This is report of my internship at SERVICE INDUSTRIES (GUJRAT). I got traning related of "PLC" specially (MITSUBISHI PLC). This report contains basics of "PLC" hardware & programming.

1. 2015
IQTADAR ALI GILANI
UNIVERSITY OF GUJRAT (PAKISTAN)
11/9/2015
Internship Report

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TABLE OF CONTENTS PAGE
1: INTRODUCTION 2
2: DEPARTMENT 3
3: INSTRUCTOR 4
4: BASIC STAR AND DELTA CONNECTIONS 4
5: 3 φ INDUCTION MOTOR STARTER (STAR TO DELTA) 6
6: CONTROL OF 3 φ INDUCTION MOTOR (FORWARD AND REVERSE) 10
7: INTRODUCTION TO PLC 12
8: PLC LANGUAGES, VENDORS & FEATURES 12
9: PLC TYPES 13
10: PLC HARDWARE 14
11: PLC PROGRAMMING 18
12: LADDER LOGIC 18
13: BASIC DIGITAL LOGIC FUNCTIONS 19
14: PLC IN SERVICE INDUSTRIES (TYRE DIVISION SECTION) 22
15: PROGRAMMS 23
16: AUTOMATION OF PRODUCT PACKAGING 23
17: AUTOMATION OF STORAGE DOOR 27
18: VARIABLE FREQUENCY DRIVE (VFD) 29
ENGR. SULAMAN ZEESHAN IQBAL

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INTRODUCTION
It is pleasure and honor for me, that I spent my precious time as an interne in
Service Industries Private Limited Gujrat (PAKISTAN). It was really practical
and wonderful experience. I wanted to get traning and experience related to PLC
and Service industry is one of those industries in which 70 persent machinery is
controlled with the help of PLC. So, I got traning and now I have sound knowledge
and experience related to PLC.
HISTORY OF INDUSTRY
Ch. Nazar Muhammad, Ch. Muhammad Hussain and Ch. Muhammad Saeed
started their business in 1941 from the manufacturing of hand bags and they started
the production of footwear in 1954.
Products of SERVIS
 Leather Shoes
 Sports Shoes
 Canvas Shoes
 Rubber Sandals
 Rubber Slippers
 Safety Shoes
 Footwear for Defense Forces
 Tyres and Tubes for Bicycles, Motor Bikes and Cars
Servis Shoes Brands
 Don Carlos (N Dure, Maximus, Breezers, Classic)
 Cheetah
 Calza
 Liza
 Toz
 Skooz

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General Manager
Ghulam Ahmad Cheema is present general manager of Service Industries limited.
DEPARTMENT
Tyre Division (Electrical)
I worked in Electrical department of tyre division section. All the staff of electrical
department was very co-operative with me especially my instructor. In electrical
department faults related to electrical part of machinery is resolved. Such as, if the
electrical part of some machinery is out of order such as Fuse, Circuit Breaker,
relay, timer, motor winding and etc then technicians solve the problem. The
hierarchy of people in electrical department is follows:
MANAGER
SENIORENGINEER
SENIORSUPERVISIOR
SHIFT ENGINEER
SHIFT INCHARGE
WORKERS ANDTECHNICIANS

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INSTRUCTOR
My instructor name was Engr. Sulaman. He is expert in plc hardware and
programming. He has also excellent management skills. He started to teach me
from basics and then in very short time, I understood and studied all essentials of
PLC hardware and programming. Now I am able to understand and read complex
PLC programs of large machines such as ULT tyre section press machine and etc.
My instructor also guided me how to manage staff members as well as office work.
To solve the big issues such as related to PLC, technicians’ refer this to Engr.
SULAMAN. Sir SULAMAN which has great experience solves the problems in
minutes and save a lot of time. In this way they manage all things in efficient way.
BASIC STAR AND DELTA CONNECTIONS
STAR CONNECTION
In this kind of interconnection, the starting ends or finishing ends (Similar ends) of
three coils are connected together to form the neutral point. Or Star Connection is
obtained by connecting together similar ends of the three coils, either “Starting” or
“finishing”. The other ends are joined to the line wires. The common point is
called the neutral or Star Point, which is represented by N.
DELTA CONNECTION
In this system of interconnection, the starting ends of the three phases or coils are
connected to the finishing ends of the coil. Or the starting end of the first coil is
connected to the finishing end of the second coil and so on (for all three coils) and
it looks like a closed mesh or circuit Three wires are taken out from three junctions
and the all outgoing currents from junction assumed to be positive. In more clear
words, all three coils are connected in series to form a close mesh or circuit.

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IN STAR CONNECTION
VL = √3 VPH or VL = √3 EPH
Line Current = Phase Current
IL = IPH
Total Power = P = 3 x VPH x IPH x CosФ OR P = √3 x VL x IL x CosФ
IN DELTA CONNECTION
VL = VPH
I.e. in Delta connection, the Line Voltage is equal to the Phase Voltage.
IL = √3 IPH
Total Power = P = 3 x VPH x IPH x CosФ OR P = √3 x VL x IL x CosФ

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3 φ INDUCTION MOTOR STARTER (STAR TO DELTA)
WHY WE USE STAR TO DELTA?
Most induction motors are started directly on line, but when very large motors are
started that way, they cause a disturbance of voltage on the supply lines due to
large starting current surges. To limit the starting current surge, large induction
motors are started at reduced voltage and then have full supply voltage reconnected
when they run up to near rotated speed. During starting the motor windings are
first connected in star connection this causes the reduction of voltages by 3. This
also reduces the torque by 3. After a period of time the windings are reconfigured
as delta and the motor runs normally.
CIRCUIT DIAGRAM OF STAR –DELTA STARTER

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WORKING
 The main circuit breaker serves as the main power supply switch that
supplies electricity to the power circuit.
 The main contactor connects the reference source voltage R, Y, B to the
primary terminal of the motor U1, V1, W1.
 In operation, the Main Contactor (KM3) and the Star Contactor (KM1) are
closed initially, and then after a period of time, the star contactor is opened,
and then the delta contactor(KM2) is closed. The control of the contactors is
by the timer (K1T) built into the starter. The Star and Delta are electrically
interlocked and preferably mechanically interlocked as well.

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Controlling the interchanging star connection and delta connection of an AC
induction motor is achieved by means of a star delta or wye delta control circuit.
The control circuit consists of push button switches, auxiliary contacts and a timer.
CONTROL CIRCUIT OF STAR-DELTA STARTER

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WORKING
 The ON push button starts the circuit by initially energizing Star Contactor
Coil (KM1) of star circuit and Timer Coil (KT) circuit.
 When Star Contactor Coil (KM1) energized, Star Main and Auxiliary
contactor change its position from NO to NC.
 When Star Auxiliary Contactor (1)( which is placed on Main Contactor coil
circuit )became NO to NC it’s complete The Circuit of Main contactor Coil
(KM3) so Main Contactor Coil energized and Main Contactor’s Main and
Auxiliary Contactor Change its Position from NO To NC. This sequence
happens in a friction of time.
 After pushing the ON push button switch, the auxiliary contact of the main
contactor coil (2) which is connected in parallel across the ON push button
will become NO to NC, thereby providing a latch to hold the main contactor
coil activated which eventually maintains the control circuit active even after
releasing the ON push button switch.
 When Star Main Contactor (KM1) close its connect Motor connects on
STAR and it’s connected in STAR until Time Delay Auxiliary contact KT
(3) become NC to NO.
 Once the time delay is reached its specified Time, the timer’s auxiliary
contacts (KT)(3) in Star Coil circuit will change its position from NC to NO
and at the Same Time Auxiliary contactor (KT) in Delta Coil Circuit(4)
change its Position from NO To NC so Delta coil energized and Delta Main
Contactor becomes NO To NC. Now Motor terminal connection change
from star to delta connection.
 A normally close auxiliary contact from both star and delta contactors
(5&6)are also placed opposite of both star and delta contactor coils, these
interlock contacts serves as safety switches to prevent simultaneous
activation of both star and delta contactor coils, so that one cannot be
activated without the other deactivated first. Thus, the delta contactor coil
cannot be active when the star contactor coil is active, and similarly, the star
contactor coil cannot also be active while the delta contactor coil is active.

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 The control circuit above also provides two interrupting contacts to
shutdown the motor. The OFF push button switch break the control circuit
and the motor when necessary. The thermal overload contact is a protective
device which automatically opens the STOP Control circuit in case when
motor overload current is detected by the thermal overload relay, this is to
prevent burning of the motor in case of excessive load beyond the rated
capacity of the motor is detected by the thermal overload relay.
 At some point during starting it is necessary to change from a star connected
winding to a delta connected winding. Power and control circuits can be
arranged to this in one of two ways – open transition or closed transition.
CONTROL OF 3 φ INDUCTION MOTOR (FORWARD AND
REVERSE) POWER DIAGRAM

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CONTROL OF 3 φ INDUCTION MOTOR (FORWARD AND
REVERSE) CONTROL DIAGRAM

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INTRODUCTION TO PLC
DEFINATION 1
It is a programmable interface between input devices like push buttons, limit
switches etc and final control element like actuators, relays, motors, solenoid
valves and status indicating output devices like lamp, led, hooters and etc.
DEFINATION 2 (BY NATIONAL ELECTRICALMANUFACTURE
ASSOCIATION_)
PLC is "A digitally operating electronic apparatus that uses a programmable
memory for internal storage of instructions for implementing specifics functions,
such as logic sequencing, timing, counting, and arithmetic, to control, through
digital or analogue input/output modules, various machines or processes".
PLC LANGUAGES, VENDORS & FEATURES
PLC LANGUAGES
 Ladder diagram (mostly use every where)
 Functional block diagram (FBD)
 Sequential functional chart (SFC)
 Structured text language (ST)
PLC VENDORS
 Siemens
 Allen bradley
 Schneider
 Beckhoff
 Mitsubishi
 Messing
 Ge – Fanuc
 Omron

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PLC FEATURES
 Sequential logic solver
 Bit operation
 Data transfer
 Text handling
 PID calculation
 Subroutines
PLC TYPES
COMPACT
 In Compact PLC CPU unit, Communication Port, Power Supply unit, Inputs
and Outputs all are mounted on a single board.
 I/O capacity of Compact PLC is less than I/O capacity of Modular PLC.
 Generally used for small applications such as Hydraulic press machine, any
Special Purpose machine (SPM), etc.
Modular PLC
 In Modular PLC consisting separate parts as described below:-
1. Base Rack,
2. Power Supply Module,
3. CPU Module,
4. Input Modules,
5. Output Modules,
 I/O capacity of Modular PLC is more than I/O capacity of Compact PLC.
 Generally used for large Application Such as Plant Automation, Power Plant
Handling, etc.
 In Modular PLC there is also some Small PLC ( i.e. Nexgen 2K, Nexgen
5K)available which we can use in Small applications.

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PLC HARDWARE
I/O SECTION
The I/O section establish the interfacing between physical devices in the real world
outside the PLC and the digital arena inside the PLC.
The input module has bank of terminals for physically connecting input devices,
like push buttons, limit switches etc. to a PLC. the role of an input module is to
translate signals from input devices into a form that the PLC's CPU can
understand.
The Output module also has bank of terminals that physically connect output
devices like solenoids, motor starters, indicating lamps etc. to a PLC. The role of
an output module is to translate signals from the PLC's CPU into a form that the
output device can use.

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The tasks of the I/O section can be classified as:
 Conditioning
 Isolation
 Termination
 Indication
CPU SECTION
The Central Processing Unit, the brain of the system is the control portion of the
PLC. It has three Subparts.
 Memory System
 Processor
 Power Supply
MEMORY SYSTEM:-
The memory is the area of the CPU in which data and information is stored and
retrieved.The total memory area can be subdivided into the following four
Sections.
 I/O IMAGE MEMORY
The input image memory consists of memory locations used to hold the ON or
OFF states of each input field devices, in the input status file.
The output status file consists of memory locations that stores the ON or OFF
states of hardware output devices in the field. Data is stored in the output status file
as a result of solving user program and is waiting to be transferred to the output
module's switching device.
 DATA MEMORY
It is used to store numerical data required in math calculation, bar code data etc.

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 USER MEMORY
It contains user's application program.
 EXECUTIVE MEMORY
It is used to store an executive program or system software . An operating system
of the PLC is a special program that controls the action of CPU and consequently
the execution of the user's program. A PLC operating system s designed to scan
image memory, interprets the instruction of user's program stored in main memory,
and executes the user's application program the operating system is supplied by the
PLC manufacturer and is permanently held in memory.
PROCESSOR
The processor, the heart of CPU is the computerized part of the CPU in the form
of Microprocessor / Micro controller chip. It supervises all operation in the system
and performs all tasks necessary to fulfill the PLC function.
 It reads the information i.e status of externally connected input devices with
input module.
 It stores this information in memory for later use.
 It carries out mathematical and logic operations as specified in application
program.
 After solving the user's program, it writes the result values in the memory.
 It sends data out to external devices like output module, so as to actuate field
hardware.
 It performs peripheral and external device communication.
 It performs self diagnostics.

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POWER SUPPLY
The power supply provides power to memory system, processor and I/O Modules.
 It converts the higher level AC line Voltage to various operational DC
values.
 For electronic circuitry.
 It filters and regulates the DC voltages to ensure proper computer
operations.
Programmer/Monitor:-
The Programmer/Monitor (PM) is a device used to communicate with the circuits
of the PLC.The programming unit allows the engineer/technicians to
enter the edit the program to be executed.
In its simplest form it can be hand-held device with membrane keypad for
program entry and a display device (LED or LCD) for viewing program steps of
functions.
More advanced systems employ a separate industrial terminal or personal
computers with type-writer type keyboard and CRT monitors. With the help of
proprietary software, it allows programmer to write, view and edit the program and
download it into the PLC. It also allows user to monitor the PLC as it is running
the program. With this monitoring systems, such things as internal coils, registers,
timers and other items not visible externally can be monitored to determine proper
operation. Also,internal register data can be altered, if required. to fine tune
program operation while debugging communication between PM and PLC is done
via a cable connected to a special programming port on PLC. connection to the
personal computer can be through a serial port or from a dedicated card installed in
the computer.

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PLC PROGRAMMING
DIGITAL I/O
Inputs are push buttons, limit switches, photo sensors and ets. common out put
devices include relays, motor starters and solenoid valves.
ANALOG I/O
Inputs are transmitters used for sensing various parameters. Common output
signals are (motor speed, valve position, air pressure and etc).
LADDER LOGIC
"LADDER" DIAGRAMS
Ladder diagrams are specialized schematics commonly used to document industrial
control logic systems. They are called "ladder" diagrams because they resemble a
ladder, with two vertical rails (supply power) and as many "rungs" (horizontal
lines) as there are control circuits to represent. If we wanted to draw a simple
ladder diagram showing a lamp that is controlled by a hand switch, it would look
like this:
The "L1" and "L2" designations refer to the two poles of a 120 VAC supply, unless
otherwise noted. L1 is the "hot" conductor, and L2 is the grounded ("neutral")
conductor.

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BASIC DIGITAL LOGIC FUNCTIONS
AND FUNCTION
OR FUNCTION

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NOT FUNCTION
NAND FUNCTION
NOR FUNCTION

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Exclusive-OR function
If we wish to invert the output of any switch-generated logic function, we must use
a relay with a normally-closed contact. For instance, if we want to energize a load
based on the inverse, or NOT, of a normally-open contact, we could do this:
We will call the relay, "control relay 1," or CR1. When the coil of CR1 (symbolized
with the pair of parentheses on the first rung) is energized, the contact on the
second rung opens, thus de-energizing the lamp. From switch A to the coil of CR1,
the logic function is noninverted. The normally-closed contact actuated by relay
coil CR1 provides a logical inverter function to drive the lamp opposite that of the
switch's actuation status.

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PLC IN SERVICE INDUSTRIES (TYRE DIVISION SECTION)
In tyre division section of Service Industries all machines are working at
MITSUBISHI’S plc modules (FX2N & FX3U). I got training of FX2N.
MITSUBISHI FX2N & FX3U

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PROGRAMMS
AUTOMATION OF PRODUCT PACKAGING
Product packaging is one of the most frequent cases for automation in industry. It
can be encountered with small machines (ex. packaging grain like food products)
and large systems such as machines for packaging medications. Example we are
showing here solves the classic packaging problem with few elements of
automation. Small number of needed inputs and outputs provides for the use of
CPM1A PLC controller which represents simple and economical solution.
By pushing START key you activate Flag1 which represents an assisting flag
(Segment 1) that comes up as a condition in further program (resetting depends
only on a STOP key). When started, motor of an conveyor for boxes is activated.
The conveyor takes a box up to the limit switch, and a motor stops then (Segment
4). Condition for starting a conveyor with apples is actually a limit switch for a

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box. When a box is detected, a conveyor with apples starts moving (Segment 2).
Presence of the box allows counter to count 10 apples through a sensor used for
apples and to generate counter CNT010 flag which is a condition for new
activation of a conveyor with boxes (Segment 3). When the conveyor with boxes
has been activated, limit switch resets counter which is again ready to count 10
apples. Operations repeat until STOP key is pressed when condition for setting
Flag1 is lost. Picture below gives a time diagram for a packaging line signal.

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LADDER DIAGRAM

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AUTOMATION OF STORAGE DOOR
Storage door or any door for that matter can be automated, so that man does not
have to be directly involved in their being opened or closed. By applying one
three-phased motor where you can change direction of its movement, doors can be
lifted up and lowered back down. Ultrasonic sensor is used in recognizing presence
of a vehicle by the doors, and photo-electric sensor is used to register a passing
vehicle. When a vehicle approaches, the doors move up, and when a vehicle passes
through the door (a ray of light is interrupted on photo-electric sensor) they lower
down.

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By setting a bit IR000.00 at the PLC controller input where ultrasonic sensor is
connected, output IR010.00 (a switch is attached to this output) is activated, so that
a motor lifts the doors up. Aside from this condition, the power source for lifting
the doors must not be active (IR010.01) and the doors must not be in upper
position already (IR000.02). Condition for upper limit switch is given as normally
closed, so change of its status from OFF to ON (when doors are lifted) will end a
condition for bit IR010.00 where power source for lifting the doors is (Segment 1).
Photo-electric switch registers a vehicle that passes by, and sets flag IR200.00.
DIFD instruction is used. This instruction is activated when a condition that
precedes it changes status from ON to OFF. When a vehicle passes through a door,
it interrupts a ray and bit IR000.01 status changes from ON to OFF (Segment 2).
By changing status of an assisting flag from OFF to ON a condition for lowering a
door is executed (Segment 3). Aside from this condition, it is necessary that a unit
power source for lifting a door is turned off, and that door is not in lower position
already. Bit which operates this power source for lowering, IR010.01 is automatic,
so doors are lowered until they come to the bottom limit switch which is
represented in a condition as normally closed. Its status change from OFF to ON
interrupts a condition of the power source for lowering doors. With oncoming new
vehicle, cycle is repeated.

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LADDER DIAGRAM

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VARIABLE FREQUENCY DRIVE (VFD)
A Variable Frequency Drive (VFD) is a type of motor controller that drives an
electric motor by varying the frequency and voltage supplied to the electric motor.
Frequency (or hertz) is directly related to the motor’s speed (RPMs). In other
words, the faster the frequency, the faster the RPMs go. If an application does not
require an electric motor to run at full speed, the VFD can be used to ramp down
the frequency and voltage to meet the requirements of the electric motor’s load. As
the application’s motor speed requirements change, the VFD can simply turn up or
down the motor speed to meet the speed requirement.
A VFD is used extensively in modern facilities to save energy on mechanical
systems, such as motors, pumps, etc. Selected to match motor curves to ensure
speed and loads are matched, VFDs can help save motor energy by allowing for
variable flow of air, water, etc., based on the demands and needs of a particular
site. This is accomplished by converting the fixed frequency of incoming
alternating current (AC) voltage to direct current (DC) and then reconverting it
back to AC voltage by varying the frequency at which the insulated gate bipolar
transistors (IGBTs) are gated on and off.
WORKING
A VFD operates by converting the input sinusoidal AC voltage to DC voltage and
then back to AC voltage. This conversion occurs by using either silicon-controlled
rectifiers (SCRs) or IGBTs. The DC voltage is switched using IGBTs to create an
AC output voltage (called the inverter). The IGBT can switch on and off to create
an AC voltage waveform that delivers power to the motor. The IGBTs create an
AC waveform by using pulse width-modulated (PWM). The frequency at which
the switching occurs, which varies from manufacturer to manufacturer, is called
“carrier frequency.”
A typical 6-pulse VFD has six diodes as a front-end bridge rectifier that converts
AC to DC. VFDs can also have 12 diodes two sets per phase (2 × 2 × 3 = 12 pulse)
or 18 diodes three sets per phase (3 × 2 × 3 = 18 pulse) and so on .One set of
diodes is supplied by a Delta-Y transformer to create a phase shift on the AC side
between the two rectifiers to reduce harmonics reflected back to the source.

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6-PULSE VFD
A 6-pulse VFD develops the output DC voltage by taking each phase of the AC
source and installing one set of diodes to gate on and off A 6-pulse VFD is most
commonly used in the building system. Typical current total harmonic distortion
(THD) back to the source can be as high as 35% at the input terminals of the VFD.
You can install an inline inductor to reduce the reflected harmonics back to the
point of coupling. The inductor reduces the current distortion and thus the voltage
distortion at the source. The input line inductors are typically 3% to 5%
impedance. Base the selection of the inductor on harmonic evaluation of the
electrical system at the building, impact of voltage drops across the inductor, and
impact of power factor to the building electrical system.
The impact of harmonics should take into account available fault current (i.e., the
stiffness of the electrical system).