Role Of Buchholz Relay In Transformer And Construction

ABSTRACT

In common practice, there are so many protection systems being used for the protection of power transformers from abnormal conditions. Power transformer which carries a huge amount of power from one location to another needs to be protected against faults. One special protective device Buchholz relay provides protection against different slow developing faults.  Buchholz relay is used for the protection of transformers from the faults occurring inside the transformer. Short circuit faults such as inter turn faults, incipient winding faults, and core faults may occur due to the impulse breakdown of the insulating oil or simply the transformer oil.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

CHAPTER ONE

INTRODUCTION

• AIM OF THE STUDY
• OBJECTIVE OF THE PROJECT
• PURPOSE OF THE STUDY
• DEFINITION OF BUCHHOLZ RELAY
• ADVANTAGES OF BUCHHOLZ RELAY
• LIMITATION OF BUCHHOLZ RELAY
• APPLICATIONS OF BUCHHOLZ RELAY

CHAPTER TWO

LITERATURE REVIEW

• REVIEW OF THE STUDY
• GENERAL FEATURES OF BUCHHOLZ RELAY
• OPERATING FEATURES

CHAPTER THREE

METHODOLOGY

• SETUP DIAGRAM
• WORKING PRINCIPLE OF THE RELAY
• CONSTRUCTION OF BUCHHOLZ RELAY
• OPERATION BUCHHOLZ RELAY
• OPERATE CONDITION OF BUCHHOLZ RELAY

CHAPTER FOUR

TESTING AND RESULTS

• CONSTRUCTION FEATURE, FINISH AND ACCESSORIES
• BUCHHOLZ RELAY CONTACTS
• ENVIRONMENTAL CONDITIONS
• INSTALLATION

CHAPTER FIVE

• CONCLUSION
• REFERENCES

 CHAPTER ONE

1.1                                                        INTRODUCTION

In the field of electric power distribution and transmission, a Buchholz relay is a safety device mounted on some oil-filled power transformers and reactors, equipped with an external overhead oil reservoir called a “conservator”. The Buchholz relay is used as a protective device sensitive to the effects of dielectric failure inside the equipment. A generic designation for this type of device is “gas detector relay”.

The Buchholz Relay was first implemented in the year 1921 by “Max Buchholz. This relay is a security device used in the fields like the transmission of power, as well as distribution. This relay had kept on some oil-filled transformers, and used as a protective device for die-electric failures in the transformer like current leakage, fractional discharge, hot spots and arcing are phenomena that deliver to oil degradation insulation acts by producing a hazardous flow of gas in the transformer tank. When the transformer was close, then it has a large economic impact on the power supply network operation. Thus, it is the aim to make sure an exact measurement of the transformer condition.

Buchholz relays have been applied on oil-filled power and distribution transformers at least since the 1940s. The relay is connected to the oil piping between the conservator and oil tank of a transformer. The piping between the main tank and conservator is arranged so that any gas evolved in the main tank tends to flow upward toward the conservator and gas detector relay.

1.2                                                   AIM OF THE PROJECT

Buchholz Relay being a security device used in the fields like the transmission of power, as well as distribution, the aim of this work is to highlight the role this relay play in transformer.

1.3                                             OBJECTIVE OF THE PROJECT

At the end of this work, student involved shall know:

1. The definition of bucholz relay
2. Its applications
3. Roles it play in transformer
4. And other application of the relay

1.4                                              PURPOSE OF THE PROJECT

The Buchholz relay purpose is to give the protection to a transformer from the different faults happening in the transformer like the Short circuit, inter-turn, core, incipient, etc. This relay will sense these faults and shuts the alarm circuit.

1.5                                       DEFINITION OF BUCHHOLZ RELAY

Buchholz relay is a type of oil and gas actuated protection relay universally used on all oil immersed transformers having rating more than 500 kVA. Buchholz relay is not provided in relays having rating below 500 kVA from the point of view of economic considerations.

1.6                              ADVANTAGES OF BUCHHOLZ RELAY

• Buchholz relay indicates inter turn faults and faults due to heating of core and helps in the avoidance of severe faults.
• Nature and severity of fault can be determined without dismantling the transformer by testing the air samples.

1.7                                       LIMITATION OF BUCHHOLZ RELAY

It can sense the faults occurring below the oil level only. The relay is slow and has a minimum operating range of 0.1second and an average operating range of 0.2 seconds.

1.8                                    APPLICATIONS OF BUCHHOLZ RELAY

The following types of transformer faults can be protected by the Buchholz relay and are indicated by alarm:

1. Local overheating
2. Entrance of air bubbles in oil
3. Core bolt insulation failure
4. Short circuited laminations
5. Loss of oil and reduction in oil level due to leakage
6. Bad and loose electrical contacts
7. Short circuit between phases
8. Winding short circuit
9. Bushing puncture
10. Winding earth fault.