Nowadays, the current power system deals with huge power network as well as associated electrical equipment. During the electrical fault or short circuit, the power network will suffer from a high stress of fault current in them which may harm the equipment permanently. For conserving the power networks and equipment, the fault current should be very cleared from the system as fast as possible. To overcome this problem, the proposed system password based circuit breaker gives a solution to ensure lineman security. In this project, the control (ON/OFF) of the electrical lines lies with lineman. This project is set in such a way that preservation staff or lineman has to enter the password to ON/OFF the electrical line.
Now, if there is any mistake in the electrical line, then the lineman will control the power supply to the line by pressing the password and happily repair the electrical line, and after coming to the substation lineman switch on the supply to the particular line by pressing the password. Separate passwords are allocated for every electrical line.
What is Circuit Breaker?
An electrical circuit breaker is a switching device which can be functioned manually as well as routinely for protection and control of electrical power system. As the modern power system deals with huge currents, the special concentration should be given during designing of a circuit breaker to secure interruption of the arc generated during the working of the circuit breaker. This was the normal definition of the circuit breaker.
Password Based Circuit Breaker
The hardware and software requirements of password-based circuit breaker include Power supply block, Microcontroller (at89s52/at89c51), Pushbutton, LCD, Matrix keypad, Relay, Relay driver LED, 1N4007, Capacitors, and Resistors. Keil compiler, Embedded C or Assembly language.
The microcontroller is a smaller computer; it has on-chip RAM, ROM, I/O ports.
Features of AT89S51/52
- Compatible with MCS®-51 Products
- 8K Bytes of In-System Programmable (ISP) Flash Memory
- Endurance: 10,000 Write/Erase Cycles
- 4.0V to 5.5V Operating Range
- Fully Static Operation: 0 Hz to 33 MHz
- 256 x 8-bit Internal RAM
- 32 Programmable I/O Lines
- Three 16-bit Timer/Counters
- Eight Interrupt Sources
- Full Duplex UART Serial Channel
- Interrupt Recovery from Power-down Mode
- Watchdog Timer
- Dual Data Pointer
The relay is an electromagnetic switch, used to control the electrical devices. Copper core magnetic flux plays the main role here.
- The relay’s switch connections are usually labeled COM, NC, and NO:
- COM = Common, always connect to this; it is the moving part of the switch.
- NC = Normally Closed, COM is connected to this when the relay coil is off.
- NO = Normally Open, COM is connected to this when the relay coil is on
- A keypad is a set of buttons arranged in a block or “pad” which usually bear digits, symbols and usually a complete set of alphabetical letters. If it mostly contains numbers then it can also be called a numeric keypad.
- In order to detect which key is pressed from the matrix, the row lines are to be made low one by one and read the columns. Assume that if Row1 is made low, then read the columns.
- If any of the keys in row1 is pressed then correspondingly the column 1will give low that is if the second key is pressed in Row1, then column2 will give low.
Relay Driver (ULN 2003)
- ULN2003 is a high voltage and high current Darlington transistor array
- It consists of seven NPN Darlington pairs that feature high-voltage outputs with common-cathode Clamp diode for switching inductive loads.
- The ULN2003 has a 2.7kW series base resistor for each Darlington pair for operation directly with TTL or 5V CMOS devices.
- Current, Output Max:500mA
- Voltage, Input Max:5V
- Voltage, Output Max:50V
Liquid Crystal Display (LCD)
- Most common LCDs connected to the microcontrollers are 16×2 and 20×2 displays.
- This means 16 characters per line by 2 lines and 20 characters per line by 2 lines, respectively.
- The standard is referred to as HD44780U, which refers to the controller chip which receives data from an external source (and communicates directly with the LCD.
Working Principle of Password-Based Circuit Breaker
The proposed system is designed to control a circuit breaker with the help of a password on a keypad, which is connected to the project.
The controlling of this project can be done by an 8051 family microcontroller. A matrix keypad is connected to the microcontroller to enter the password. The entered password is compared with the stored password in the ROM of the microcontroller. If the given password is right, then only the line can be switched ON/OFF. The circuit breaker Activation/deactivation is indicated by a lamp (ON/OFF).
Further this project can be enhanced by using an EEPROM for the user to modify the password for a more protected system. It can also be interfaced with a GSM modem for remotely controlling the electronic circuit breaker through SMS.
Advantages of Password-Based Circuit Breaker
The advantages of password-based circuit breaker include the following
- It avoids electrical accidents to lineman
- This project is very simple and easy
- It can be built with commonly available components
Applications of Password-Based Circuit Breaker
The applications of password-based circuit breaker include the following
- It is used to ensure the lineman safety in electrical substations
- This system is used in houses and buildings
- To conserve the energy, it is used in public areas like hotels and shopping malls.
From the above information finally, we can conclude that this system provides a solution which can ensure that only the lineman can control the system and thus no possibility of someone else interfering the system. The lineman can simply work the loads from the major center rather than come to every circuit breaker source. Thus, it is an extremely useful, inexpensive and safe way of using circuit breakers.