Computer Detection And Control Technology For Instantaneous Characteristics Test Of Moulded Case Circuit Breaker

ii Moulded case circuit breaker is one kind of protective electrical apparatus. If its reliability, especially instantaneous characteristics does not meet the need of production and life, it may bring trouble to users and even result in great economic loss. The study of its reliability is one important field at home and abroad. Because the work characteristic and failure mode are different from controlling electrical apparatus and other protecting electric apparatus, its reliability criterion and test method are different from other product. Therefore, it is very important to study the reliability test of moulded case circuit breaker.In the experiment of testing instantaneous characteristics for circuit breaker, the transient current exists in the experimental circuit because of the closing making angle, which has serious influence on the testing precision. Meanwhile,in the short circuit experiment of switch apparatus, in order to make that the aperiodic part of the current is the smallest, it is necessary to use a convenient phase selection making device with high accuracy. This paper points out the problems existed in the current circuit breaker's instantaneous characteristic test equipment controlled by computer and proposed the program for improvement. The phase selection making device is designed with a single-chip computer 80C196KC as its core. Also the paper designs the hardware and the software of the apparatus. The designs of hardware include the devise of executant and controller, the processing of voltage signal in phase,also the design of minimum system of the one-chip computer and discrete input signal. Because of the limitation of the SSR, the actuator chooses the SCR which responses very quickly. The single-chip computer controls the turn-on and turn-off of SCR through the optical coupler. At the same time, the electrical source voltage signal is turned into quadrate waveform which brings the interruption to the single-chip computer and detects its zero. In order to receive the power factor angle calculated by the upper computer, the communication interface circuits of single-chip computer is designed. In the software design, the programmes of the single-chip computer getting the closing making angle, serial port interrupt serving and exterior interrupt serving, accomplishing pahse selection making which uses the technology of computer timer interruption are written. The communication programme of PC is written by C .This device has been used on breaker's instantaneous characteristic test equipment, eliminating the transient current in the experiment effectly.