Fang Yao

Improved Fuzzy C-Means Based on the Optimal Number of Clusters

According to the number of cluster centers, initial cluster centers, fuzzy factor, iterations and threshold, Fuzzy C-means clustering algorithm (FCM) clusters the data set. FCM will encounter the initialization problem of clustering prototype. Firstly, the article combines the maximum and minimum distance algorithm and K-means algorithm to determine the number of clusters and the initial cluster centers. Secondly, the article determines the optimal number of clusters with Silhouette indicators. Finally, the article improves the convergence rate of FCM by revising membership constantly. The improved FCM has good clustering effect, enhances the optimized capability, and improves the efficiency and effectiveness of the clustering. It has better tightness in the class, scatter among classes and cluster stability and faster convergence rate than the traditional FCM clustering method.

Research on Optimization Technology of Electromagnetic Transformer

Taking the typical electromagnetic voltage transformer JDCF-110 as the research object, according to the performance characteristics, the optimization mathematical model is set up. Ant colony algorithm is selected as optimization algorithm. With the cost as objective function, the settings of key parameters are studied on in optimization design. By use of Visual C++ language, the optimization design software of electromagnetic voltage transformer is finished on the plat of Windows XP. According to users requirement, the basic design and the optimized design of electromagnetic voltage transformer can be conveniently and quickly realized.

Study on Micro-Deformation Monitoring Technology of Contacts for Electric Connectors

Using optical fiber sensing technology to monitor the micro-deformation of the contacts for electric connectors. In this paper, the test scheme on the micro-deformation of the contacts of electric connectors is established; the micro-deformation test circuit is designed; and micro-deformation detecting test of the contacts for the electrical connectors is conducted under different temperature stresses conditions. Finally, the feature of the deformation affected by high temperature is analyzed.

Numerical Analysis on Temperature Field of Electric Connectors

The steady-state thermal analysis models are established based on the thermal analysis of the Electric connectors. With the consideration to the internal heat conduction and the convection cooling, the three-dimensional solid model is imposed by the reasonable loads and boundary conditions and analyzed by ANSYS thermal analysis module. The numerical analysis is made on the temperature field of a certain type of Electric connectors at different environmental temperature and different working current. The simulation results are compared with the monitoring test data.

Research on Grey Prediction of Electromagnetic Relay Contact Resistance

When the relay contacts are switched on the load circuit, contact pairs on-state directly reflects the relays reliability, and it also indirectly reflects machine performance of the relay. Therefore, the static contact resistance is one of the key features of the relays state estimation and failure warning. However, the contact resistance of the relay contact is uncertainty characteristics, small-scale sequence trend model is difficult to obtain an ideal prediction performance, and therefore grey model which based on small-scale sequence for prediction of electrical contact reliability of the relay is drawn on. Using the static contact resistance measurement value of the relay contact resistance as training samples to set up GM (1, 1) model and obtaining development grey number a and endogenous control grey number b by least square method, so as to get differential equation of original datas predicted value and then forecast the original data. In order to improve the prediction accuracy and weaken the influence of randomness, sliding smoothing formula to the original data is used to get improved prediction model. By comparing the difference between the accuracy of improved model and not improved model, it concludes that the improved model has possibility and accuracy higher.

Research on Voltage and Current Monitoring System for Circuit Breaker

This article develops the automatic test system of voltage and current dynamic waveform for circuit breaker. The system has the automatic monitoring, the storage and the display function of contact voltage and current waveform of circuit breaker in switching process. And then, it also designs the hardware and software of voltage and current dynamic monitoring system for miniature circuit breaker: the hardware circuit of this test system mainly consists of the detection circuit and the data acquisition circuit of current and voltage. And the software system, which mainly consists of control program, data acquisition program and data processing program, is programmed under the condition of LabVIEW. At last, it carries on the real-time monitor to the voltage and current waveform at the both ends of the circuit breaker, especially for the waveform during the switching process, which contributes to study the arc energy and contact wear of circuit breaker.

Influence of Eddy Current Effect on the Circuit Breaker Contact Mechanism Heat Loss

With the three-dimensional field analysis software Ansoft Maxwell 3D, the three-dimensional finite element model of the contacts pair is established. They belong to a kind of miniature circuit breaker. The simulation is carried out in the transient magnetic field. Under the condition with or without eddy current effect, we get the position and numerical solution of the contact mechanism heat loss under different short-circuit current.

Research on Reliability Test Technology of Overload Relay

The reliability test of the overload relay is an important way to find out weak parts and improve the reliability of products. So reliability test technology is of great significance. The reliability test method of overload relay is studied on. By use of reliability tester, the reliability test for the typical productsJRS1D-25 is carried out. According to the test result, the reliability analysis is developed from two aspects of product structure and material characteristics. The failure reasons of the overload relay are found out and the improvement measures are put forward.