automation of series genr

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AUTOMATION OF SERIES GENERATOR USING PLC

I. INTRODUCTION

In the recent past, Automation techniques have become one of the effective strategies in the modern

manufacturing process. Most of the manual operations involved in the production are being automated to get

multifarious benefits. It has, therefore become imperative for the firms to get themselves equipped with

automation systems to meet the growing demand of goods. With the advent of globalization an

liberalization, it is necessary that industries explore methods of enhancing automation and thereby increase

the productivity to acquire greater competitiveness in the market. The existing automation systems are to be

redesigned to get preciseness and accuracy in their operations. The preciseness and accuracy of th

automation system are achieved through its controller. A better controller always enhances the quality in its

operations. Thus, there is an everlasting demand to have a better controller in the existing automation systems.

This project apart from optimizing an existing automation system also explicates the importance of one such

better controller i.e. Programmable Logic Controller (PLC).

project details: This project work is an explicative document on the concept of Low Cost Automation (LCA),

with an emphasized study on a Programmable Logic controller (PLC) and its programming techniques. The

project work also includes various elements of Sensors, since the Programmable Logic Controllers are used in

the control of sensors and cylinders.

The LCA techniques are considered to be one of the most commendable ones in solving various problems

related to automation. By its definition, low cost automation refers to the technology that creates some degreeof automation around the existing equipment, tools and methods, using mostly the standard equipment

available in the market.

The features of LCA are:

1. The automation of small to medium scale industries can be made viable.

2. Since it is built using the existing resources in a systematic way, the investment risks are low.

3. Labour productivity can be enhanced substantially.

It should be noted that the automation system employed as a modification to the existing system besides being

capable of solving the above problems, must be least affecting the economics of the firm. The concept of Low

Cost Automation (LCA) is considered as the best technique to solve such kinds of problems in automation.


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Generally, the solutions achieved through LCA techniques are optimal in all aspects. This project work

explicates one such solution to the problemfaced in load test on dc series generator. The problem dealt in this

project is controlling speed and loading dc series generator automatically. To overcome the problem of manual

controlling, it is better to go in for automation. This is achieved by using PLCs. The above automation problem

is one ofthose typical industrial problems, wherein a partial sequence of operations repeats itself. Automation

of these operations can be effectively carried out using low-cost automation techniques, which employ sensors

and PLCs to serve the purpose. Because of the fact that the task is being a repetitive one and the amount of

operation being limited, a conveyer and a group of sensors can be used to serve the purpose. It may be noted

that, the sensors used must operate in coordination with the existing automation system. The sensors used in

this project are also referred as sensors.

II. CONTROL TASK

definition control strategy: In order to design a solution to a problem related to automation it is imperative for

an Engineer to begin it by defining the control task, that is, determine what needs to be done. This information

provides the foundation for the control program. To minimize errors, the control task should be defined by

those who are familiar with the operation of the machine or the process. Proper definition of the task is

directly related to the success of the control program.

Control task definition occurs at many levels. All the departments involved, must work together to determine

what inputs are required so that every one understands the purpose and scope of the project. All the personnel

in the department must collaborate with the engineering group during the system definition.If the control task is done manually or through relay logic, we must review the steps of manual procedure to

determine what improvements, if any, can be made. Although relay logic can be directly implemented in a

PLC, the procedure should be redesigned, when possible, to meet the current project needs and to capitalize

on the capabilities of programmable controllers.

In the current project the control task is to perform load test on dc series generator, by signaling to their

respective drives and sensors, according to a sequence of operation. After the control task has been defined,

the planning of its solution can begin. This procedure commonly involves determining a control strategy,the

sequence ofsteps that must occur within the program to produce the desired output control. That is, to have a

complete idea of the trace of the program developed. This part of the program development is known as

development of an algorithm.

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The PLC strategy implementation for a control task closely follows the development of an algorithm. The

designer must implement the control from a set of basic instructions and produce the solution in a finite

number of steps. If development of algorithm to solve the problem becomes difficult, he must return to the

control task definition to redefine the problem. We cannot develop a control strategy until we have our

problem definition thoroughly defined.

Table 1: Aplications and Modernizations

III. MAIN COMPONENTS

Sensors: A sensor is a device that measures a physical quantity and converts it into a signal which can be read

by an observer or by an instrument. All the sensors have 16 pins in which 1 and 3 are given to ac supply line

and neutral respectively.7 and 8 are input pins, 9 and 10 are output pins which are given to PLC.

voltage sensor: Electrical voltage sensors measure AC and/or DC voltage levels. They receive voltage inputs

and provide outputs as analog voltage signals. We have used a voltage sensor by manufactured by pyramid

semiconductor corporation (SCM 8018).To this sensor input voltage of 0-300V is given from the load and this

voltage in converted in 0-10V which is in turn given to a PLC. Accuracy represents the difference between a

voltage measurement and the actual level.

Optional features for electrical voltage sensors include analog or digital visual indicators.

Some electrical voltage sensors are capable of measuring three-phase AC voltage..

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Fig 1: Voltage sensor

current sensor:A current sensor is a device that detects electrical current (AC or DC) in a wire, and

generates a signal proportional to it. We used SCM 8020 current sensor with a shunt which takes 0-20A

current and converts it to 0-10V DC which in turn is given to plc.

Fig 2: Internal circuit of current sensor

The sensed current and the output signal can be:

AC current input, analog output, which duplicates the wave shape of the sensed current unipolar output,

which is proportional to the average or RMS value of the sensed current DC current input, unipolar, with a

unipolar output, which duplicates the wave shape of the sensed current

bipolar output, which duplicates the wave shape of the sensed current digital output, which sw

when the sensed current exceeds a certain threshold

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Fig 3: Current sensor

1:1 sensor: Variable voltage from Dc drive is given as in put to the sensor and the same value of voltage is

reflected at the output. Since the ratio of input and output are same it is called as 1:1 sensor. We used

SCM8003 sensor it takes 0-10v from dc drive and gives it to PLC.

Fig 4: 1:1 sensor

proximity sensor:Proximity sensors are those sensors, which detect whether or not an object is located at a

certain position. Proximity sensors are so known as binary sensors and initiators.

Proximity sensors operate electronically and without contact.

fig 5: proximity sensorrelay:A relay is an electrical switch that opens and closes under the control of another electrical circuit. In

the original form, the switch is operated by an electromagnet to open or close one or many sets of contacts

When an electric current is passed through the coil, the resulting magnetic field attracts the armature, and

the consequent movement of the movable contact or contacts either makes or breaks a connection with a

fixed contact. If the set of contacts was closed when the relay was de-energized, then the movement opens

the contacts and breaks the connection, and vice versa if the contacts were open. When the current to the

coil is switched off, the armature is returned by a force, approximately half as strong as the magnetic force,

to its relaxed position. Usually this force is provided by a spring, but gravity is also used commonly in

industrial motor starters

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Fig 6: Relay

contactor: A contactor is an electro-magnetic switching device (a relay) used for remotely switching a

power or control circuit. A contactor is activated by a control input which is a lower voltage / current than

that which the contactor is switching. Contactors come in many forms with varying capacities and features.

Unlike a circuit breaker a contactor is not intended to interrupt a short circuit current. Contactors range from

having a breaking current of several amps and 110 volts to thousands of amps and many kilovolts.

Fig 7: Contactor

dc drives: DC motor drives act as an interface between a controller and the motor. The drive must match the

control signals (voltage and power levels) and signal type (analog or digital). The drive produces power

conversion, amplification, and sequencing of waveform signals. Types of DC motor drives include adjustabl

or variable speed control, servo control, and integral motion control. Some drives are capable of deliverin

adjustable or variable speed control

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http://upload.wikimedia.org/wikipedia/commons/a/aa/ACcontactor.JPG


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Fig 8: DC Drive

programmable logic controllers: PLC is defined as a digital electronic device that uses programmable

memory to store instruction and to implement function such as logic, sequencing, timing, counting, and

arithmetic in order to control machines and process. This is replacement for hard wired relay and timer logic

control system, the advantage of PLC is that control system can be modified without rewiring the

connections in the input output and is achieved by changing program instructions.

PLC is similar to computer but have certain features.

They are rugged in design to withstand vibration, temperature, humidity and noise.

Interfacing for inputs and outputs are inside the controller.

They can be easily programmed in an easily understood language.

Fig 9 Major functional parts of plc

software:Software is the means by which the plc is controlled.

It determines the action to be taken in response to given set of conditions. the creation of this software

is called programming or coding .

The manufactures supply standard set of commands called programming language, used to program

the plc.

introduction to codesys: CoDeSys is a complete development environment for our PLC. (CoDeSys stands for

Controlled Development System). CoDeSys puts a simple approach to the powerful IEC language at t

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disposal of the PLC programmer. Use of the editors and debugging functions is based upon the prove

development program environments of advanced programming languages (such as Visual C++).

setup of our project: First we configured our PLC in order to check the accuracy of the addresses used in our

project. Then we created the POUs needed to solve our problem. Now we programmed the POUs we needed in

the desired languages. Once our programming is completed, we compiled the project and removed errors.

testing our project: Once all errors have been removed, activated the simulation, logged in to the simulated

PLC and "load" your project in the PLC. Now we are in online mode. Now opened the window with our PLC

Configuration and tested our project for correct sequence. To do this, we entered input variables manually and

observed whether outputs are as expected. We also observed the value sequence of the local variables in the

POUs.

Debugging: In case of a programming error we set breakpoints. When the process stopped at such a breakpoint,

we examined the values of all project variables at that point in time. By working through sequentially (single

step) we checked the logical correctness of our program.

IV. THE RESOURCES

overview of the resources:In the Resources register card of the Object Organizer, there are objects

configuring and organizing our project and for keeping track of the values of the variables:

Global Variables that can be utilized in the entire project; the global variables of the project as well as the

libraries.

Alarm configuration for the organization of an alarm system in the CoDeSys project.Library Manager for handling all libraries which are included to the project.

Log for recording the activities during the online sessions.

PLC Configuration for configuring our hardware.

Watch and Receipt Manager for indicating and presetting variable values.

Task Configuration for controlling our program control via tasks.

Target settings for selecting the hardware platform (target) and if available for customizing target specific

parameters.

Workspace as an image of the project options.

Depending on the target settings the following resources also might be available:

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Parameter Manager for managing variables, which are also accessible for other participants in the network.

This functionality will only be available if defined in the corresponding target settings.

PLC Browser for monitoring of information from the PLC.

Sampling Trace for graphic logging of variable values.

Toolsfor linking external tools, which then can be started in CoDeSys. This functionality will only be

available if defined in the corresponding target settings.

The SoftMotion functionality (license needed): CNC program list(CNC Editor) and CAMs (CAMEditor)

Additionally there might be created and loaded a Docuframefile which offers a set of comments for the

project variables (e.g. in a certain language), which will be printed when documenting the project with

'Project' 'Document'.

Fig 10: Resources of PLC

plc configuration:The PLC Configuration was found as an object in the register card Resources in the

Object Organizer. With the PLC Configuration editor, we described the hardware the opened project is

established for. For the program implementation, the number and position of the inputs and outputs is

especially important. With this description, CoDeSys verifies whether the IEC addresses used in

program also actually exist in the hardware. The base of working in the configuration editor are the

configuration files (*.cfg; see below Note concerning version compatibility') and the device files (.e.g.

*.gsd, *.eds). These are stored in the directory which is defined in the target file (see Target Settings) and

are read when the project was opened in CoDeSys. We added files to these directories at that time.

The CoDeSys configuration editor allows us to configure I/O modules as well as CAN and Profibmodules. If supported by the target system, there is the possibility to get information from the PLC: 1. a

scan of the actual hardware structure which can directly be used in the PLC Configuration, 2. Diagnosis

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messages which will be displayed as messages in CoDeSys, 3. status information which will be displayed in

the PLC Configuration dialog.

Fig 11: Configuration Dialog Box

V. HARDWARE

The higher the number of I/O modules, the more sophisticated and more expensive the system. Several

CPUs are available, with varying speed, memory, and capabilities. Some systems provide redundant CPU

operation for ultra-high-reliability control, as used in pharmaceutical manufacturing, for example. Each

PLC consists of a power supply, and backplane with slots for addition of various option boards. Available

options include serial and Ethernet communication, digital input and output cards, analog signal processing

boards, counter cards, and other specialized interface and function modules

A. DC GENERATOR

An electrical Generator is a machine which converts mechanical energy (or power) into electrical energy (or

power).

Principle: It is based on the principle of production of dynamically (or motiona

(Electromotive Force). Whenever a conductor cuts magnetic flux, dynamically induced e.m.f. is produced in it

according to Faraday's Laws of Electromagnetic Induction. This e.m.f. causes a current to flow if the

conductor circuit is closed. Hence, the basic essential parts of an electric generator are:

A magnetic field and

A conductor or conductors which can so move as to cut the flux.

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B. CONSTRUCTION:

A single-turn rectangular copper coil abcd moving about its own axis in a magnetic field provided by either

permanent magnets or electromagnets. The two ends of the coil are joined to two split-rings which are

insulated from each other and from the central shaft. Two collecting brushes (of carbon or copper) press

against the slip rings

C. TYPES OF DC GENERATORS

DC generators are classified as shunt, series or compound-wound. Most dc is compound-wound type.

series generator: When the field winding of a DC generator is connected in series with the armature, the

generator is called a series-wound generator. The excitation current in a series-wound generator is the same

as the current the generator delivers to the load. If the load has a high resistance and only draws a small

amount of current, the excitation current is also small. Therefore, the magnetic field of the series field

winding is weak, making the generated voltage low. Conversely, if the load draws a large current, the

excitation current is also high. Therefore, the magnetic field of the series field winding is very strong, and

the generated voltage is high.

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Fig 12: Series-Wound DC Generator

In a series generator, changes in load current drastically affect the generator output voltage. A series

generator has poor voltage regulation, and, as a result, series generators are not used for fluctuating loads.

As is the case for the shunt-wound generator, a series-wound generator also exhibits some losses due to the

resistance of the windings and armature reaction. These losses cause a lower terminal voltage than that for

an ideal magnetization curve.

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Fig 13: Output Voltage-vs.-Load Current for Series-Wound DC

Series-wound and shunt-wound generators have a disadvantage in that changes in load current cause changes

in generator output voltage. Many applications in which generators are used require a more stable output

voltage than can be supplied by a series-wound or shunt wound generator. One means of supplying a stable

output voltage is by using a compound generator.

VI. AUTOMATION OF LOAD TEST ON SERIES GENERATOR

ratings:

MOTOR

Power= 5.0hp

Speed =1200rpm

Armature voltage=220V

Armature current=19.0 amps Armature c

Field voltage=220volts

Field current=1.0 amps

Wound= shunt

A. HARDWARE CONNECTIONS

Hard ware connections are done to several components.

The connections here have been done between 4 different panels. And these panels are:

Machine or the main circuit panel.

Drive and sensor panel.

Load panel.

PLC panel.

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These 4 panels are connected with each other and are driven by the software program in the PC. Let us first

consider each panel in detail.

machine panel: Here all the connections of load test on the series generator are done.

Fig 14: Machine Panel

drive panel: In this panel we arranged a DC drive, 4 sensors, a contactor and a MCB. MCB used here is a

single phase MCB so line supply was given to it. And the main (3-phase) supply was given to the contactor.

This contactors output terminals (R, Y and B) were then given to the DC drive and the neutral of the drive

was given from the A2 terminal of the contactor. And the A1 terminal of the contactor was given to the stop

button of the machine.

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Fig 15: Drive panel

load panel:

Fig 16: Load Panel

In this panel we arranged all the required loads for our project. We have used 14 bulbs as loads each having

a rating of 200W so, the total load becomes 2.8KW.

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plc panel: in this panel a PLC, contactors, relays, MCB, and SMPS were arranged. Whole PLC module has

been presented in this panel. The PLC had 9 modules, in which we have used 4 modules. 2 nd module was used

for loads and high speed counter, 3rd module for the stop button from the relays, 6th module for the output

terminals of the voltage and current sensors. Lastly, 9th module was used for the output terminals of the 1:1

sensor. Totally 5 contactors were used and the terminal A1 of each contactor was grounded.

Fig 17: PLC panel

Automation of DC series generator using PLC is advanced technology which reduces the manual work and

increases the accuracy. If this new wealth is allowed to trickle down through all societies, it could prove to

be of great economic

VII. RESULTS

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Automation of DC series generator using PLC is advanced technology which reduces the manual work and

increases the accuracy. If this new wealth is allowed to trickle down through all societies, it could prove to be

of great economic and social benefit. In this project we obtained characteristics automatically. Programmable

logic controllers provide entire control of the production as per the requirement.

Fig 18: Excel Sheet Showing Graph

REFERENCES

[1] B.L. Theraja and A.K. Theraja: A Textbook Of Electrical

Technology , Volume II AC & DC Machines in S.I.

System of Units, S.Chand & Company Ltd,1959.

[2] John Bird : Electrical Circuit Theory And Technology

[3] I.J Nagrath and D.P Kothari: Electric Machines , Tata mc

graw -hill publishers, 3rd edition, 2004

[4] www.datacatlog.com

[5 ]www.alldatasheets.com

[6] www.wikipedia.com

[7] User Manual for PLC Programming with CoDeSys 2.3

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