Table of Content

30 January 2023, Volume 0 Issue 1

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Overview

Thoughts on Development of Low Voltage Electrical Apparatus Industry Under Carbon Peaking and Carbon Neutrality Background

YIN Tianwen, GAO Xiaotian

2023, 0(1):  1-7.  doi:10.16628/j.cnki.2095-8188.2023.01.001

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Achieving “carbon peaking and carbon neutrality” is one of the national policies for Chinese future development,and building a novel power system is one of the important supports for achieving the goal.“Carbon peaking and carbon neutrality” strategy and the development background,opportunities and challenges faced by the low voltage electrical apparatus industry are deeply analyzed.And on this basis,the development strategy of the industry in the new period is proposed,which is to build a “highly autonomous power distribution system”.The key technologies,key equipment and standard system architecture in this system are sorted out.Finally,the development direction of the industry in the next stage is analyzed and prospected.

Overview on Integration Technology of Low Voltage AC Electromagnetic Apparatus

YE Hongwei, MIAO Xiren, ZHANG Linhui, ZHUANG Shengbin

2023, 0(1):  8-15.  doi:10.16628/j.cnki.2095-8188.2023.01.002

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With the continuous expansion of power grid capacity and the development of smart grid,higher requirements are put forward for the reliability and safety of power supply.The performance of low voltage switching devices and the coordination between various switching devices are closely related to the reliability of power system.Starting from improving the reliability requirements of power system control and protection functions,the present situation,technical requirements and shortcomings of electromagnetic apparatus commonly used in the main circuit of low voltage distribution network such as contactors and circuit breakers are expounded,and the necessity of the development of integration technology of low voltage electromagnetic apparatus is pointed out.The research status of the new principle structure technology at home and abroad and three realization forms of this technology are summarized.The necessary intelligent control technology in the integrattion process is analyzed,including fault identification and optimal control of motion process.Finally,the trend of low voltage electromagnetic apparatus integration technology is discussed.

Research & Analysis

Study on Effect of Contact Splash on DC Breaking

XU Junshuai, LI Jing, LIU Shuxin, PENG Shidong

2023, 0(1):  16-23.  doi:10.16628/j.cnki.2095-8188.2023.01.003

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In order to study the effect of contact splash on DC breaking,the model of arc-contact mutual coupling was established by adding equilibrium equations.The morphology change of the contact surface after splashing was simulated by using the dynamic grid technology and arc pulling simulation was performed.The results show that the increase of the contact surface temperature promotes the thermoelectric emission on the cathode surface and increases the current density.The distortion of the electric field strength between the contacts after splashing is not conducive to the breaking of the arc,but the existence of a certain concentration of metal vapor is conducive to the extinguishing of the arc.

Experimental Research on Static Attraction Force Characteristic of Solenoid Electromagnet

SU Bin, ZHANG Chao, REN Wanbin

2023, 0(1):  24-27.  doi:10.16628/j.cnki.2095-8188.2023.01.004

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The static attraction force characteristic is directly related to the motion process and coil power consumption of electromagnets.A novel test device for the static attraction force measurement of solenoids electromagnet is specially designed,and the relationship between the dynamic current of the coil and the electromagnetic force is analyzed.Finally,the effects of magnetic gap and coil voltage on the electromagnetic force are experimentally studied.

Two-Step Identification Method of Breakpoint in Opening and Closing Vibration Process of HV Circuit Breaker

CHEN Hao, XU Weilun, SHA Haoyuan, YAO Longhua, WANG Weiliang, XU Peng

2023, 0(1):  28-33.  doi:10.16628/j.cnki.2095-8188.2023.01.005

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Mechanical fault information is rich in the vibration signal during the closing and opening process of HV circuit breaker,the study on the mechanical diagnosis of circuit breaker based on vibration signal information is of practical value in the engineering.To promote the efficiency of the signal acquisition during the closing and opening process of HV circuit breaker,a two-step identification method of the breakpoint in closing and opening vibration process of HV circuit breaker is proposed.Firstly,the sudden change is preliminary detected by the dynamic heteroscedasticity test in the first step.Secondly,the breakpoint is detected by conditional variance test based on the potential mutation moment set in the second step.Moreover,the switching mechanism of the signal acquisition channel is proposed,and the acquisition efficiency is promoted without the additional hardware.Finally,the practical application in Jiangsu power grid verifies the effectiveness of the proposed two step identification method.

Optimization on Fracture Resistance of Shading Ring of AC Contactor

QI Xiaojun, FENG Weijie

2023, 0(1):  34-41.  doi:10.16628/j.cnki.2095-8188.2023.01.006

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Aiming at the problem of the vibration of the moving circuit unit caused by the fracture of the shading ring in the AC contactor,the fracture resistance of the shading ring is optimized by reducing the impact of collision energy on the shading ring.The assembly stress of the shading ring is analyzed by the finite element method,and then the fracture mechanism of the shading ring is analyzed.The simulation results are verified by the mechanical durability test of the AC contactor.The influence of the shading ring assembly,turns of coil unit,reaction force of electromagnetic system and moving circuit unit structure of electromagnetic system on the fracture resistance of shading ring is studied by simulation.The results are verified by experiments.The results show that the proposed optimization scheme reduces the impact of collision energy on the shading ring,improves the fracture resistance of the shading ring,and provides the guidance for the design and optimization of the shading ring of AC contactor.

Analysis on Effect of Load on Arcing Characteristics of DC Circuit Breaker

LIN Xinde

2023, 0(1):  42-49.  doi:10.16628/j.cnki.2095-8188.2023.01.007

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Firstly,the arc extinction principle of DC circuit breaker is described based on the differential equation of DC circuit model,and the influence of load time constant on DC arc energy,arc voltage and arcing time is analyzed.Secondly,the arc extinction process and the characteristics of arc voltage under different time constants (5 ms,10 ms) are analyzed by the two-dimensional arc model simulation.It is obtained that the time constant has a decisive influence on the arcing time,flashover and peak arc voltage.The simulation results are verified by the physical experiments.Based on the research on the influence of load on the arc characteristics of DC circuit breaker,a certain reference is provided for mastering how to quickly extinguish the arc,reducing the ablation of the arc on the contact,and improving the breaking reliability of DC circuit breaker.

Research on Residual Stress of Thermal Bimetal After Welding and Its Elimination Method

ZHU Haibo, YANG Yu, XU Shengguo

2023, 0(1):  50-54.  doi:10.16628/j.cnki.2095-8188.2023.01.008

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By analyzing the causes of thermal bimetal residual stresses and its influence on the product,the method of high temperature heat treatment to eliminate the residual stress of the thermal bimetallic is studied.It is concluded that the residual stress and heat treatment cycles has certain negative correlation relationship,and the calculation formula for reference is established.The theoretical formula is further tested to verify its high effectiveness.

Simulation Calculation of Dynamic Characteristics of Circuit Breaker Operating Mechanism Considering Friction

LI Hongfei, MA Shaohua

2023, 0(1):  55-61.  doi:10.16628/j.cnki.2095-8188.2023.01.009

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In order to improve the accuracy of finite element simulation calculation of the dynamic characteristics of the circuit breaker operating mechanism,the friction force influence of the rotating transmission mechanism is considered when solving the reaction force of the circuit breaker operating mechanism.The contact force model and friction circle are introduced to analyze the force of the transmission mechanism considering the friction,and the reaction force characteristic curve on the moving iron core considering the friction is obtained.Compared with the simulation results without considering the friction,the deviation between the simulation results of the dynamic characteristics of the mechanism and the actual experimental results is significantly reduced.

Analysis of Electromagnetic Voltage Transformer Ferroresonance Characteristics

CUI Juyong, WANG Shuai, ZHAO Zijian, WANG Guanyu, ZHAO Zhenyang

2023, 0(1):  62-65.  doi:10.16628/j.cnki.2095-8188.2023.01.010

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In the nongrounded neutral system,the ground capacity and the excitation inductance of primary windings of a Y0 type electromagnetic voltage transformer compose a loop to the ground.Due to over-voltage and over-current operation in the system,the ferromagnetic element of the voltage transformer is saturated,which causes the resonance and easily leads to the damage of the transformer.A practical case analysis and simulation calculation are involved to certify the conditions of ferrosonance caused by the saturation of the core of the electromagnetic voltage transforme and the harmonic elimination measure.Thereafter,the improvement suggestions is proposed for the existing test standards of excitation characteristics of the electromagnetic voltage transformer,which provide a basis for the equipment selection and fault analysis.

Electrical Design & Discussion

Study on Welding Technology of Air Circuit Breaker Contacts with High Current

WANG Xueliang

2023, 0(1):  66-68.  doi:10.16628/j.cnki.2095-8188.2023.01.011

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The welding technology of electric contacts of Emax series air circuit breakers welded with BAg15CuP brazing filler metal is studied,and the welding performance is compared with that of BAg40CuZnCd brazing filler metal.By the metallographic analysis,the optimal welding technology of BAg15CuP brazing filler metal in the electric contacts of high current air circuit breakers is obtained,and the appropriate high-frequency induction welding coil is researched.The technology improvement of high-frequency induction brazing of high current air circuit breaker electric contacts is successfully completed.

Analysis of Relay Contact Sticking Fault in Circuit Breaker Control System

SHI Jian, ZHOU Zhaoqing, YUE Feng

2023, 0(1):  69-72.  doi:10.16628/j.cnki.2095-8188.2023.01.012

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Electromagnetic relay is commonly used in tripping on/off a circuit breaker,where it can be used as a circuit holder.A case of the relay contact sticking fault found in the relay substitution test process is analyzed.It is demonstrated that the relay structure design caused more bounces and longer time after power on.The test shows that the relay bounce may lead to the contact sticking when the working current of tripping the circuit breaker closing coil is large.As a conclusion,the relay used in tripping on/off circuit breaker circuits shall check its bounce time and bounce count to avoid sticking problem.

Design and Application of Air Circuit Breaker Double-Key Lock

WANG Yuxiang, YUAN Bo, LINGHU Shaojiang, LIU Mi, HE Xin, CHENG Liyu

2023, 0(1):  73-77.  doi:10.16628/j.cnki.2095-8188.2023.01.013

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The key lock attachment of the air circuit breaker can provide the protection for the power system's power safety and energy saving.The structure and working principle of the existing air circuit breaker key lock are introduced,and some examples of its application scenarios in the power supply system are given.On the basis of the existing key lock,the design is improved,and a newstructure of the double key lock is proposed,which plays an important role in the power outage maintenance,power allocation and prevention of personnel misoperation in some power supply systems with a large number of power supplies and complex interlocking logic.

Research and Application of Testing Device for Comprehensive Performance of External Circuit Breaker

ZHENG Jinbo, ZHENG Lejiang, YAN Xiangkun

2023, 0(1):  78-83.  doi:10.16628/j.cnki.2095-8188.2023.01.014

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In view of the need to build different test environments for the external circuit breaker comprehensive performance testing in the laboratory,a multifunctional integrated external circuit breaker comprehensive performance testing device is designed to solve the problem of repetitive wiring between different test items.By analyzing the technical requirements of China Southern Power Grid Company Limited for external circuit breakers,the device uses computer,PLC,voltage regulator,relay,signal acquisition circuit and other components to design the software and hardware of the detection items with the similar detection principles,and complete the data acquisition analysis and conclusion determination of voltage,current and time signal changes.The device can be selected for level control,drive ability,leakage current,automatic closing time and other test items,which can effectively solve the problem of different test items need to build different test environment,have the characteristics of simple structure,high efficiency and reliability.