Table of Content

30 January 2022, Volume 0 Issue 1

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Overview

Review on Relay Storage Reliability Analysis and Accelerated Degradation Test

QIAO Qingyun, WANG Zhaobin, CHEN Kangning, LIU Baixin, ZHU Jiamiao

2022, 0(1):  1-6.  doi:10.16628/j.cnki.2095-8188.2022.01.001

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Relay is widely used,so it is of great significance to study its reliability.The storage reliability evaluation and life prediction of relays are important contents of relay reliability research.The failure mechanism of relay under long-term storage is briefly described.The influence of various environmental stresses on the storage reliability of relay and failure mechanism are analyzed.The several methods of relay reliability evaluation such as genetic neural network model and Bayes method are introduced.These reliability evaluation methods are analyzed and described.The application of accelerated degradation experiment method and grey theory model in the field of relay life prediction are summarized.Finally,the research on how to carry out accelerated degradation test and life prediction for high reliability relay products is prospected.

Research & Analysis

Effect of Vacuum Circuit Breakers Prestrike Characteristics on Inrush Current Suppression of Controlled Switching Capacitor Banks

PENG Jing, DENG Yunkun, WANG Ke, HUANG Jincai, GENG Yun, YAN Jing

2022, 0(1):  7-13.  doi:10.16628/j.cnki.2095-8188.2022.01.002

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The prestrike characteristics of vacuum circuit breaker (VCB) have a significant effect on the accuracy controlled switching capacitor banks.The effects of prestrike time and scattering in the VCB on the accuracy of the controlled switching capacitor banks are studied.The VCBs are cup-type AMF VCB and spiral-type TMF VCB.The prestrike time of the cup-type AMF VCB and the spiral-type TMF VCB is measured by experiments and its dispersion is calculated.Through 40.5 kV three-phase switching back-to-back capacitor bank simulation circuit,the inrush current amplitude of two controlled switching modes is calculated.Compared with the cup-type AMF VCB,the spiral-type TMF VCB has smaller prestrike time and dispersion.Compared with the phase selection method based on the closure time of the contact in the VCB,the phase selection method based on the prestrike time is more favorable to suppress inrush current.

Experimental Study of Contact Welding Failure under Inductive Load

HE Yubin, ZHANG Xu, REN Wanbin

2022, 0(1):  14-18.  doi:10.16628/j.cnki.2095-8188.2022.01.003

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Through the electrial performance simulation experimental system of contact material,the electrical life experiments of silver tin oxide contact under inductive load are carried out.The degradation of sensitive parameters such as arcing time,contact pressure and contact resistance are analyzed in detail.The failure process and failure mechanism of contact welding are confirmed by using the recorded contact voltage and contact current waveforms before contact welding failure.The drawn conclusions are valuable for improving the electrical life of relay and optimizing the contact material.

Study on Electrical Life Test of Miniature Circuit Breaker

HE Zhipeng, ZHAO Hu

2022, 0(1):  19-26.  doi:10.16628/j.cnki.2095-8188.2022.01.004

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An electrical life test device of miniature circuit breaker (MCB) is built,and the electrical life tests with MCB samples are carried out.Using the arcing voltage and arcing current signals collected in the test,the characteristic quantities that could reflect the degradation process of electrical life of MCB are extracted.In addition to the above works,an electrical life assessment model of MCB based on BP neural network is built,which used characteristic quantites as input parameters.The result of study shows that the extracted relative closing time and arcing voltage dropping time can greatly reflect degradation process of electrical life of MCB,and the electrical life assessment model has good assessment effect.

Influence Analysis of Overcurrent on Electromagnetic RCBO Leakage Characteristics

LI Luobin, SI Yingge, LIU Jin

2022, 0(1):  27-30.  doi:10.16628/j.cnki.2095-8188.2022.01.005

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Electromagnetic residual current operated circuit breakers with integral over current protection (RCBO) have strong anti-electromagnetic interference ability,but in the actual production process,when the instantaneous high current is applied to verify the instantaneous characteristics of the breaker,the leakage characteristics of the breaker may act at the same time,which makes it impossible to judge the instantaneous characteristics of the product.Whether the instantaneous characteristics are qualified or not will have a certain impact on the production of the breaker.Through simulation analysis,we find the mechanism leading to the failure and put forward suggestions for improving the design of the magnetic ring.

Study on Vibration of Contact Mechanism of Double Breakpoint Moulded Case Circuit Breaker in Limit Breaking Capacity Test

ZENG Yi, CHEN Luming, WU Jiansheng, LI Jidan, OUYANG Haijun, TONG Wei

2022, 0(1):  31-34.  doi:10.16628/j.cnki.2095-8188.2022.01.006

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In order to solve the problem that the moving and static contacts vibrate due to high-strength impact load or alternating load during the closing process of double breakpoint moulded case circuit breaker,a contact mechanism of circuit breaker is proposed.The test results show that the new circuit breaker contact mechanism increases the limit short-circuit breaking capacity from 100 kA to 150 kA,greatly reduces the arcing time and on-off time,and effectively improves the contact bounce problem.

Electrical Design & Discussion

Design and Research on Semi Controller of DC Circuit Breaker

SUN Guangtao, LI Shukun, JI Jianghui, WANG Xiaoli

2022, 0(1):  35-39.  doi:10.16628/j.cnki.2095-8188.2022.01.007

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A semi controlled,modular design,high stability and low cost DC circuit breaker controlgear is developed based on the DC circuit breaker to meet the control requirement of 10 kV DC distribution network project.Firstly,the conrol circuit according to the control principle of current transfer DC circuit breaker,and the working principle and implementation schcme of DC circuit breaker controller are analyzed in detail.Secondly,taking PLC as the core controller of DC circuit breaker,the controller of DC circuit breaker is divided into four different control sub modules.The PLC rapid detection and control of DC circuit breaker is developed through the local photoelectric conversion and optical fiber.Finally,the platform test and type test show that the response time and full current cleaning time of the DC circuit breaker taking PLC as the controller can meet requirements.

Optimal Design on Arc-Extinguishing System of Automatic Transfer Switching Equipment

ZHANG Haigen, CHENG Shaoyong, FU Zhichao

2022, 0(1):  40-42.  doi:10.16628/j.cnki.2095-8188.2022.01.008

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The arc-extinguishing system of automatic transfer switching equipment is optimized, the on-off problem is solved, and the on-off capacity of the product is improved.Based on the analysis of the structure,function and test results of the arc extinguishing system of a 250 A automatic transfer switching equipment, the arc striking structure is added in the arc-extinguishing system,and the spacing between the contact and the grid is reduced to form an improved scheme.Finally,the effectiveness of the improved scheme is verified by the on-off capacity tests.

Key Design of Circuit Breaker Controller for Prepayment Watt Hour Meter

FAN Jianguo

2022, 0(1):  43-46.  doi:10.16628/j.cnki.2095-8188.2022.01.009

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ing at the design of circuit breaker controller for the prepayment watt hour meter,the concept of motor driving stage model is proposed.Through the analysis of power supply design, drive design and load matching design, the reliability is improved on the premise that the functional indexes meet the requirements.The power supply adopts built-in on-off control type DC-DC, and the power parameters focus on the peak power of circuit breaker closing and opening.The drive adopts H-bridge chip with more advantages in volume and cost,and the built-in braking function provides the demand for accurate positioning.Through the test of national standards and enterprise standards and the practical application,the product function and reliability designed by this method meet the requirements,the unstable action problem of the low-temperature products is solved fundamentally.

Design and Simulation of Iron Core Current Transformer for High Precision Measurement

ZHOU Yingzi, JIA Feng, JI Huiyu

2022, 0(1):  47-50.  doi:10.16628/j.cnki.2095-8188.2022.01.010

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Based on the analysis of the working principle of current transformer,it is proposed that reducing the excitation current of transformer core is the key to improve the measurement accuracy of transformer.Through the theoretical analysis,simulation calculation and experimental test of transformer core structure and secondary coil turns,the effectiveness of the theoretical analysis and simulation design method is verified.

Modeling and Simulation

Simulation Analysis and Experimental Research on Magnetic Tripping Optimization of Miniature Circuit Breaker

HU Jinli

2022, 0(1):  51-56.  doi:10.16628/j.cnki.2095-8188.2022.01.011

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Miniature circuit breakers are generally short-circuit protected by magnetic tripping.Optimizing electromagnetic suction plays an important role in the design of miniature circuit breaker.The magnetic release model is established by using Creo software,and four kinds of moving iron core models with different structures and five kinds of yoke models with different structures are designed.The original model and optimization model are simulated and analyzed by using finite element software Ansys,and the electromagnetic suction and normalized acceleration of the moving iron core with different structures,different currents and different working clearances are obtained.The analysis results show that when the reduction volume of the moving iron core is small,or when the yoke length is shortened and the yoke thickness is increased,it is helpful to carry out the tripping action accurately and quickly.Finally,the instantaneous tripping experiments of three kinds of circuit breakers are carried out,and the experimental results are consistent with the simulation results,which verifies the correctness of the simulation results.

Dynamic Simulationand Research on Buffer Device of AIR Circuit Breaker Operating Mechanism of Based On ADAMS

ZHANG Chen, WU Weiyu, LIU Wanli, MA Shuangbiao

2022, 0(1):  57-62.  doi:10.16628/j.cnki.2095-8188.2022.01.012

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The buffer device of the operating mechanism can effectively absorb the excess energy of parts in the closing process of the air circuit breaker,so as to improve the service life and reliability of the air circuit breaker.The working principle and failure phenomenon of the operating mechanism of the air circuit breaker and the working principle of the buffer device involved are described.The three-dimensional model is established through UG and imported into the dynamic simulation software ADAMS to establish the simulation model,set the motion relationship and parameters in the motion process,focus on the comparison and analysis of the force conditions of vulnerable parts and the action characteristics of the operating mechanism before and after adding the buffer device,and shoot the action process of the operating mechanism and the mechanical life test of the air circuit breaker by the high-speed camera.The correctness of the simulation results and the effectiveness of the buffer device are verified,which provides a reference and basis for improving the mechanical life parameters of the air circuit breaker.

Fuse Temperature Simulation Calculation Based on Finite Element Analysis

ZHAO Aqin

2022, 0(1):  63-66.  doi:10.16628/j.cnki.2095-8188.2022.01.013

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The fuse in the ring cabinet operates under the high current environment for a long time,which can easily cause local temperature to rise,and in severe cases will destroy the insulation of the melt isolation cylinder,resulting in the burning of ring net cabinet.In order to reduce the fuse failure,the 3D simulation model of 6/12 kV fuse is established by finite element software,and the temperature field simulation under different operating conditions is calculated.The results show that the outer wall temperature of the fuse is the highest in the middle position.It is gradually decreasing along the axial symmetry,and the ambient temperature does not affect the temperature difference of the outer wall.The temperature difference of the outer wall of the fuse in the low load,stable and overload fusing stage is respectively less than 9 ℃,9~11 ℃ and 24~42 ℃.Therefore,in practice,the temperature difference between the outer wall of the fuse can be used to judge its operating state,which is of practical significance to improve the operating reliability of the fuse.

Electromagnetic Force Analysis on Current Limiting Unit of High Temperature Superconducting Current Limiter

YUE Danyang, ZHUANG Jinwu, WU Jin, LI Siguang, LU Liqiang

2022, 0(1):  67-72.  doi:10.16628/j.cnki.2095-8188.2022.01.014

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At the moment of a short circuit in the power grid,the short-circuit current may rapidly rise to hundreds of kiloamps.Using the zero resistance characteristic of superconducting tape,the designed superconducting current limiter can quickly cut off the fault current to protect other components.Because the superconducting tape is inevitably subjected to electromagnetic force after current is applied,the electromagnetic force is simulated and analyzed to study the distribution characteristics of its magnetic field and electromagnetic force.The radial force of the superconducting tape disc has the strongest force on the outermost coil and is the expansion force,the innermost coil is the smallest,the direction is related to the number of tape discs.The axial force of the middle disc is the least,and the axial force of the coils on both sides is the least.The size is the same,the direction is opposite,and the axial force of the outermost coil of the two disks is the largest.It can provide reference for the structural design and fatigue analysis of the tape plate.

Application

Application of High Grade Silver Tin Oxide Contact Material in AC Contactor

XIAO Tifeng, WANG Jian, ZHU Yingping, HU Juejia

2022, 0(1):  73-78.  doi:10.16628/j.cnki.2095-8188.2022.01.015

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A series of high-grade AgSnO₂ and AgCdO electrical contact materials were prepared by different manufacturing processes.The physical properties and microstructure of AgSnO₂ synthesized by pre-oxidation and AgCdO prepared by various processes (internal oxidation and pre-oxidation) were compared and analyzed.The performance of different current levels AC contactor of service cycle life and contact temperature rise and so on were also carried out and the corresponding mechanism of life failure was also investigated.The experimental results show that the high grade AgSnO₂(15) electrical contact material has better service life compared with the traditional high grade AgCdO material in the application test of low current grade 32 A and high current grade 95 A contactors.