Q: What is the difference between Electronic circuit breaker and normal circuit breaker?
A: Normal circuit breaker is dependent on thermal bimetal lever trip mechanism, whereas Electronic circuit breaker is formed using current sensing element and comparators
Q: What is the role of microcontroller in this project?
A: The microcontroller is programmed to display the circuit breaker conditions.
Q: Will it auto return after fault (overload) clearance?
A: No, one has to restart the device, as it would toggle between on and off till overload condition is cleared.
Q: Which microcontroller is used in this project?
A: A 40 pin microcontroller from 8051 family is used in this project.
Q: Does this project works for short circuit faults or is only designed to protect against over load?
A: It works for both fault and over load.
Q: Up to which rating (load current) we can use this project without modification?
A: The load adjusted is for 100 watt run and 125 watt trip.
Q: If we want to use this project for higher rating (more than 5A) what are the modifications needed?
A: Higher load modifications are possible by use of CT.
Q: We used 1st lamp as rated load, 2nd lamp as over load. When 1st lamp (rated load) is on, measured value is 4.7V. But we fixed reference value more than 4.7V (say 6V). Why do we want to fix reference value more than measured value?
A: This is well explained in the documentation provided with project. As long as the relay is not on, the load is on. Thus for the relay not to be on, the output of the comparator has to be logic zero thus drive to the MOSFET gate is zero. For the output to be logic zero the inverting voltage (-) has to be greater than non-inverting (+). Therefore the fixed value at (-) is adjusted in such a way that it is greater than (+), the measured value in single load, resulting in output of the comparator at zero.
Q: What is the function of MOSFET in this project? Can we use BJT instead of MOSFET?
A: Here, MOSFET is used as a switch. BJT can be used, but that needs drive current and not voltage as required for MOSFET.
Q: What is the formula for calculating smoothing capacitor value?
A: There is some approximated formula .Peak to peak ripple voltage = Load current in amps / (2*line frequency in hertz *capacitance in farads). But as rule of thumb for 1 A current 1000uF is best. Thus it is load dependent.
Q: For the Potential Transformer, what rating of transformer did you use?
A: 230 volt to 12 volt 0.5 A ( 500mA) transformer is used.
Q: Is Current Transformer use possible as it has own specific type of transformer?
A: The CT desired for real time use can be done but cost would be highly unaffordable.