The smart ultra-fast electronic circuit breaker is designed to work as an over current protection device. Conventional circuit breakers like miniature circuit breaker or a fuse is good at breaking the circuit when a short circuit fault occurs. But when an overload fault occurs, the tripping time is slow and depends on the percentage of overload. However, for sensitive loads it is very important to activate the tripping mechanism at the shortest possible time, preferably instantaneously. This project senses the current passing through a series element and the corresponding voltage drop is rectified to dc. This voltage is converted into a digital value and compared against a preset value by a microcontroller to generate an output that drives a relay to trip the load.   The unit is extremely fast and overcomes the drawback of the conventional circuit breakers. It uses a PIC Microcontroller. A microcontroller is one of the main components used here. The current transformers act as the sensor. The LCD displays the current status of the breaker. The current transformer senses the current passing through the main circuit and steps it down to a smaller value. The current in the main circuit can be sensed by taking the voltage drop across a resistor or by using an opto-coupler. But the current transformer is preferred as it is easy to use, avoids unnecessary energy losses and provides isolation. The current transformer will take the current in the main circuit and step it down to a very small value. This current is converted into voltage by passing it over a series resistor. This voltage is rectified and filtered and then given to the microcontroller.          

Objectives:

• To design a microcontroller-based fast-acting circuit breaker system.
• To detect overcurrent conditions using a current transformer (CT).
• To monitor the current continuously and provide quick fault detection.
• To trip the circuit breaker automatically during overload or short-circuit conditions.
• To display the breaker status and current information on an LCD.
• To provide electrical isolation between the main circuit and the control circuit using a CT.
• To improve the speed, reliability, and safety of power system protection.
• To reduce equipment damage and power interruption caused by electrical faults.

             

The main blocks of this project are:  

1. Power Supply.
2. Microcontroller.
3. Current Transformer.
4. Crystal oscillator.
5. Reset.
6. LED indicators.
7. LCD with driver.
8. Relay.
9. Potential Divider.

     

Software’s used:  

1. PIC-C compiler for Embedded C programming.
2. PIC kit 2 programmer for dumping code into Micro controller.
3. Express SCH for Circuit design.

         

Block Diagram:

             

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