Design And Implementation Of Detection System For Control Component Of Molded Case Circuit Breaker

Molded case circuit breaker is the most widely used type of low voltage circuit breaker.In the power supply and distribution system,it functions as on-off current control,overload short-circuit protection,and isolation.With the continuous development of science and technology,the requirements for the reliability of the molded case circuit breaker,uninterrupted power supply,and personal safety protection are also increasing.The molded case circuit breaker control component studied in this paper,as the core of the molded case circuit breaker,plays a major role in whether the molded case circuit breaker can realize its own protection function.Through the research on the basic function of the molded case circuit breaker and the three-stage protection function,an automated inspection system for quality control of molded case circuit breaker control components is designed,which realizes the detection function of the code switch setting,the overload long delay protection,the short circuit short delay protection and the phase failure protection.The hardware structure of the automatic detection system is mainly composed of industrial computer,data acquisition and control module,high current generation module,transformer module,power module and communication module.As the core of the industrial computer,the current and voltage signals in the system loop are collected through key components such as high-precision current transformers and sensors in the data acquisition and control module.According to the model specifications of the tested products,the large current generating module and the transformer module are controlled by switching devices such as contactors and relays to generate the required level of detection current to complete the inspection task.The high current generation module reduces the current regulation time and generates a wide range of detection current to meet different detection requirements by the cooperation with the coarse and fine adjustment voltage regulators,the autotransformer and the large current transformer.The five-station synchronous detection is adopted,and each station is composed of a transformer module,which further ensures the production capacity on the basis of improving the system detection efficiency.The detection system software is designed based on LabVIEW software development platform.Combined with flexible testing technology and modular design idea,the coding switch setting function detection module,overload long delay protection detection module,short circuit short delay protection detection module,phase failure protection detection module,etc.are designed respectively.Also,the system realizes the detection of corresponding functions.Aiming at the problem of misoperation caused by excessive non-periodic current signal during the operation of analog short-circuit transient protection function,a feasible method for calculating the power factor angle of short-circuit transient protection detection and phase selection is proposed by analyzing the phase difference of Hilbert transform.It lays a good foundation for the next step of short-circuit transient protection.