a training report on classic control and PLC basics contains : classic control basics PLC basics timers contractors and relays sensors

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A
TRAINING REPORT ON CLASSIC CONTROL AND
PLC BASICS
SUBMITTED BY
Ahmed Abd El-Nasser Mohamed Aboelhasan
MTE Level 300

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ABSTRACT
Nowadays, the application of PLC is widely known and use in this digital world PLC’s
application is obviously applied at the industrial sector. Normally, the PLC’s that have
been used at the industrial field is usually to control a mechanical movement either of
the machine or heavy machine in order to create an efficient production and accurate
signal processing.
In during the training period, we learn about Classic Control and the PLC and
Automation system, programming of plc, different type of plc manufactures company,
hardware and software of plc.

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Table of Contents
Abstract...........................................................................................................................................2
Automation .....................................................................................................................................4
Basics of Classic Control..............................................................................................................5
Sensors.....................................................................................................................................7
Relay.........................................................................................................................................8
Timers.......................................................................................................................................9
PLC..................................................................................................................................................9
Criteria and Types of PLCS........................................................................................................10
PLC operations and scan cycle..............................................................................................11
Ladder logic programming......................................................................................................12
Applications..................................................................................................................................13
PLC components .........................................................................................................................14
Motor drive and connections .....................................................................................................15
References....................................................................................................................................16

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What is Automation?
Automation is the use of control systems such as computers, controllers to control industrial
machinery and processes, to optimize productivity in the production of goods and delivery of
services. Automation is a step beyond mechanization. Whereas mechanization provides human
operators with machinery to assist them with the muscular requirements of work, automation
greatly decreases the need for human sensory and mental requirements.
Advantages of Automation:
1. Replacing human operators in tasks that involve hard physical or monotonous work Also task
done in dangerous environments.
2. Performing tasks that are beyond human capabilities of size, weight, speed, endurance, etc.
3. Automation may improve in economy of enterprises, society or most of humanity.
Disadvantages of Automation:
1. Current technology is unable to automate all the desired tasks.
2. The research and development cost of automating a process may exceed the cost saved by
the automation itself.
3.The automation of a new product or plant requires a huge initial investment in comparison with
the unit cost of the product.
Any process consists of:
1.Application (operative part).
2.Control system (Action coordinator).
Control system:
is a device or set of devices to manage, command, direct or regulate the behavior of other
devices or systems (open loop, closed loop).

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Components of control system:
 Panel
 AC or DC sources
 Circuit breakers
 Fuses
 Switches
 Contactors & Relays
 Timers
 Counters
 Sensors
 Over load
Panel: is a flat, often vertical, area where control or monitoring instruments are displayed or it
is an enclosed unit that is the part of a system.
Electrical Sources:
AC DC
 Single phase (L & N) 220v
 Three phases (R, S, T) or (L1, L2,
L3) or (X, Y,Z) beside N,E
 Always use 24v
 greatly reducesthe wiring cost
to almost half the original cost
Line/Wiring Diagram:
Control circuit: lowpower lines and circuits
Power circuit: High power lines and circuits
So:
 Thin line it means a wire holds low power ‘Control line’
 Thick line it means a wire holds high power ‘Power line’
 Blue wire it is connected with 24v
 Red wire it is connected with 110v or 220v
 Black wire it is connected with ground, zero volt
 Orange wire it means that the electricity he carries is not from this cabin, but from
another cabin

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Switches:
 Single pole Single throw ON/OFF switch  SPST SWITCH
 Double pole Single throw ON/OFF switch  DPST SWITCH
 Single pole Double throw ON/ON switch  SPDT SWITCH
 Double pole Double throw ON/ON switch  DPDT SWITCH
 Single pole 5 Ways switch (2P 5W), (3P 4W)  SP5W SWITCH
Switch Ratings:
 Rating current (Ampere): Max current throw between contact of switch without making short.
 Rating voltage (Voltage): Max voltage applied between without making a spark
 Making & Breaking current: Max current in case opening and closing switch
 Number of switching (Frequency rating): Number opening and closing switch
Manually operated switches:
 Toggle switch
 Rocker switch
 Push button switch
 Slide switch
 Rotating selectable switch
 Keylock switch
 Knife switch
 Manual motor starter
 Limit switch
 Pressure switch
 Level switch
Electronic switches:
Detect target without physical contact and it’s called Sensors.

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Sensors:
is a device that converts the physical condition into an electrical signal to the PLC.
 Proximity sensor
 Photo sensor
 Ultrasonic sensor
 Temperature sensor
 Electronic level sensor
 Electronic flow rate sensor
 Electronic pressure sensor
Proximity sensor:
 2 types (inductive, capacitive)
 2 wire DC or non-polarized NO, NC output
 3 wire type DC polarized NO, NC output
 4 wire type, multifunction, programmable DC polarized NO, NC output, PNP, NPN
Applications:
 Detecting the presence of a broken drill bit
 Detecting milk in cartons
 Controlling fill level of solids in a bin
 Detecting presence of can and lid
Photo electric sensor:
Use a modulated light beam that is either broken or reflected by the target.
 2 wire DC or non-polarized NO, NC output
 3 wire type DC polarized NO, NC output
 5 wire technique DC or AC, Relay output
 Analogue technique
Applications:
 Counting cans
 Detecting persons
 End of roll detecting
 Controlling parking gate
Ultrasonic sensor:
Uses transducers to send and receive high frequency sound signals to detect the presence of
an object.
Applications:
 Quality control
 Anti-collision
 Level measurements in (tanks, bottles, vessels)

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Output control system:
Output device Quantity produced Input
Motors Rotational motion Electrical
Pump Rotational motion + product
displacement
Electrical
Piston Linear motion/pressure Hydraulic/pneumatic
Solenoid Linear motion/pressure Electrical
Heater Heat Electrical
Valve Orifice variation Electrical/hydraulic/pneumatic
Relay Elect. switching Electrical
Relay:
Controlling very high power at the output using a very low power of control signal at the
input.
Input control coil: very low [voltage, current and power]
Output contact: very high [voltage, current and power]
Three phase contactors:
When a relay is used to switch a large amount of electrical power through its contacts it is
designated by a special name contactor. Contactors typically have many contacts.
Overload relay:
overload relays are economic electromechanical protection devices for the main circuit. They offer
reliable protection for motors in the event of overload or phase failure.
Circuit breaker:
is an automatically operated electrical switch designed to protect an electrical circuit from damage
caused by excess current from an overload or short circuit

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Timers:
It is a tool that can control operating times and disconnect electric motors.
Types:
1.Based on configuration:
 Timer with motor
 Electric timer
 Pneumatic timer
2.Based on function:
 ON delay timer
 OFF delay timer
 Flasher timer
 Programmable timer
 Mercury timer
Programmable Logic Controller (PLC):
is a digital computer used for automation of industrial processes, such as control of machinery on
factory assembly lines It is a solid-state user programmable control system with functions to control
logic, sequencing, timing, arithmetic data manipulation and counting capabilities. It can be viewed as
an industrial computer that has a central processor unit, memory, input output interface and a
programming device. The central processing unit provides the intelligence of the controller. It
accepts data, status information from various sensing devices like limit switches, proximity switches,
executes the user control program stored in the memory and gives appropriate output commands to
devices such as solenoid valves, switches etc.
A constant demand for better and more efficient manufacturing and process machinery has led to
the requirement for higher quality and reliability in control techniques. With the availability of
intelligent, compact solid-state electronic devices, it has been possible to provide control systems
that can reduce maintenance, down time and improve productivity to a great extent. One of the latest
techniques in solid state controls that offers flexible and efficient operation to the user is
programmable controllers.
Features of PLC:
 It is designed for multiple inputs and output arrangements, extended temperature ranges,
immunity to electrical noise, and resistance to vibration and impact.
 Almost any production process can greatly enhance using this type of control system, the
biggest benefit in using a PLC is the ability to change and replicate the operation or process
while collecting and communicating vital information.

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Types of PLC Programming logic controller (PLCs):
has several types: Based on the size of the module and it can be classified according to is working.
Based on Size:
 Micro PLC or Small PLC
 Medium PLC or Mini
 Large PLC or Rack
Classified according to its Output working:
1. Relay based: This type of PLC is used for general purpose application.
2. Transistor based: This type of PLC is used for High speed application.
3. SCR based: This type of plc is used for heavy load switching.
DifferentPLC Manufactures:
 Siemens
 FATEK
 Delta
 Allen Bradley
 Mitsubishi
 Omron
 ABB
 Panasonic
 GE Fanuc
 LG
Criteria of choosing PLC:
 Cost
 No. of I/OS
 Memory Capacity
 Processing Speed of CPU
 CPU Capabilities
 No. of Timer, Counters
 Interface Module
 Networking & Communication Facility

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PLC operation:
There are four basic steps in the operation of all PLCS which continually take place in a repeating
loop.
1. Input Scan: Detects the state of all input devices that are connected to the PLC.
2. Program Scan: Executes the user created program logic.
3. Output Scan: Energizes or de-energize output devices that are connected to the PLC.
Depending on the PLC design, this process of updating the output devices may be done at
the end of program execution or updated immediately upon execution of its corresponding
logic statement in the user program
4. Housekeeping: This step includes communications with programming terminals, internal
diagnostics etc.
PLC scan cycle:
The completion of a cycle of the controller is called a Scan. The scan time needed to complete a full
cycle by the controller gives the measure of the speed of execution for the PLC.
SCAN TIME taken by PLC to execute these three steps (Checking Input status, Executing Program,
Updating Output Status) is denoted by its scan time.

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Ladder logic:
is one form of drawing electrical logic schematics, and is a graphically language very popular for
programming PLCS. Ladder logic was originally invented to describe logic made from relays. The
name is based on the observation that programs in this language resemble ladders, with two vertical
“rails” and a series of horizontal “rungs” between them.
A program in ladder logic, also called a ladder diagram, is similar to a schematic for a set of relay
circuits. Ladder logic is widely used to program PLCS, where sequential control of a process or
manufacturing operation is required. Ladder logic is useful for simple but critical control systems, or
for reworking old hardwired relay circuits.
Ladder diagram for Motor starter Ladder Logic Latch

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Applications:
 One-phase motor drive running and standing from one place
 Three-phase motor drive running and standing from one place
 Three-phase motor drive running and standing from 2 different places
 Three-phase motor drive running when pushing 2 buttons together
 The control circuit for a motor that operates with an on switch and another off switch and has
a double switch for short periods of operation
 Control circuit for a motor that works in both directions directly without stopping
 Operation of a three-phase motor by connecting the Delta / Star
 The control circuit in two engines The first runs a vehicle that runs on a walk between two
points and when it reach point B stops for 3 seconds and the second engine works and it is a
pump motor to put fluid inside the vehicle then stops the pump motor and then the vehicle
returns to point A.
 Motor starter with ladder
 Latch with ladder (different ways)

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References:
 Training notes
 Training applications
 https://ladderlogicworld.com ‘photos source’
 https://instrumentationtools.com ‘photos source’

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PLC components:
 Power supply
 CPU
 I/O modules
Power supply:
 Input 220vAC to output 24vDC
 Feed the CPU and I/O modules
CPU:
 Contains the program and control all i/o
 Contains memory card, run/stop/reset button, lamps:
Name Color Couse
SF RED Error in hardware or software
MAINT Yellow Need to maintenance
DC5V Green 5v for CPU exist
Force Yellow There some forces on signals
Run Green It’s work
Stop Yellow Stopped
CPU:
Input Output
Analog Digital Analog Digital
It takes values in mV
- mA and convert it to
digital Ex: some
sensors.
It takes only 2 signals
open or close Ex:
Switches – sensors.
It transmits signals in
mV or mA from CPU
to the production line
Ex: control valve.
It gives only 0v or 24 v
to the relay, valve,
contactor.
Power supply   I/O modules
CPU

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Motor drive and connections:
DOL (direct on line):
The most famous way we use it in small motors which doesn’t need change in speed.
Adv Dis adv
 Low cost
 It gives high torque
 Motor startup current very high
 Gives high torque
 Not suitable with high ability motors
Star/Delta connection:
We connect the motor star or delta according
to data on nameplate.
So, to improve the first method we can start
the motor with star connection for some time
and then convert to delta connection.
Adv Dis adv
 Startup current less with 30%
 Torque less with 25%
 The moment of conversion between the
two-connection a rise occurs at current
Soft starter:
It’s better than the first and the second method we solved the problems with soft starter.
Where controls voltage, startup current, torque but it’s very expensive way
VFD (variable speed drive):
Contain 2 parts one converts the AC to DC and the other convert DC to AC again but with different
frequency.
Change speed or frequency, and we use it with applications which need to change in speed and
frequency.