Password Based Circuit Breaker

Password Based Circuit Breaker is a simple project that helps in controlling the electrical lines with the help of a password.

Due to a lack of communication between the electrical substation and maintenance employees, electrical accidents to linemen are on the rise while fixing electrical lines. This initiative provides a solution to this problem by ensuring the safety of linemen. The control (ON/OFF) of the electrical wires is delegated to the line man in this suggested system. This project is set up so that maintenance personnel or linemen must enter a password to turn on or off the electrical line.

Now, if there is a fault in an electrical line, the line guy will turn off the power supply to the line by entering the password and repair the line comfortably, then return to the substation and turn on the power supply to the line by entering the password. Each electrical line has its own set of passwords.

Before learning more about this circuit, take a look at this intriguing article: Locking system based on a password


  • Construction and Output Video
  • Block Diagram
  • Principle of Operation
  • Circuit Diagram of Password based Circuit Breaker
  • Components Required
  • How to Design Password based Circuit Breaker Circuit?
  • Algorithm 
  • Simulation Video
  • How to Operate the Password based Circuit Breaker Project?
  • Download Project Code
  • Advantages
  • Applications

Construction and Output Video

Block Diagram

Principle of Operation

The 8051 microcontroller is the circuit’s key component. The password is entered using a 44 keypad in this project. The entered password is compared to a list of predetermined passwords. If the password is accurate, the relevant electrical line is activated or deactivated. Each electrical wire is given its own password in this project. The load indicates line activation and deactivation (circuit breaker) (Light Bulbs).

Circuit Diagram of Password based Circuit Breaker

Password Based Circuit Breaker

Components Required

  • 8051 Microcontroller (AT89C52)
  • 8051 Development Board
  • 8051 Programming Board (Programmer)
  • 4 x 4 Matrix Keypad
  • 4 – Channel Relay Module
  • 16 x 2 LCD Display
  • 10KΩ Potentiometer
  • 4 Loads (Light Bulbs)
  • Power Supply
  • Connecting Wires
  • If 8051 Development Board is not used, then you need
    • 0592 MHz Crystal
    • 2 x 33pF Capacitor
    • 2 x 10KΩ Resistors (1/4 Watt)
    • Push Button
    • 10µF Capacitor (Electrolytic)
    • 1KΩ x 8 Pull – up Resistor Pack
  • If Relay Module is not used, then you need (components mentioned for one load)
    • 5V or 12V Relay
    • 1KΩ Resistor (1/4 Watt)
    • BC547 NPN Transistor
    • 1N4007 PN Junction Diode

How to Design Password based Circuit Breaker Circuit?

The 8051 series controller (AT89C52), 44 Matrix Keypad, 16 x 2 LCD Display, 4 – Channel Relay Module, and Four Loads are all included in the above circuit. The LCD data pins are connected to PORT1, while the control pins RS, RW, and EN are connected to P3.0, GND, and P3.1. The LCD is utilised to display information about the load in this case.

The microcontroller’s PORT2 is connected to the keypad. The Keypad’s four row pins are connected to P2.0 through P2.3, and the four column pins are attached to P2.4 through P2.7. We must enter the password using this keypad.

Four Lamps (acting as Electrical Lines) are connected to P0.0 to P0.3 through the 4 – Channel Relay Module. These are used to indicate circuit breaker state (Light ON – Line Active and Light OFF – Line Not Active).

If you are not using the Relay Module, then you need to use 4 BC547 NPN Transistors (along with its current limiting base Resistor) in order to drive the relays.


  1. Initially declare the PORT1 to LCD data pins and its control pins RS and E to P3.0 and P3.2 and P3.7 respectively. Also declare PORT2 to keypad and use P0.0, P0.1, P0.2 and P0.3 to loads.
  2. Initially display “enter password” on LCD.
  3. Now read the five digit password from the user.
  4. Compare the entered password with stored password.
  5. If the password matches, correct then ON or OFF the particular load and display line or load status on LCD.
  6. If the password is wrong, then display “wrong password” on the LCD.
  7. After some delay, again ask to enter password.

Simulation Video

How to Operate the Password based Circuit Breaker Project?

  1. Write the program to the Password based Circuit Breaker in Keil software and create .hex file.
  2.  Burn program to the controller with help of 8051 Programming Board and Willar Software.
  3.  Now give the connections as per the circuit diagram.
  4. While giving the connections, make sure that there is no common connection between AC and DC supplies
  5. Use 5V power supply circuit to provide regulated 5V DC to the controller.
  6.  Switch on the both AC and DC supplies.
  7. Now relay output pins gets 230V. So, do not touch the load connected pins.
  8. LCD displays “enter password”.
  9. Enter the password with help of keypad.
  10.  Now, if the password is correct, then circuit breaker changes its state (i.e. if it is already ON, now it becomes OFF and if it is already OFF, now it becomes ON) and displays line (or load) status on LCD.
  11.  If the password is wrong, then the LCD displays “wrong password”.
  12. After some time, the microcontroller asks to enter password by displaying “enter password”.


  • Avoids electrical accidents to line man
  • Project is simple and easy
  • Uses commonly available components


  • 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. 
  • Can also be used as Password based electrical appliance control or Password based Load Control system.

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