Design And Construction Of Temperature Control Automatic Switch

ABSTRACT

This project is titled design and construction of a temperature control automatic switch. It is designed to control electric appliances such as electric kettle, oven, incubator, or lamp through the variation of temperature range (0°C -100°C) which must be set by the user or operator. And this can be achieved by the use of temperature sensor known as THERMISTOR. This thermistor is a temperature control device with a high or low resistance value which can go high or low when the temperature is increased or reduced depending on the type.

In this project, 100C is used as a set temperature. And this device is design in such a way that when the set temperature of the device is reached, the relay of the device will automatically triggered and will maintain this stage until when the temperature of the sensor is dropped 97°C, and then it will return normally open stage in order to maintain that 100°C. And this automatic feature is controlled by a high current relay, and the two LED used are for power and temperature indication.

TABLE OF CONTENT

Title Page

Approval Page

Dedication

Acknowledgement

Abstract

Table of Content

CHAPTER ONE

1.0      Introduction

1.1      objective of the project

1.2      significance of the project

1.3      application of the project

1.4      scope of the project

1.5      limitation of the project

1.6      methodology

1.7      project organisation

CHAPTER TWO

2.0      LITERATURE REVIEW

2.1      Overview of temperature controller

2.2      Review of different types of temperature controller and their working principle

2.3      Major Component’s Description

2.1      Resistors

2.2      Diodes

2.3      Capacitors

2.4      Transformers

2.5      Transistor

2.6      Integrated Circuit

2.7     Thermistor

CHAPTER THREE

3.0      Sectional Description of the System

3.1      Comparator Section

3.2      Switching (relay) Section

3.3      Power supply

3.4     sensor

3.5   circuit operation

CHAPTER FOUR

4.0      Construction Procedure and Testing

4.1      Casing and Packaging

4.2      Assembling of Sections

4.3      Testing of System Operation

4.4      Installation of the Completed System

4.5      Problem Encountered

4.6      Cost Analysis

CHAPTER FIVE

5.1      Conclusion

5.2      Recommendation

5.3      Bibliography

CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                                         BACKGROUND OF THE PROJECT

A temperature controlled automatic switch controls appliances such as household electric kettle, which is usually has a heating element which is mounted at the bottom of a water tank through a heat conducting base. A conventional temperature control system typically uses a bi-metal temperature sensor (also known as a thermostat) to sense the temperature of the device, if it is used in electric kettle: the temperature of the water inside the kettle is measured and the steam when the water is boiled, and then cut off the electric power if the water temperature reaches the bi-metal action temperature point or if sufficient amount of steam is detected. Some modern temperature control switch uses more precise electronic temperature sensors such as the NTC (Negative Temperature Coefficient) resistors (thermistors), which are capable of sensing the temperature through a very wide range of points instead of just one point. In some cases, the control systems of the system is configured to take into account the temperature rising rate in addition to the absolute temperature value so that the control precision is greatly improved.

The idea behind the design and construction of this switch is to make available or alternative means providing safety and accuracy demand for switching household or industrial electrical appliances. This goes a long way in helping to curb the problem frequently encountered as a result of fire outbreak, burning of food, and inaccuracy found in measuring and maintaining temperature. That notwithstanding it makes it possible to have other means of heating food without constant temperature monitoring until when the required temperature will be achieved thereby creating time for the operator to be engaged on other works while the system is in operation.

Moreover, there are higher rate of fire accident cause by switching of devices. So there is every need that other means of safety should be made available for constant running of our electric equipments and gadgets and also to provide comfort to man. Hence, with the help of a Thermistor, which has come to solve the problem of fire accident and inaccuracy found in temperature measurement in Nigeria, a steady running and operation of our electric equipments and gadgets is guaranteed.

1.2                               OBJECTIVE OF THE STUDY

The objective of this work is to design a device which will automatically control or switch ON and OFF electrical appliances by sensing the temperature of the environment or the device which it is controlling without the help of the user.

1.3                                         SIGNIFICANCE OF THE PROJECT

Temperature controlled switch typically uses a temperature sensor (also known as a thermistor) to sense the temperature and then cut off the electric power if the temperature reaches the action temperature point. The temperature sensors, NTC (Negative Temperature Coefficient) resistors (thermistor), which is capable of sensing the water temperature through a very wide range of points.

1.4                                          APPLICATION OF THE PROJECT

Outside the culinary world, temperature control switch is used for a number of purposes.

Furnace: A furnace can be used either to provide heat to a building or used to melt substances such as glass or metal for further processing. A blast furnace is a particular type of furnace generally associated with metal smelting (particularly steel manufacture) using refined coke or similar hot-burning substance as a fuel, with air pumped in under pressure to increase the temperature of the fire.

kiln: A kiln is a high-temperature temperature control electric kettles used in manufacturing to convert mineral feedstock (in the form of clay or calcium or aluminum rocks) into a glassier, more solid form. In the case of ceramic kilns, a shaped clay object is the final result, while cement kilns produce a substance called clinker that is crushed to make the final cement product.

Autoclave: An autoclave is an kettle-like device with features similar to a pressure cooker that allows the heating of aqueous solutions to higher temperatures than water’s boiling point in order to sterilize the contents of the autoclave.

Industrial electric kettle: Industrial temperature control electric kettles are similar to their culinary equivalents and are used for a number of different applications that do not require the high temperatures of a kiln or furnace.

1.5                                                 SCOPE OF THE PROJECT

Temperature controlled switch include a relay, power supply and a sensor for sensing the temperature of the environment or device, and a control unit being configured to collect data during the operation of the circuits. The control unit is also configured to execute a predetermined program and calculate a cut-off temperature based on the data and a predetermined target temperature. The control unit is further configured to turn off the electric power provided to the controlled appliances through a relay, when the temperature of the sensor is equal to or greater than the calculated cut-off temperature.

1.7                                           LIMITATION OF THE PROJECT

Though temperature controlled switch is designed to controlled appliances, but when the sensor is directly exposed to liquid (water) can damaged the sensor thereby causing the system to malfunctioning.

1.8                                         METHODOLOGY

To achieve the aim and objectives of this work, the following are the steps involved:

1. Study of the previous work on the project so as to improve it efficiency.
2. Draw a block diagram.

• Test for continuity of components and devices,

1. Design of the device was carried out.
2. Studying of various component used in circuit.
3. Construction of the circuit was carried out. The construction of this project includes the placing of components on Vero boards, soldering and connection of components,

• Finally, the whole device was cased and final test was carried out.

1.9                                             PROJECT ORGANISATION

The work is organized as follows: chapter one discuses the introductory part of the work, chapter two presents the literature review of the study, chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.

CHAPTER TWO

2.0                                                    LITERATURE REVIEW

2.1                           OVERVIEW OF TEMPERATURE CONTROL

As the name implies, a temperature controller is an instrument used to control temperatures, mainly without extensive operator involvement. A controller in a temperature control system will accept a temperature sensor such as a thermocouple or RTD as input and compare the actual temperature to the desired control temperature, or setpoint. It will then provide an output to a control element.

A good example would be an application where the controller takes an input from a temperature