering, Pune
INTERNSHIP IN SIEMENS, NASHIK
Report Submitted by
Name : Amol Nanaji Bagul
Enrolment Number : 20903007
MIS Number : 110905002
Dates of Submission : 06-07-2011

2. 2
ACKNOWLEDGEMENT
With all respect and gratitude, I would like to thank all people who
have helped me directly or indirectly for this internship.
I express my heartily gratitude towards Mr.Pitale, Mrs.Jadhav,
Mr.Koshe, Mr.Bhatia, Mr.Shinde, Mr.Lohar, Mr.Sundar, Mr.Chaudhari
and entire staff of Siemens, nashik.
I am ending this acknowledgement with deep indebtedness of my
friends who have helped me complete manuscript.
Amol Nanaji Bagul
Enrollment No:EE-20903007

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INDEX
Topic Page No.
1. SIENEMS HISTORY………………………………………………………………..5
2. PRODUCTS DEPARTMENT……………………………………………..…………6
2.1 INTRODUCTION………………………………………………………………..6
2.2 AUXILIARY CONVERTERS…………………………………………………...6
2.2.1 NATURAL COOLCOACH CONVERTER……………………................6
2.2.2 AUXILIARY AC ELECTRICAL LOCO………………………………..7
2.3 TRACTION CONVERTER……………………………………………...............7
2.3.1 ELECTRIC MULTIPLE UNIT……………………………………………7
2.3.2 DEISEL ELECTRIC TRACTION CONVERTER……………………….12
2.3.2.1 ELECTRICAL CONTROL CABINET 1………………….............,13
2.3.2.2 ELECTRICAL CONTROL CABINET 2…………………..............16
2.3.2.3 ELECTRICAL CONTROL CABINET 3…………………..............16
3. ELECTRONIX AND SIGNALLING……………….................................................17
3.1 INTRODUCTION……………………………………………………….............17
3.2 ELECTRONIX…………………………………………………………………...17
3.2.1 DIGITAL AXEL COUNTER (DAC)………………………………………18
3.2.2 AUDIO FREQUENCY TRACK CONTROL……………………………...18
3.2.3 AUTOMATIC WARNING SYSTEM……………………………………...19
3.3 TESTING………………………………………………………………………....19
3.3.1 CARD LEVEL TESTING…………………………………………..............20
3.3.2 SYSTEM LEVEL TESTING……………………………………….............20
3.4 SIGNALLING…………………………………………………………………...20
3.4.1 TYPES OF K-50 RELAY…………………………………………..............21
3.4.2 DETAIE PROCESS ABOUT K-50 MANUFACTURING………...............21
4. MEDIUM VOLTAGE DRIVE……………………………………………...............24

4. 4
4.1 INTRODUCTION……………………………………………………………….24
4.2 NEED OF MV DRIVE…………………………………………………………..24
4.3 FEATURES OF MV DRIVE……………………………………………………24
4.4 CELL(SECONDARY DELTA CONNECTION)……………………………….24
4.5 APPLICATIONS OF MV DRIVE………………………………………………25
5. PROGARMABLE LOGIC CONTROLLER……………………………………….26
5.1 BASICS OF PLC………………………………………………………...............26
5.2 PARTS OF PLC………………………………………………………………….26
5.3 TESTING OF PLC……………………………………………………………….29
5.4 ADDITIONAL ADVANTAGES OF PLC………………………………………29
6. RESEARCH AND DEVELOPMENT DEPARTMENT…………………................30
6.1 INTRODUCTION………………………………………………….....................30
6.2 PRODUCT DEVELOPMENT CYCLE………………………………………....30
6.3 R&D PRODUCT………………………………………………………...............31

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1. Siemens-History
1957
- The Company was incorported on 2nd March, as a private limited company
under the name Siemens Engineering and Manufacturing Company of India
Private Limited.
- The Company Manufacture switchboards, switch gear, different types of
motors upto 315 KW, assembly of railway signaling equipment, X-ray and
other electromedical equipment, installation, testing and commissioning of
electrical plant and equipment undertaking repair work of motors, generators,
transformers, calorific and measuring instruments, certain household appliances
and marine electrical equipment and selling of products manufactured by the
Company as well as those of its licensees.
- On 23rd March, the Company entered into a collaboration agreement with two
foreign companies, viz., Siemens & Halske AG and Siemens-Schuckertwerke
AG of West Germany.
1967
- The name of the Company was changed from Siemens Engineering &
Manufacturing Co. of India Ltd., to Siemens India Ltd., with effect from 23rd
October. The name of the company again changed from
Siemens India Ltd.,to Siemens Ltd., with effect from 31st March, 1987.

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2. Products Department
2.1 Introduction:
Mumbai railway is the main customer of Siemens Nasik. So the products
department is devoted for all the railway engine requirements. All types of
converters are manufactured here in Nasik plant. All the products can be
classified as below:
2.2 Auxiliary converters:
These converters are mainly used to convert the DC input from
battery to AC. This AC is used for numerous operations such as fans, lights,
battery charger, break components etc. This is the reason why they are called as
AUXILIARY converters. They are described as below.
2.2.1 Natural Cool Coach Converters:
As the name suggests, this converter is used in Air-conditioned
cabinets. Initially these converters are mounted above the buggies. But now-a-
days they are placed near the wheels i.e. below the boogies. It consists of 2 step-
up choppers and 1 inverter unit.
Products
Auxiliary
converters
Natural Cool
Coach
Converter
Auxiliary AC
Electric Loco
Traction
converters
EMU
Diesel Electric
Traction
Converter

7. 7
Input of 110V DC comes from the battery. This is stepped up to
650V DC with the help of choppers. Outputof choppers is the input for inverter.
Inverter converts 650V DC to 415V three phase AC.
This 415V AC is then used for the air-conditioners in the boogies.
The whole set-up is naturally cooled.
2.2.2 Auxiliary AC Electric Loco:
As the name suggests, it is the Auxiliary controller for the electric
motor. Input of 760V single phase AC comes from the battery which is passed
through rectifier units to convert it to DC. The DC is then passed through two
parallel inverters. Output of inverters is 415V three phase AC.
Loco Integrates
1. Control of many functions such as light ON/OFF, fan ON/OFF
2. An Operating & display unit from which driver can control all the
functions
3. Power supply i.e. battery for the input.
4. Interface for expansion modules.
5. An Interface for program modules and PC cable.
6. Easy to use basic functions that are often required in day to day
operations. E.g. functions for ON/OFF relays.
7. Loco offers solutions for domestic installations & engineering. e.g.
stairway lighting, external lighting, sun blinds, shutters.
2.3 Traction converters:
2.3.1 Electrical Multiple Unit:
The traction converter cabinet for "EMU Bombay" uses IGBT
technology with air cooled power semiconductors. The traction converter is
delivered as a completely assembled unit. Because the traction converter is
designed for installation within the HT Compartment, there are no operation-
or indication elements on this unit. The traction control unit (TCU) SIBAS
32S is situated inside of the cabinet, the operation- and indication elements

8. 8
have to be at the disposal of the driver and for this reason are situated in the
driver’s cab.
 Functional sections ofthe tractionconverter in AC Mode:
The traction converter consists of the following functional sections in the AC
Mode
operation.
• Input and pre-charging
• Four-quadrant chopper
• DC link circuit
• Pulse width modulated inverter & Braking chopper
1. Input and pre-charging
When the converter is put into operation, first the DC link
capacitor of the inverter is pre-charged before the main contactor is
closed using diodes in 4QC modules. This prevents the high inrush
current, which would result if the input voltage was suddenly switched
onto the empty converter. The main contactor is switched on after the DC
link voltage has reached 90 % of the theoretical final charge
Fig Input section in AC mode of operation
2. Four quadrant chopper (4QC):

9. 9
A four-quadrant chopper consists of a bridge as shown below in
Fig. 3-4. The purpose of the 4QC is to transform the input voltage
(generally single phase AC from the transformer) into a controlled direct
voltage for the DC link circuit. The term 4QC signifies that the phase
angle between voltage and current is freely adjustable while driving as
well as while braking. Through the combination of phase situation and
mode of operation all four operational quadrants can be obtained.
Fig circuit diagram of 4 quadrant chooper
3. DC link circuit:
Fig. DC link circuit

10. 10
The DC link capacitor is required as an energy storage unit. It
provides the reactive power and serves to smooth the DC link voltage. In
DC mode, the DC link capacitor is part of the LC line filter. It provides
over voltage protection and helps improve system perturbation (through
reducing the harmonic component in the DC link current). Capacitor C1
to C4 each of 3mF is put in parallel as shown in Fig.3-7. Hence the total
bank has a capacity of 12mF.
4. Pulse Width Modulated Inverter and Brake Chopper
The PWM inverter comprises three phase modules. At the output
terminals U, V,W, the inverter provides a three-phase voltage system
where frequency and voltage can be adjusted.
Fig. Circuit diagram of the PWM inverter
The IGBTs can be essentially defined as basic switches with a high
clock frequency. The input to the PWMI is the DC link voltage. The
switching sequences of IGBTs are selected so that a sinusoidal current is
obtained. The voltages between two output terminals are now observed.
The maximum possible amplitude of the phase-to-phase output voltage is
a function of the magnitude of the DC link voltage.

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 Functional sections of the traction converter in DC Mode
The traction converter consists of the following functional sections
in the DC Mode operation:
• Input and pre-charging
• DC link circuit
• Pulse width modulated inverter and Brake Chopper
1. Input and pre-charging
When the converter is put into operation, first the DC link
capacitor of the inverter is pre-charged before the main contactor is
closed. This is achieved by switching on K5.1 and K5.2. When K5.1 and
K5.2 are switched on the DC Link capacitors (C1-C4) gets pre-charged
through precharging resistor R32. This prevents the high inrush current.
The main contactor K6.1 and K6.2 is switched on after the DC link
voltage has reached 90 % of the final voltage
Fig Input circuit, DC Mode

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2.DC link circuit
Refer to the AC Mode of operation.
3. Pulse Width Modulated Inverter and Brake Chopper
Refer to the AC Mode of operation
2.3.2 Diesel Engine Traction Converter:
This converter is equipped with a turbocharged 16 cylinder diesel engine
to drive the main generator. The main generator converts diesel engine
mechanical power into alternating current (AC) electrical power. The internal
rectifier banks of the main generator convert alternating current to direct current
(DC) thereby providing a DC power output. The DC output from the main
generator is called the DC link voltage and is applied to the traction inverters.
DC link voltage varies with the throttle position from 600 VDC at TH1 to 2600
VDC at TH8. The inverters change DC power into variable AC power. There is
one traction inverter for each parallel set of three traction motors. Traction
inverter TCC1 and traction inverter TCC2 invert the DC link voltage into
variable voltage, variable frequency, 3 phase AC power for the induction
traction motors. Each of the inverters is controlled by a separate computer. Both
inverter computers are in turn controlled by a primary computer known as the
EM2000 Locomotive Control Computer (LCC) that monitors and controls many
locomotive functions. One EM2000 display panel, mounted in the door of the
main electrical locker, is driven by the EM2000 computer and indicate
operating conditions, system faults, and troubleshooting information.
 LOCOMOTIVE OPERATION
When the engine start switch is held in PRIME, the locomotive
computer starts the fuel pump which pressurizes the injection system with
fuel. The fuel pump moves the fuel from the fuel tank under the
locomotive to the injectors. After the entire system has been supplied
with fuel, the engine can be started by holding the PRIME/START

13. 13
switch in START. With the engine running, the fuel pump motor is
powered directly by the auxiliary generator.
The main generator rotates at engine speed, generating alternating
current (AC) power. This power is then converted to direct current (DC)
power by rectifier banks within the generator assembly and applied to the
DC link. A switch gear applies the DC link voltage to traction inverter
circuits. The traction inverters convert the DC link voltage to 3-phase AC
power for the traction motors.
2.3.2.1 Electrical Control Cabinet 1(ECC1):
The electrical control cabinet, Figure 8-34, houses some of the electrical
and electronic equipment needed to power and control the locomotive. This
equipment includes principally –
 The No. 1 Circuit Breaker Panel –

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The No. 1 circuit breaker panel, Figure 8-35, contains circuit breakers and
switches used in the control and protection of diesel engine and electrical
systems. The circuit breakers can be operated as switches but will trip open
when an overload occurs. The circuit breaker portion of the panel is divided into
sections. Breakers in the shaded section must be ON (lever up) during
locomotive operation. Breakers in the unshaded section are to be used as
conditions require.
Some of them are :
1. LIGHTS C.B.
2. HDLTS (headlights)
3. RADIO
4. EVENT RECORDER
5. CAB FANS
6. AIR DRYER
 ENGINE CONTROLPANEL:
Various switches and controls used in the operation of the locomotive are
mounted on the engine control panel. Figure 8-36 shows the Engine
Control Panel.
Figure Engine control panel
It consists of:

15. 15
1. ISOLATION Switch
2. EXTERIOR LIGHTS Switch (Rear Platform & Fuel Station)
3. MAINTENANCE (Engine room) LIGHTS Switch
4. EFCO (Emergency Fuel Cut off) / STOP Switch
5. BATTERY CHARGING Ammeter
 NO. 2 CIRCUIT BREAKER AND TEST PANEL
The No. 2 circuit breaker compartment, Figure 8-37, has provisions for
circuit breakers as well as a test panel intended for use by maintenance
personnel during maintenance and testing procedures. All three circuit
breakers must be ON (lever up) during locomotive operation.
 MAIN CONTROL PANEL
Many smaller electrical devices such as relays and resistors are
mounted on the main control panel, Figure 8-38, which is located inside
the Electrical Control Cabinet across the top back wall. These devices are
listed, starting at the top right corner looking into the front (cab side) of
the cabinet
1. RE HDLT DIM A & DIM B
2. RE HDLT HE A - HE B
3. BWR - BRAKE WARNING RELAY

16. 16
4. EFCO - EMERGENCY FUEL CUTOFF AND ENGINE
STOP RELAY
5. AR - ALARM RELAY
6. FPR - FUEL PUMP RELAY
2.3.2.2 Electrical Control Cabinet 2(ECC2):
This cabinet is mainly used for starting of the locomotive. For starting the
locomotive, solenoid motors have to be stared. There are two types of
contactors used for this purpose. When auxiliary contactoris turned ON, the
path for main contactors get completed and ultimately motors get started and
hence locomotive gets started.
2.3.2.3 Electrical Control Cabinet 3(ECC3):
Heat is generated in large amount in any locomotive due to running of
motors. To cool down the heated components, ECC3 is used. It, actually ,
reduces the speed according to the temperature in the locomotive which
alternatively serves the purpose of cooling down the components.

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3. ELECTRONICS AND SIGNALLING
3.1 INTRODUCTION:
The safety of rail operations is based on the safety of many
individual components. This is ensured by the use of signalling and safety
systems and devices that interoperate smoothly.
This is the section where the railway signalling products are
manufactured according to the customer requirements. The main customer is
Mumbai railway. The system indicates the track vacancy so that railway driver
can decide his path. Also some of the systems control the speed , track existence
etc.
Track vacancy detection systems provide reliable information
about the clear occupied states of track sections and thus make a decisive
contribution towards virtually trouble-free operation.
The department has two sub-departments namely Electronics and
Signalling. Decision of Electronic system is given to the Signalling section
which is an electromagnetic part of the system containing relays.
3.2 ELECTRONICS:
This is the department where systems indicating vacancy of
railway track are manufactured. The different cards such as transmitter card,
receiver card, driver card etc are manufactured in Germany and are tested and
assembled here in Nashik.
Total three systems are assembled in Nashik plant. These three
systems use different concept to indicate vacancy of the railway track. They are
explained as follows.
3.2.1 Digital Axel Counter (DAC):
Here in this system the whole railway track is divided into
sections. As the name suggests DAC measures the number of axels incoming to

18. 18
sections and outgoing from the same axel. If both the numbers are same then it
gives the decision that ‘the track is vacant’.
There are two different technical systems in use:
 Track circuits :
Track circuit transmits electric energy from a transmitter to a
receiver via the two insulated rails of a track section. While current
is flowing , a track section is indicating as being vacant. If the track
section is occupied or used by a train, the circuit is short circuited
via the vehicle axels and the current does not reach the receiver.
 Axle counting systems :
Axle counting systems contain counting heads at beginning and
end of each track section to be detected. These units are connected
to an evaluation computer which processes the information
generated by the counting heads. If the number of axles counted in
matches that counted out, the respective track section is indicated
as being vacant.
Salient features of the system are:
 High effectiveness
 Compactness
 Easy extendibility
 Continuous and reliable output of the clear and occupied states of points
3.2.2 Audio Frequency track Control (AFTC) :
Audio-frequency track circuits are used for the precision clear or
occupied indication of track sections. The track section is remote-fed with a
frequency-modulated voltage. Transmitter and receiver can be accommodated
centrally in the interlocking up to 6.5 km from the track section.

19. 19
AFTC is used on main-line railways as well as on metro, rapid transit, and
suburban railways. Apart from track vacancy detection, there are other potential
applications for the FTG S track circuit, for example:
 Triggering a train number indication
 Activating train destination indicators on platforms
Some of the salient features of AFTC are:
 Joint-less vacancy detection.
 Rail breakage detection possible.
 Vacancy detection of partial track section possible.
3.2.3 Automatic Warning System (AWS):
This is the advanced system of track vacancy in which train is
automatically stopped when certain conditions are not satisfied. Suppose some
speed limit is fixed and it is exceeded due to some reasons then the system
raises the emergency alarm three times. Even though if speed is not lowered
then train is automatically stopped.
There can be rail track damage in the way of train. In this case this
system stops the train immediately. This system is used in Mumbai local in
large scale.
In this way AWS helps rail transaction to be safe.
3.3 Testing:
Testing of the system is very important aspect before dispatching
the order. Especially in track vacancy systems, it is very essential to test the
system for desired results because a fault in functioning of the system may
result in loss of many lives.
Testing of track vacancy systems is divided in two main stages as
follows.

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3.3.1 Card level testing:
Different cards for any of the track vacancy systems are
manufactured in Germany and are tested in Nasik. Every card is followed by a
test procedure suggested by research and development department. Card level
testing includes following tests:
 In-circuit test:
PCB used for different cards are multi-layer PCB. This is the test where
component mountability. Also values of resisters, capacitor, inductors
etc are verified. Polarity of different components such as diode is
checked. Open tracks, short tracks are verified according to the design.
 Isolation test:
This is the test in which isolation voltage and isolation resistance is
measured as given in test procedure. Isolation resistance and voltage are
measured group by group. When one group is under test, other groups
are shorted. Expected values of isolation resistance and voltage are
given in the test procedure manual suggested by research and
development department.
3.3.2 System level testing:
Once every card is tested ok from all card level test then all cards
are assembled as per the design n the whole system is tested for its
functionality.
Now the system is ready for dispatch.
3.4 SIGNALLING:
Signalling part mainly consists of relays.
One such relay namely K-50 relay is described here.
K-50 relay:
 Relay is an Electromagnetic device.

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 It is named as K-50 because in German “contact” is written as “kontakt”
and 50 is the year when relay was introduced.
3.4.1 Types of K-50 relay
1) Neutral relay :
-There are 3 subtypes i.e. A,B,E.
-A is simple relay while B and E are special purpose relay.
-These relays are also classified according to their combination of NO and NC.
2) Interlock relay :
-It is made up of two neutral relays.
-They are mechanically interlocked by means of latching.
-They are named as upper relay and lower relay. When upper relay is NO, lower
relay is NC and vice-versa.
3) AC immunized relay :
-This is a special purpose relay used where , there is superimposition of AC
current over DC current line.
-can be identified by square block assembled with coil.
-It is a B type relay.
3.4.2 Detail Process About k-50 manufacturing:
It is divided into 3 main categories as follows:

22. 22
1. Assembly of relay :
 Spring contact riveting:
In this operation a silver rivet is riveted at the end and an angle is
provided to spring at the other end for maintaining contact pressure
between contacts.
 Picketing:
In this procedure plates are insulated by an insulating material like
Bakelite.
 Packet bending:
In this operation contacts are bend at different angle with respect to
lower.
 Packet tinning:
In this process end contacts are dipped into a solder paste and kept for
some time. Due to tinning it improves solder ability of contacts.
2. Adjustments of relays :
 Stroke is the distance between anchor and packet while wipe is distance
between two plates. These two things are adjusted as per requirement and
then practically they are tested.
 Principle of relay :
Detail Process About k-50 manufacturing
Relay
Assymbly
Relay
Adjustment
Relay
Testing

23. 23
CYC (core yoke coil) is a magnetic part of relay. When connected to electric
supply, it magnetises the core and anchor got attracted. And when supply is
removed core releases the anchor. Thus NO and NC operations are done.
 Matching:
It is very important step in adjustment of relay.
The angle of the anchor is checked (10 deg) and then anchor is put on the CYC.
 Function:
The face of the brass rivet should match with the face of the core.
This is adjusted here.
3. Relay testing:
 Mechanical Inspection:
The total stroke should be as given in the manual. It is checked in mechanical
inspection.
In the same way contact pressure should in the recommended range. Relay
functioning largely depends on contact pressure.
 Electrical Inspection:
All the electrical connections should be accurate for proper functioning of
relay.
All the connections are checked for short circuit, connectivity etc.

24. 24
4. Medium Voltage Drive
4.1 Introduction:
Medium Voltage Drive, often called as MV Drive, is also called as three phase
dry type transformer. This is because in this drive principle of transformer is
used.
4.2 Need of MV drive:
 If the user uses low voltage input then for the specified power application
he will need more current input
 As power input increases, heat losses increases and so efficiency of the
system decreases.
 Also power factor of system decreases and user may have to pay the
penalty offered by utility.
 So it is necessary to increase the voltage input so that less current is
required.
 Also, the voltage input should vary according to the frequency of motor.
 So it is required to have a regulated medium voltage drive output.
4.3 Features of MV drive:
 KVA rating of this drive is 700 KVA.
 Primary connections is star while Secondary are delta.
 Winding used is copper winding.
 It can sustain temperature rise upto 115 degree celcius.
 There is only one primary winding while there are 18 secondary
windings.
 Primary input is 6.6Kv and secondary output is also 6.6Kv and 350 Kw
power.
 Out of 18 secondary connections output of one tapping is 630 V and
current is 35 A.
4.4 Cell (Secondary delta connection) :

25. 25
 Construction of MV drive is complicated as it has only one primary and
18 secondary.
 Primary is star connected and given three phase 6.6Kv input.
 In secondary side 18 tappings are divided in three group and each group
having 6 tappings in series.
 As above stated output of each tapping is 630 V.
 From each group one tapping is selected and we get three phase 630 V
which is given as input to the Cell.
 Cell is a device in which one bridge rectifier and one capacitor bank is
used.
 Bridge rectifier is rectifier having 6 diodes to rectify A.C. voltage to pure
D.C.
 Capacitor bank is to remove ripples in the waveform during rectification.
 Thus we get single phase A.C. from one cell.
 Such 6 cells from all the tapping gives total output as 6.6Kv but
controlled.
4.5 Applications of MV drive :
 It is used in oil industries for long distance
 It is also aaplicable in large crushers in which high power is required to
break large stones.
 It is also used in conveyer belt.

26. 26
5.PROGRAMMABLE LOGIC CONTRLLER
5.1 Basics of PLC:
A programmable logic controller (PLC), also referred to as a
programmable controller, is the name given to a type of computer commonly
used in commercial and industrial control applications.
The basic elements of a PLC include input modules or points, a central
processing unit (CPU), output modules or points, and programming device.
The type of input modules or points used by a PLC depends upon the
types of input devices used. Some input modules or points respond to digital
inputs, also called discrete inputs, which are either on or off. Other modules
or inputs respond to analog signals. These analog signals represent machine
or process conditions as a range of voltage or current values. The primary
function of a PLC’s input circuitry is to convert the signals provided by these
various switches and sensors into logic signals that can be used by the CPU.
5.2 Parts of PLC Panel:
 Power Supply :
Power Supply is used to supply 24V to the whole panel. 24V is obtained
by converting external 230 V supply

27. 27
 CPU :
The CPU evaluates the status of inputs,
outputs, and other variables as it executes a
stored program. The CPU then sends signals
to update the status of outputs.
 Bus Module :
This is a supply voltage distribution module for 24VDC with power on
indication. It is available with either 20 or 40 terminals. These terminals
are mounted on the PCB and packed in green profile to be mounted on
DIN rail. This module helps to make clean power distribution with better
panel aesthetics & easy maintenance for the panel.

28. 28
 Analog I/O Module :
This is used for transmitting analog signal to communication interface.
This unit acts as a slave and can be multi dropped when multiple units are
required for multiple signals. Maximum of 31 units can be multi dropped.
The communication protocol used is MODBUS. The slave addresses can
be selected from master device.
The supply voltage available is 230VAC/110VAC. The units are available
in DIN rail mounted plastic enclosures.
 Digital I/O Module :
This DIN rail mounted unit is used for conversion of temperature into
equivalent 8 bit digital output. The temperature sensor input is PT-100
RTD & digital output is 24VDC with 8-bit resolution. Supply voltage is
24VDC & housed in plastic enclosures. Multiple units can be paralleled
for more than one sensor.
No analog input is required for reading the temperature & can be done
with digital inputs & hence cost effective.
 Optocouplers :
Optocouplers typically come in a small 6-pin or 8-pin IC package, but are
essentially a combination of two distinct devices: an optical transmitter,
typically a gallium arsenide LED (light-emitting diode) and an optical
receiver. The two are separated by a transparent barrier which blocks any
electrical current flow between the two, but does allow the passage of

29. 29
light. Optocouplers are essentially digital or switching devices, so they
are best for transferring either on-off control signals or digital data.
Analog signals can be transferred by means of frequency or pulse-width
modulation.
5.3 Testing of PLC Panel :
There are four major steps in panel testing
 Visual inspection : In this stage we have to check all the
connection as per given drawing. We have to check whether any
part is missing or not.All electrical parameter of all equipment
used in the panel.
 Continuity : Continuity test is for to check all the wires are well
connected or not. It is also useful for checking continuity of
wire.
 High Voltage Test : After checking all the continuity we go for
H.V. test in which we give a high voltage between one of the
part of panel and body of panel. This is to test whether there is
shorting between part of panel and body as well as leakage
current through insulation which should not be greater than
given value.
5.4 Additional Advantages Of PLCs:
• Smaller physical size than hard-wire solutions.
• Easier and faster to make changes.
• PLCs have integrated diagnostics and override functions.
• Diagnostics are centrally available.
• Applications can be immediately documented.
• Applications can be duplicated faster and less expensively.

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6. Research And Development Department:
6.1 Introduction:
Research and development is the main department in any industry. Every
customer has his own requirements. So RnD department figures out the circuit
diagram for the project. The circuit diagram should be manufacturable i.e. all
the components should be easily available and obviously the product should be
profitable. Accordingly changes are made in the design of the product. Then the
design is released in the further respective department.
6.2 Product development cycle:
1. Customer submits the application of his requirements.
2. If any, specific requirements of the customer are given special attention.
3. It is seen that are there any other customers in the market with the almost
same requirements. If any, the customer is told to negotiate with his
requirements so that the same product can be sold to more than one
customer. This saves the production time and efforts.
4. Then final drafting of specifications is done.
5. Tentative cost is suggested to the customers.
6. It is tried to have a more reliable and less complex product.
7. With the knowledge of all above, the final circuit diagram is prepared.
8. Mechanical requirements of the product are given attention e.g. size and
weight of the product should be as suggested by the customer.
9. PCB is designed.
10.Components are so chosen that quality of product and profitability of
industry are both maintained.
11.Once components are chosen, they are assembled to have a desired
design.
12.In this way the product is completed. First 2 or 3 modules are called as
‘Prototype Module’. These prototype modules are tested first. If all the
tests give positive results then more number of products are manufactured
in the same manner. Otherwise faults are detected in each module and
then they are repaired accordingly.

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13.Research and development decides the testing plan for every product. It
differs from product to product but normally it consists of continuity test,
HV test, function test, mechanical test etc.
14.Now all the tests are performed on Zero series. Zero series is the group of
25-50 modules.
15.If required field trial is taken i.e. some of the modules are taken to the
field and they are checked for the temperature, humidity etc conditions on
the field.
16.If all the steps are followed by the product and it is giving positive
response then the product is finally released.
6.3 R&D products:
 AC-DC Converters of different ratings
 AC-DC Converters of different ratings
 Voltage transducers
 Earth leakage relays
 Interface modules