Automatically Resetting Circuit Breaker

Circuit Breakers are one of the most important component in the home circuitry. They are very essential in order to protect the house hold devices from voltage fluctuations. Circuit breakers have evolved very much from a simple fuse wire to different types of MCBs. We thought for some ideas for our mini project, which is to be done as part of our syllabus, and to our luck we were suggested to work on some thing by our senior. Idea was simple to design and implement a circuit breaker that will RESET AUTOMATICALLY!!!

So why some thing that already exists but with a few modifications? The world is now becoming automated. Everything around us is automatic in someway or another. So we think that this could simply add up to that range of automated devices. When we did a search we found that this one is NOT NEW! Actually we found some products in online which was similar to this type. Then WHY proceed with this idea? What we found online was a bit costlier (well…still they fit to the definition “miniature” and ours is not so small…:D) . So we thought we’d design something to achieve the same with some low cost components.

As said before, the project was as part of our course. I’m extremely thank full to my team mates. This one’s a result of team work…:) Another advantage WE obtained through this project was that it had applications from almost everything we learned till the sixth semester.



We started this by creating a block level representation of the overall system. The over all system working is simple. The system has two paths to connect the input section to the home devices and two separate control circuits. The power is transferred through the main line in the normal condition. When exceeds a certain value (we took a max. of 3Amps.) control circuit associated with the main line triggers and cuts the devices from main line and a secondary line is connected through which a proportionally reduced current is transferred. Here too with help of a current sensor and a control circuit, the current is checked and the line is switched back to normal line when current is normal.

When choosing a current sensor, we came across different options like using a resistor, current sensor ICs etc. But we chose current transformers for the purpose for their low cost and reliability. We designed amplifiers and buffers by using Op-amps (And thanks to Texas Instruments that we got the ICs as samples from them…:) )  We used simple diode rectifiers and an OR gate as the decision device (u can understand why OR is chosen assuming a high is obtained from the control during overload). Now when coming to the relay part, we decided to use a solid state relay as its faster than the electromechanical relays and they avoid sparking. But it didnt worked well and we still couldn’t figure it out and we had to use the electromechanical relay to complete the project.

completed circuit


The completed work is as in the figure above.  The entire system is a result of teamwork and i express my great thanks to my team mates for their parts in the project and our senior who gave us this wonderful idea…:)


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