An Analysis and Simulation of Failure in Dower Connectors

The Journal of China Universities of Posts and TelecommunicationsVol. 9 ,No.3 , Sep.2002An Analysis and Simulation of Failurein Dower ConnectorsLUO Guo-ping directed by ZHANG Ji-gaoKey words : power commector ; analysis of failure ; parallel groorve clump ; finite element simulationPower connector , as one kind of fittings , ispresent obvious stress relaxation. Most samplesused to connect power equipment to conductor , con-( 95.6 percent ) are tarnished on their contact sur-ductor to wire or wire to wire in power lines. Owingfaces with thick film and deposited dust particles.to its simple structure ，easy installation and lowTherefore , failure of one connector is the combinedcost，bolt-type power connector-parallel grooveeffect of several failure reasons.clamp is widely used in overhead power transmission(2) Parallel groove clamps present seriousand distribution line. However , owing to high cur-stress fluctuation while connector temperaturerent load and harsh environment in China , there arevaries. Tension force of bolts linearly increases withstill some problems in application of this kind of con-the temperature rising. The force increasing rate isnector. So , some failure connectors replaced fromup to 43.98 N/ ? C. Hence , thermal cycling leadsclomestic overhead power lines are collected. Theto force fluctuation , which may also cause the cy-main reasons the failure are given out through inves-cling variation of electric contact area , the oxidationtigation into residual contact force , connection resis-on contact surface is accelerated and contact resis-tance , substrate quality , makeup , condition of con-tance moves u accordingly.tact interface and installation ，manufacture tech-(3) Vibration modal analysis by FEM showsnique etc. Then , the current test on parallel groovethat there are many kinds of vibration modes forclamps is carried out and finite element method isparallel groove clamps. The scope of mode frequencyused to simulate its failure process. Some importantis close to vibration of the overhead power line in-and new findings are summarized and listed as fol-duced by wind , which may be the cause of nearlylows :2/3 failure samples with obvious fretting morpholo-( 1 ) 45 failure bolt-type power connectors aregy on contact surface. For the frequency 0 ~ 300collcted from 20 different cities and regions in Chi-Hz , vibration modes of clamps include shaking ,na. Failure analysis results show that malfunction ofrocking and swaying of clamps and relative motion22.2 percent samples are mainly caused by stressbetween upper and lower covers. Vibration amongcorrosion , among them 80 percent samples are fromthe frequency scope 100 ~ 300 Hz should be noticedcoastal areas and frequent acid rain regions ; andbecause it may cause the relative displacement be-28.9 percent samples exist in obvious powder cor-twe中国煤化工, which results in theroded products with white color , among them 76.9MHcNMHGea,changeofcontactpercent samples are from coastal area and frequentposition and fretting on contact interfaces.acid rain regions. Moreover , 44.5 percent samples(4) The unbalance of contact resistance a-Biography :万访数据g , male , Ph. D Candidate , BUPT , iterested in the rescarch of analysis and simulation of filure in power conmoctors.80The Journal of CHUPT2002mong clamps and connected wires may cause electricthe connector can operate reliably or not. Undercurrent to pass through the bolts , which increaseshigh film resistance , the decreasing of contact areasthe temperature at the contact position betweencaused by the reduction of contact force may causewasher and connector covers , and accelerates elec-high temperature to rise rapidly. Therefore , main-trochemical corrosion. Meanwhile ，owing to thetaining enough contact force is the first key point toelectroplastic effect , bolts passing through electricobtain one reliable power connection. Meanwhile ,current may also accelerate its stress relaxation.high film resistance may greatly accelerate failure(5) Contact force , film resistance and fret-process and fretting ultimately leads to the failure ofting on contact surfaces are the key points whetherconnectors.From p.73Organizatio[J ] The Jourmnal of China Universities of[12] WU Xing-yu. Study on appointment system of accoun-Posts and Telecommunications ,2001 83)64- 67.tants[J ] Finance and Accounting ,2000 ( 8 ):4922Biographies :WU Li-feng( 1964 - ), male ,[13] WU Chang-hui , GUO Wu. Acounting monitoringfrom Shanxi Province ，graduated fromand control[ J ] Accounting Research ,2000 ( 5 ):48Xi an Jiaotong University in 1985 , profes--52.sor ,Xi' an Institute of Posts and Telecom-[14] LIU Yun-guo. Thinking on appointment system of ac-munications，interested in the research intocountants{ J ] Modern Accounting , 2000 h 2 ):46management theory , financial management48and accounting.[15] ZHAO Shuan-liang, WU Hong-bin. A study of im-pacts on China Post after China joins the World Trade中国煤化工MYHCNMHG