Design And Construction Of Capacitor Leakage Tester

ABSTRACT

The ability of a capacitor to store electric charges is known as its capacitance, and that is what a capacitance meter is used for. A capacitance meter is used for measuring the capacitance of a capacitor. It measures the rate of charge storage and returns the value of capacitance in a digital fashion. A capacitance meter measures capacitance, mainly of discrete capacitors. Depending on the sophistication of the meter, it may display the capacitance only, or it may also measure a number of other parameters such as leakage, equivalent series resistance (ESR), and inductance.

This device has two output probes which can be easily connected to the two legs of the capacitor to measure its capacitance.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

• INTRODUCTION
• BACKGROUND OF THE PROJECT
• PROBLEM STATEMENT
• AIM AND OBJECTIVE OF THE PROJECT
• SIGNIFICANCE OF THE PROJECT
• APPLICATION OF THE PROJECT
• SCOPE OF THE PROJECT
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

• REVIEW OF CAPACITANCE
• REVIEW OF CAPACITORS
• THE CAPACITANCE OF A CAPACITOR
• REVIEW OF DIFFERENT METHOD OF CAPACITOR TESTING
• REVIEW OF RELATED WORKS

CHAPTER THREE

METHODOLOGY

• BLOCK DIAGRAM OF A CAPACITANCE METER
• CIRCUIT DIAGRAM
• CIRCUIT OPERATION
• DESCRIPTION OF COMPONENTS USED

CHAPTER FOUR

4.0      TEST AND RESULT ANALYSIS

• CONSTRUCTION PROCEDURE AND TESTING ANALYSIS
• CASING AND PACKAGING
• ASSEMBLING OF SECTIONS
• TESTING OF SYSTEM OPERATION
• THE NULL CIRCUIT
• HOW TO USE THE CAPACITANCE METER
• TROUBLESHOOTING METHOD

CHAPTER FIVE

• CONCLUSION
• RECOMMENDATION
• REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                                         BACKGROUND OF THE PROJECT

The capacitors are very common in basic components in any electronic device, it’s a passive two-terminal electronic component they can store energy in the electrical field and the capacity of the capacitor is a capacitance. The capacitor with a large capacitance will store more charge. There are different type of capacitance meters are available which allows you to measure the capacitance directly between 0.1 Pico farad and 20 microfarads. The unit of capacitance is farad represented by a letter ‘F’. There are several methods to measure the capacitance but the most accurate method is the bridge method. This work discusses the design and construction of the capacitance meter.

A capacitance meter is a piece of electronic test equipment used to measure capacitance, mainly of discrete capacitors. This meter is invented by Ewald Georg Von Kleist (10 June 1700) and Pieter Van Musschenbroek (16 March 1692) in 1975. The components used to design capacitance is called capacitors that can be used almost in all electronic devices to store electrical charge.

Depending on the sophistication of the meter, it may display the capacitance only, or it may also measure a number of other parameters such as leakage, equivalent series resistance (ESR), and inductance. For most purposes and in most cases the capacitor must be disconnected from circuit; ESR can usually be measured in circuit.

Some checks can be made without a specialized instrument, particularly on aluminium electrolytic capacitors which tend to be of high capacitance and to be subject to poor leakage. A multimeter in a resistance range can detect a short-circuited capacitor (very low resistance) or one with very high leakage (high resistance, but lower than it should be; an ideal capacitor has infinite DC resistance). A crude idea of the capacitance can be derived with an analog multimeter in a high resistance range by observing the needle when first connected; current will flow to charge the capacitor and the needle will “kick” from infinite indicated resistance to a relatively low value, and then drift up to infinity. The amplitude of the kick is an indication of capacitance. Interpreting results requires some experience, or comparison with a good capacitor, and depends upon the particular meter and range used.

More sophisticated instruments use other techniques such as inserting the capacitor-under-test into a bridge circuit. By varying the values of the other legs in the bridge (so as to bring the bridge into balance), the value of the unknown capacitor is determined. This method of indirect uses of measuring capacitance ensures greater precision. The bridge usually can also measure series resistance and inductance. Through the use of Kelvin connections and other careful design techniques, these instruments can usually measure capacitors over a range from picofarads to farads. Combined LCR meters that can measure inductance, resistance, and capacitance are available.

Bridge circuits do not themselves measure leakage current, but a DC bias voltage can be applied and the leakage measured directly.

Modern bridge instruments usually include a digital display and, where relevant, some sort of go/no go testing to allow simple automated use in a production environment. As with all modern instruments, bridges can be interfaced to computer and other equipment to export readings and allow external control.

1.3                                                  PROBLEM STATEMENT

There has always been a problem identifying capacitors, due to the enormous variety in size, shape and coding. Most of the time it is impossible to identify them by size due to the different forms of construction. So you have to be able to read and interpret the codes on the body. But if the numbers are missing or microscopic in size, you have a problem. The only solution is to have a piece of test equipment- capacitance meter, to identify them for you.

1.2                                             OBJECTIVE OF THE PROJECT

The objective of this project is construct an electronic testing equipment used to measure capacitance, mainly of discrete capacitors.

1.4                                                 SCOPE OF THE PROJECT

This project is capable of measuring all but the largest capacitors used in circuits. As well, the markings of capacitors from salvaged equipment often rub off. By being able to measure these unmarked components.

1.5                                              PURPOSE OF THE PROJECT

The purpose of this work is to design a piece of electronic test equipment used to measure capacitance, mainly of discrete capacitors. Depending on the sophistication of the meter, it displays the capacitance of capacitors only

1.6                                    APPLICATIONS OF THE PROJECT

• Capacitance Meter can be used to measure capacitance of unknown capacitors.
• Using 555 timer for Capacitance Meter makes it easy to implement the project and with slight modifications, the circuit can be made for a wide range of capacitors.

This project will prove useful to the constructor, vintage radio enthusiast or antenna experimenter.

1.7                                         SIGNIFICANCE OF THE PROJECT

The advantages of the capacitance meter are

• Hardware requirements are less
• Simple construction
• Small in size
• Less weight

1.8                          PROJECT WORK ORGANISATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this works is on the introduction to the study. In this chapter, the background, significance, objective, purpose, scope, application, limitation and problem of the study were discussed.

Chapter two is on literature review of this study. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.