The Design And Construction A 3-Phase Automatic Voltage Stabilizer

TABLE OF CONTENTS

TITLE PAGE

CERTIFICATION

DEDICATION

ACKNOWLEDGEMENT

TABLE OF CONTENTS

LIST OF TABLE

ABSTRACT

CHAPTER ONE

1.0      INTRODUCTION

• AIM AND OBJECTIVE OF THE PROJECT

1.3 TRANSFORMER CONFIGURATION

CHAPTER TWO

2.0      LITERATURE REVIEW

• HISTORY OF THE PROJECT
• THE POWER SUPPLY
• THEORY OF TRANSFORMER
• OPERATION OF THE TRANSFORMER
• VOLTAGE TRANSFORMATION RATION
• TRANSFORMER LOSSES

CHAPTER THREE

3.0      CONSTRUCTION OF THE SYSTEM

• SYSTEM CIRCUIT DIAGRAM
• CIRCUIT OPERATION
• MODE OF OPERATION
• CONTRUCTION PROCEDURE
• DESIGN FO THE TRANSFORMER PROPER
• SUMMARY OF THE SPECIFICATION OF TRANSISFORMER
• SHORT CIRCUIT TEST
• TESTING OF THE TRANSFORMER
• OPEN CIRCUIT TEST
• DESCRIPTION OF TRANSFORMER USED.

CHAPTER FOUR

4.0      RESULT ANALYSIS

• TESTING ANALYSIS
• SYSTEM POWER-UP
• INSTALLATION OF THE SYSTEM
• UNPACKING AND INSPECTION
• TROUBLESHOOTING METHOD OF THREE PHASE AUTOMATIC VOLTAGE REGULATOR.
• MAINTENANCE OF THE SYSTEM

CHAPTER FIVE

• SUMMARY
• CONCLUSION
• RECOMMENDATION
• REFERENCES

ABSTRACT

This project is titled the design and construction of a three phase Voltage Stabilizer. It is designed to meet up with the AC voltage safety, stability and accuracy demand in industries and in homes.

Three phase automatic Voltage stabilizers are useful in devices or load that have three phase such as computer Power supplies, alternators and central power station generator plants, voltage regulators control the output of the plant. In an electric power distribution system, three phase voltage regulators may be installed at a substation or along distribution lines so that all customers receive steady voltage independent of how much power is drawn from the line.

Three phase stabilizer is more versatile and is the most commonly used type for use with three phase loads. This basically consists of 3 single phase units of 1/3rd capacity each.  In this type, the output voltage on all three phases is equal even if the input voltage and the loads connected on the three phases are entirely different (unbalanced).

An AC Automatic voltage stabilizer is designed to automatically maintain a constant AC voltage level. An AC Voltage Stabilizer may be a simple “feed-forward” design or may include negative feedback control loops. It makes use an electromechanical mechanism, and other electronic components. It is used to regulate three different AC voltages.

The aim of this project is to design a three phase stabilizer which can stabilize an AC input voltage of 160-250V to give three output AC output voltages of 220V at 50Hz automatically. The automatic feature can be achieved by the electronics devices used such voltage comparator IC, electro-magnetic device (relay), three phase transformer and other electronics devices.

 CHAPTER ONE

1.0                                                   INTRODUCTION

There are many fundamental different types of stabilizers in use some of which are electron mechanically tap changer, solid state tap changer etc. voltage, stabilizer came into being not by normal design and plain, but as a means of solving electrical “Crisis” situation.  This crisis situation does rarely occur in developed countries of the world such as Britain, American, Germany etc, why?

Their system of generation, transmission and distribution of electricity is such that a devoid of variation of fluctuation in  the supplied voltage.  Now, by the definition given by K.G Jackson and R. Feinberg, a voltage stabilizer is a piece device incorporated in a circuit to maintain a constant output voltage from a poorly generated power supply.  A voltage stabilizer like any other piece of equipment is a combination of many electrical and like any other piece of equipment is a combination of many electrical and electronic and circuit with the aim of getting the assemble to perform a specified desired task or  the function.

Referring the  topic at hand, which is three phase automatic three phase voltage stabilizer which is the type of automatic voltage stabilizer with three phase output. This three phase AVR is fitted with isolation transformers in a delta-star configuration. This provides and clean, isolated supply to the load with a ‘new’ neutral connection. The AVR is made up from three identical single phase regulator units. Each of these monitors its own output voltage and adjusts for variations in mains supply voltage so as to maintain an output voltage within close limits.

When the AVS function is fitted, the outputs from the regulator are connected through a contactor to the load. The contactor is controlled by a three phase Automatic Voltage Switcher PCB which monitors the AVR outputs. This connects the load only when all the phase voltages are within acceptable limits. There is a delay function in the AVS to prevent frequent switching of the load.

A change-over switch is provided to by-pass the AVR in the event of needing to perform maintenance on the AVR.

An output circuit breaker is provided to protect the AVR from overload current and short circuit loads. Fans and thermal switches provide temperature control and protection. Filters, suppressors and fuse provide electrical protection.

1.2                 AIM AND OBJECTIVE OF THE PROJECT

Most electrical appliance this day highly sophisticated to the entreated that cases of intermitted or regular power outages, under voltages or over voltages are not tolerate in them.  The initial outlay and the cost or repair (in case of damage) are so economical that is means of maintain steady or regulated a.c power supply to these expensive appliance/equipment must sought for.

The cost of purchasing some already made imported voltage stabilizer is enormous.  Not readily available in our local markets while importing them requires high foreign exchange, the sown tunes is also much before, there is need to embark on this project work the design and construction automatic voltage stabilizer any form of voltage fluctuating (under voltage or over voltage) from the NEPA mains supply to domestic and industrial consumer premise.  It  is also one of the objectives of this project work that cost comparison between the imported or factory assembled voltage stabilizer e.g SORTEX OR BINATONE products and a locally fabricated voltage stabilizer be embarked on and that work be done on this project in order to finally produce a device that would perform optimally and also relatively cheaper.

1.2 TRANSFORMER CONFIGURATION

These AVRs are fitted with isolating transformers, one per phase. These provide a high degree of isolation from input to output. They also greatly attenuate common mode noise from the supply and prevent it reaching the load.

The primaries are each nominally 415V rated and are connected in a delta

configuration. Indoor 50A and outdoor 50A AVRs, the primaries are made up of two coils connected in parallel. The 12A and 20A transformers have single coils.

The secondary voltages are nominally 230V rated and are connected in a star configuration so as to generate a new neutral point. The secondary are in fact made of two coils each connected in parallel.

A further advantage of the delta input configuration is that an incoming neutral

connection is not required from the supply. Often neutral supply connection are poor or missing and this can cause damage to loads and regulators due to high phase to neutral voltages that result.