Design Of Single-Pole Solid-State Circuit Breaker

In the power system of transmission and distribution, the circuit breaker switches areindispensable as a kind of protect device. With the rapid development of power electronicdevices, on the late of 1970, a new baby of circuit breaker come into the world: solid-statecircuit breakers. Compared to the traditional mechanical circuit breaker, because of theirsmall size, breaking fast, no arc when turn on or off, etc. Solid-state circuit breaker hasbeen rapidly development. However, solid-state circuit breakers are expensive, so thecurrent application in the market the traditional mechanical circuit breakers are used more.For that reason, it is necessary to design a new kind of solid-state circuit breaker which isnot expensive in the filed of civil use.Through the comparison of varieties of power electronic devices, using IGBT as aswitching device of solid-state circuit breaker by considering both the function and theprice. Developed solid-state circuit breaker with the previous difference is that, throughresearch and analysis of the PTC thermistor materials, putting IGBT and PTC thermistorcombination of together as solid-state circuit breaker switch. Because of theresistance-current characteristics of PTC thermistor material, in the case of the ratedcurrent, the PTC thermistor is equal to a conductor of the circuit, which resistance is small,will not affect the normal use of electricity basically. But once there is a short-circuit faults,resistance of the PTC thermistor is increased exponentially, which plays an important roleboth in restricting short-circuit current and protecting the load.Considering the solid-state circuit breaker has different breaking strategy under thedifferent condition of over-current, using PIC16F876A chip as a kernel controller, designeda real-time signal acquisition system of the current. In addition,design the rate of change ofthe current acquisition circuit. The multisim10 software simulation results show that therate of change of the current was used to detect short-circuit current signal can be greatlyimprove the speed of fault signal detection.According to the hardware and the software design, produced a prototype of single-pole solid-state circuit breaker and do the corresponding field experiment. Theresults show that the prototype meet with the requirements, achieved the desired resultsbasically.