Design And Construction Of A Micro Controller Based Starter For Single Phase Induction Motor With Delay

ABSTRACT

It is well understood that induction motors draw higher currents during their starting operations than is the case under full load running conditions. Since the early days of induction motor availability, starting methods other than Direct-on-Line have been used, and in some cases mandated by Utilities, to reduce the effect of these high starting currents on the electrical distribution network. What is generally not recognized is the existence of short duration inrush currents, which greatly exceed these starting currents. Furthermore, the introduction of complex starting methods to reduce starting currents is often compromised by other unanticipated inrush currents introduced by the starting system itself, unless special precautions are taken. This paper implements a device that protects three phase induction motor from inrush currents on the distribution system, as well as on the motor protection components using PIC16F84A Microcontroller.

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• PROBLEM STATEMENT
• AIM AND OBJECTIVES OF THE PROJECT
• SCOPE OF THE PROJECT
• MOTIVATION OF THE STUDY
• SIGNIFICANCE OF THE PROJECT
• LIMITATION OF THE PROJECT

CHAPTER TWO

LITERATURE REVIEW

• OVERVIEW OF INDUCTION MOTOR
• BASIC PARTS OF AN INDUCTION MOTOR
• OVERVIEW OF SINGLE PHASE MOTOR
• APPLICATIONS OF SINGLE PHASE INDUCTION MOTOR
• ADVANTAGES OF INDUCTION MOTOR
• REVIEW OF STARTING METHODS OF SINGLE PHASE MOTOR
• BASICS OF INDUCTION MOTOR
• REVIEW OF RELATED STUDIES

CHAPTER THREE

3.0      METHOD

CHAPTER FOUR

4.1      RESULTS AND DISCUSSION

CHAPTER FIVE

• CONCLUSION
• REFERENCES

CHAPTER ONE

1.0                                                     INTRODUCTION

1.1                                       BACKGROUND OF THE STUDY

Induction motors are popular due to their low-cost, sturdy construction, fast pick-up, low maintenance expenditure and good efficiency. The DOL (direct-on-line) starters and star/delta starters used for starting and running of induction motors provide coarse type of protections against voltage fluctuations and single phasing. Induction motors are very sensitive to low voltage and single phasing during which they draw a heavy current and can burn out unless switched of within few seconds of occurrence of such conditions. This makes the requirement of a sensitive protective device essential to avoid burning of induction motors under such conditions. The circuit of an automatic starter, incorporating the important features given below, is described here. It is meant to be used in conjunction with a DOL starter. Automatic start on resumption of proper conditions Single phasing prevention 24-hour programmable off timer (on completion of actual runtime of the motor). An induction or asynchronous motor is a type of AC motor where power is supplied to the rotor by means of electromagnetic induction, rather than a commutator or slip rings as in other types of motor. These motors are widely used in industrial drives, particularly poly-phase induction motors, because they are rugged and have no brushes. Single-phase versions are used in small appliances. Their speed is determined by the frequency of the supply current, so they are most widely used in constant-speed applications, although variable speed versions, using variable frequency drives are becoming more common. The most common type is the squirrel cage motor.

1.2                                                            PROBLEM STATEMENT

Starting a motor using traditional methods involve running the motor at full speed and then using mechanical means such as gears, hydraulic couplings or pulleys. This is not only expensive, but also consumes a lot of energy. There are many means of controlling induction motor speed, but the most popular problem discovered in them is that motor used to experience speed instability and the efficiency of the motor drops when the motor speed is varied. Using microcontroller for motor speed control came to solve this problem. By varying the voltage and frequency, but keeping their ratio constant, the torque developed can be kept constant throughout the speed range thereby maintaining the motor efficiency.

1.3                                             AIM AND OBJECTIVE OF THE PROJECT

AIM

The main aim of this project is to build a starting device for an induction motor using microcontroller.

OBJECTIVE

The objectives are:

1. To enhance the efficiency of motor control techniques by using PIC microcontroller for a three phase induction motor speed control.
2. To show the performance of an induction motor using microcontroller.

• To build an induction motor starting device.

1.4                                                             SCOPE OF THE STUDY

Starting of an electrical drive involves a change in its state from rest to a steady state speed of rotation. The process of starting is the most important phenomenon in the entire operation of the drive. Control of the starting process essentially consists of controlling the acceleration of the driving motor and the latter is basically a problem of modifying the speed torque characteristics of the motor in such a way as to obtain the desired starting performance. This work involve building a PIC microcontroller based induction motor starter..

1.5                                                      SIGNIFICANCE OF THE STUDY

This research work will throw more light on the best techniques for controlling the speed of electric motor. This study will also be designed to be of immense benefit to all the users of electric motor most especially in industries.

It will also serve as a guide to whoever that wants to purchase speed controller for induction motor.

Finally, it will also serve as a useful piece of information for both producers and users of electric motor speed controller.

1.6                                                      MOTIVATION OF THE STUDY

Starting an induction motor is very necessary to consider for both industrial and local applications in that it determines how safe the motor will operate and the energy savings. The advantages of using this method of motor speed control is because it is cheap and efficient means of starting an induction motor. However, advantages discussed above were points that motivate the carrying out of this research work.

1.8                                                        LIMITATION OF THE STUDY

As we all know that no human effort to achieve a set of goals goes without difficulties, certain constraints were encountered in the course of carrying out this project and they are as follows:-

1. Difficulty in information collection: I found it too difficult in laying hands of useful information regarding this work and this course me to visit different libraries and internet for solution.
2. Difficulty in parts gathering: I found it too difficult when gathering electronics parts used for the prototype and also difficulty in getting the system simulated.