Design And Construction Of A Password Based Circuit Breaker

1.0 INTRODUCTION
Nowadays, electrical accidents to the line man are increasing, while repairing the electrical lines due to the lack of communication between the electrical substation and maintenance staff. This project gives a solution to this problem to ensure line man safety. In this proposed system the control (ON/OFF) of the electrical lines lies with line man.
This project is arranged in such a way that maintenance staff or line man has to enter the password to ON/OFF the electrical line. Now if there is any fault in electrical line then line man will switch off the power supply to the line by entering password and comfortably repair the electrical line, and after coming to the substation line man switch on the supply to the particular line by entering the password.
The main component in the circuit is 8051 microcontroller. In this project 4×3 keypad is used to enter the password. The password which is entered is compared with the predefined password. If entered password is correct then the corresponding electrical line is turned ON or OFF. In this project a separate password is provided to each electrical line. Activation and deactivation of the line (circuit breaker) is indicated by the load.
The project is designed to control a circuit breaker with help of a password. This proposed system provides a solution, which can ensure the safety of the maintenance staff. EXAMPLE: Line man. The control to turn ON/OFF the line lies with the line man only
This system has an arrangement such that a password is required to operate the circuit breaker (ON/OFF). Line man can turn off the supply and comfortably repair it, and return to the substation, then turn on the line by entering the correct password. The system is fully controlled by a microcontroller IC. If the password entered is correct, then only the line can be turned ON/OFF. Activation / deactivation of the circuit breaker is indicated by a lamp (ON/OFF).

1.1 OBJECTIVE OF THE PROJECT
Circuit breaker is designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and interrupt current flow. It protects an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city. The main objective of this work is to design a device that can perform these functions using keypad instead of switch to control the ON or OFF of appliances

1.2 SIGNIFICANCE OF THE PROJECT
• Avoids electrical accidents to line man
• Project is simple and easy
• Uses commonly available components

1.3 APPLICATION OF THE PROJECT
• Used in electrical substations to ensure line man safety
• This system is used in buildings and houses
• Used in hotels and shopping malls to save the power.

1.4 SCOPE OF THE PROJECT
The above circuit consists of 8051 series controller, 4×3 keypad, LCD, relays and two loads. LCD data pins are connected to PORT1 and control pins RS, RW, EN pins are connected P3.7, P3.6 and P3.5 respectively. Here LCD is used to display the information. Keypad is connected to PORT2 of the controller. Using this keypad we need to enter the password. Lamps are connected to P3.0 and P3.1 through the relays. These are used to indicate circuit breaker state. In this project we have used bc547 transistors to drive the relays. AC load should be connected to COM and NO (Normally open) pins. 5V relays are used to drive the AC loads.

1.5 LIMITATION OF THE PROJECT
1. They are more expensive than fused switches
2. When a circuit breaker trips, you lose all power (with fuses you only lose that phase)
3. Harder to coordinate fault selectivity
4. Harder and more costly to obtain high short circuit interrupting capacities

1.6 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 work is on the introduction to a password circuit breaker. In this chapter, the background, significance, objective limitation and problem of a password circuit breaker were discussed.
Chapter two is on literature review of a password circuit breaker. 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.