Key Features:
Pages: 46
Chapters: Six
Format: Ms word
Delivery Rate: Fast
Abstract:
A direct on line starter, often abbreviated DOL starter is an electrical/electronic circuit composed of electro-mechanical and electronic devices which are employed to start and stop an electric motor. Regardless of the motor type (AC or DC), the types of starters differ depending on the method of starting the motor. A DOL starter connects the motor terminals directly to the power supply. Hence, the motor is subjected to the full voltage of the power supply. Consequently, high starting current flows through the motor.
Electric motors can run in both forward and reverse direction depending on the requirement of the application where it is to be installed, for example, like in a conveyor system which would require moving on both direction of items contained in the conveyor table. When such arrangement is necessary for a certain type of application, then a forward reverse motor controller is applied to the control circuit of the electric motor to achieve this purpose. Again the device required for the possibility of this operation is the magnetic contactor.
This work is on operating forward and reverse of a direct online starter using contactor.
Table of Content:
Title page i
Certification ii
Dedication iii
Acknowledgement iv
Abstract v
List of figures vi
List of tables vii
Table of contents viii
CHAPTER ONE
1.0 Introduction 1
1.1 Background of the Study 1
1.2 Statement of the Problem 2
1.3 Research Objectives 2
1.4 Contribution to Knowledge 2
1.5 Limitation/ Scope of Study 2
1.6 Methodology 3
1.7 Definition of Terms 4
CHAPTER TWO
2.0 Literature review 5
2.1 Brief outline of the chapter 5
2.2 Historical background of study 6
2.3 Theory and concept related to the research 12
CHAPTER THREE
3.0 Research Methodology 13
3.1 Brief outline of the chapter 13
3.2 Research design 13
3.3 Block by block unit of design 22
CHAPTER FOUR
4.0 Principle of operation of the project 23
4.1 Brief introduction of the chapter 23
4.2 Principle of operation 24
4.3 Explanation of various unit 29
CHAPTER FIVE
5.0 Construction of a Direct Online Starter 30
5.1 A brief outline of the project 30
5.2 Choice of material 31
5.3 Construction of a Direct Online Starter 33
5.4 BEME table 34
5.5 Test(s) result of test 35
CHAPTER SIX
6.0 Conclusion, summary and recommendation 36
6.1 Summary of the project chapter by chapter 36
6.2 Problems encountered 37
6.3 Recommendation 38
6.4 Conclusion 38
REFERENCES 39
Introduction:
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF THE STUDY
A motor controller is a device or group of devices that serves to govern in some predetermined manner the performance of an electric motor. A motor controller might include a manual or automatic means for starting and stopping the motor, selecting forward or reverse rotation, selecting and regulating the speed, regulating or limiting the torque, and protecting against overloads and faults.
A small motor can be started by simply plugging it into an electrical receptacle or by using a switch or circuit breaker. A larger motor requires a specialized switching unit called a motor starter or motor contactor. When energized, a direct on line (DOL) starter immediately connects the motor terminals directly to the power supply. Reduced-voltage, star-delta or soft starters connect the motor to the power supply through a voltage reduction device and increases the applied voltage gradually or in steps. In smaller sizes a motor starter is a manually operated switch; larger motors, or those requiring remote or automatic control, use magnetic contactors. Very large motors running on medium voltage power supplies (thousands of volts) may use power circuit breakers as switching elements.
1.2 STATEMENT OF THE PROBLEM
i. It will put high thermal stress on the motor and that will reduce the motor life.
ii. High starting current will leads to dips in voltage.
iii. The unnecessary high starting torque required by the load may cause increasing mechanical stress on motor mechanical parts as well as the load.
1.3 RESEARCH OBJECTIVE
i. To construct an electrical device that can be used to start and control the direction of AC motor.
ii. To test the constructed starter.
1.4 CONTRIBUTION TO KNOWLEDGE
i. This project helps us to understand the working principle of a direct online starter.
ii. It helps us to understand how each components works.
1.5 LIMITATION OF THE PROJECT
This motor starter is simply manual switches designed to control larger current loads typical of motor control. They may be small and similar to the light switches in your home, or they may be much larger dedicated switches designed for control of high amperage circuits. This motor starter is Triple Pole devices (switch 2/3 lines). This device was built using Normally Closed (STOP) and Normally Open (START) momentary contact switches and normally close (reversing) switch.
1.6 METHODOLOGY
This project contains detailed analysis of the working and the construction of a Direct Online Starter, and also the books that were consulted and the site that was visited to get materials for the successful completion of this project report (Direct Online Starter).
1.7 DEFINITION OF TERMS
Overload relay: This is an electromechanical protection device for the main circuit.it offer reliable protection for motors in the event of overload or phase failure.it can make up a compact starting solution together with the contactors.
Contactor: A contactor is an electrically-controlled switch used for switching an electrical power circuit. A contactor is typically controlled by a circuit which has a much power level than the switched circuit, such as a 20-volt coil electromagnet controlling a 230-volt motor switch.
Miniature circuit breaker: A miniature circuit breaker [MCB] automatically switches off electrical circuit during an abnormal condition of the network means in overload condition as well as faulty condition. Nowadays we use MCB in low voltage electrical network instead of a fuse.
Direct online starter: A direct online starter is the simplest kind of starter that connect the motor directly to the power supply through a three phase contactor.
Buy Now
