Pub Date : 1900-01-01DOI: 10.1109/HOLM.1999.795942
Xueyan Lin, Yi-lin Zhou, Ji-gao Zhang
The environmental effects on several contact platings including gold, silver, nickel and tin were studied after investigating the morphology, composition and fretting behavior of natural corroded products, which were formed in Shanghai, China after long-term indoor air exposure. Corrosion formed on all of the testing coupons are found as discrete islands rather than continuous layers as predicted. Not only the protrusive core product but also one or more dark rings centrically surrounding the core are seen on gold plated coupons. Micro-observation on the ring shows that it is formed by accumulated and discrete islands similar to that of the core. The height of corroded products on the ring is much lower than that of the core. The composition of corroded product on the ring is similar to that of the core. Fretting across the dark ring also causes high contact resistance. Preliminary investigation shows that this may cause sudden and rapid high impedance and error codes in telecommunication systems.
{"title":"Island growth of corroded products on various plated surfaces after long-term indoor air exposure in China","authors":"Xueyan Lin, Yi-lin Zhou, Ji-gao Zhang","doi":"10.1109/HOLM.1999.795942","DOIUrl":"https://doi.org/10.1109/HOLM.1999.795942","url":null,"abstract":"The environmental effects on several contact platings including gold, silver, nickel and tin were studied after investigating the morphology, composition and fretting behavior of natural corroded products, which were formed in Shanghai, China after long-term indoor air exposure. Corrosion formed on all of the testing coupons are found as discrete islands rather than continuous layers as predicted. Not only the protrusive core product but also one or more dark rings centrically surrounding the core are seen on gold plated coupons. Micro-observation on the ring shows that it is formed by accumulated and discrete islands similar to that of the core. The height of corroded products on the ring is much lower than that of the core. The composition of corroded product on the ring is similar to that of the core. Fretting across the dark ring also causes high contact resistance. Preliminary investigation shows that this may cause sudden and rapid high impedance and error codes in telecommunication systems.","PeriodicalId":299141,"journal":{"name":"Electrical Contacts - 1999. Proceedings of the Forty-Fifth IEEE Holm Conference on Electrical Contacts (Cat. No.99CB36343)","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116682296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/holm.1999.795923
W.W. Chen, L. A. Dorrell
In most existing low current interruption devices, the current is interrupted using only separating contacts. By adding a ceramic PTC (CPTC) element in parallel with the contacts, 100% of the interruption energy can be converted to heat, eliminating the are totally. The initial voltage across the contacts must be less than a pre-determined value in order to shunt all of the current to the CPTC. The cold resistance of the CPTC is the main factor in determining the initial voltage across the contacts and the current at which the CPTC trips. Two types of ceramic PTC devices were tested, with cold resistances of 16 and 32 ohms respectively. In the case of each device, at 300 Vdc and 1.0 A, all of the interruption energy was consumed by the CPTC. At 300 Vdc and 1.5 A, the 16 Ohm CPTC successfully absorbed 100% of the interruption energy; however, the 32 Ohm CPTC device had a slightly lower performance at 98%. Because of the elimination of arcing, use of the CPTC in low current interruption devices will result in reduced contact size and increased operation cycles. It will also provide an arcless interruption for application in hazardous conditions.
{"title":"A method to achieve arcless interruptions in low current circuits","authors":"W.W. Chen, L. A. Dorrell","doi":"10.1109/holm.1999.795923","DOIUrl":"https://doi.org/10.1109/holm.1999.795923","url":null,"abstract":"In most existing low current interruption devices, the current is interrupted using only separating contacts. By adding a ceramic PTC (CPTC) element in parallel with the contacts, 100% of the interruption energy can be converted to heat, eliminating the are totally. The initial voltage across the contacts must be less than a pre-determined value in order to shunt all of the current to the CPTC. The cold resistance of the CPTC is the main factor in determining the initial voltage across the contacts and the current at which the CPTC trips. Two types of ceramic PTC devices were tested, with cold resistances of 16 and 32 ohms respectively. In the case of each device, at 300 Vdc and 1.0 A, all of the interruption energy was consumed by the CPTC. At 300 Vdc and 1.5 A, the 16 Ohm CPTC successfully absorbed 100% of the interruption energy; however, the 32 Ohm CPTC device had a slightly lower performance at 98%. Because of the elimination of arcing, use of the CPTC in low current interruption devices will result in reduced contact size and increased operation cycles. It will also provide an arcless interruption for application in hazardous conditions.","PeriodicalId":299141,"journal":{"name":"Electrical Contacts - 1999. Proceedings of the Forty-Fifth IEEE Holm Conference on Electrical Contacts (Cat. No.99CB36343)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117207125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1999.795930
Guoping Luo, Jian-guo Lu, Ji-gao Zhang
Bolt-type power connectors are widely used in China due to their simple structure and low cost. However, investigation shows that this kind of power connectors needs continuous maintenance and frequent replacement. By analyzing the failed connectors that were collected from different cities and sites, high connection resistance of most samples was found. Clearly high temperature has been occurred at each connector. Bolts of nearly 45% of the testing connectors appeared loosening, which caused low contact pressure, evidently the bolts were stress relaxed. Even the bolts were rusted and locked, the strand wires could still rock in the grooves of the connectors. Sliding and fretting tracks were clearly observed and appeared different kinds of morphologies. Serious contaminants and corrosive film covered on the groove surfaces, which caused high temperature rise and further enhanced stress relaxation. Surfaces of almost 58% samples preserved obvious melting or welding appearance, some of them were even burnt out, evidently there were gaps between wires and connector. Therefore, the structure of the bolt type power connectors can hardly stand for the harsh environment in China. It is also found that the material used for making connectors was not fitted to the standard.
{"title":"Failure analysis on bolt-type power connector's application","authors":"Guoping Luo, Jian-guo Lu, Ji-gao Zhang","doi":"10.1109/HOLM.1999.795930","DOIUrl":"https://doi.org/10.1109/HOLM.1999.795930","url":null,"abstract":"Bolt-type power connectors are widely used in China due to their simple structure and low cost. However, investigation shows that this kind of power connectors needs continuous maintenance and frequent replacement. By analyzing the failed connectors that were collected from different cities and sites, high connection resistance of most samples was found. Clearly high temperature has been occurred at each connector. Bolts of nearly 45% of the testing connectors appeared loosening, which caused low contact pressure, evidently the bolts were stress relaxed. Even the bolts were rusted and locked, the strand wires could still rock in the grooves of the connectors. Sliding and fretting tracks were clearly observed and appeared different kinds of morphologies. Serious contaminants and corrosive film covered on the groove surfaces, which caused high temperature rise and further enhanced stress relaxation. Surfaces of almost 58% samples preserved obvious melting or welding appearance, some of them were even burnt out, evidently there were gaps between wires and connector. Therefore, the structure of the bolt type power connectors can hardly stand for the harsh environment in China. It is also found that the material used for making connectors was not fitted to the standard.","PeriodicalId":299141,"journal":{"name":"Electrical Contacts - 1999. Proceedings of the Forty-Fifth IEEE Holm Conference on Electrical Contacts (Cat. No.99CB36343)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129938970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1999.795949
N. Aukland, H. Hardee, A. Wehr-Aukland, P. Lees
Fretting experiments were conducted on two different material systems at elevated temperatures. One of the material systems was a clad material. The clad material was 120 micro-inches thick of an alloy consisting of 65% gold, 21% palladium, 14% silver over an 800 micro-inch nickel sublayer. The other material system was 40 micro-inches of electroplated soft gold over 80 micro-inches of palladium over 80 micro-inches of nickel sublayer. Four different temperature levels were used during this research project. The different temperature levels were 20, 50, 100 and 200/spl deg/ C. Normal force was set at 200 grams. Fret amplitude was 50 microns. The fretting frequency was 8 Hz. Some limited fretting experiments were conducted using a new contact lubricant (CLT: X-10). Contact resistance data were collected on the number of cycles to reach specific contact resistance levels. These levels were 10, 50, 100 and 250 milliohms. A four wire milliohmmeter, specifically designed to collect contact resistance values, was used to collect the data. A material study was conducted as part of this project. The two different material systems were compared using a simple t-test, based on the number of fretting cycles to exceed 0.25 ohm. At room temperature, the clad material lasted 10 times longer than the gold over palladium material system. At 50 and 100/spl deg/C the clad material was still better than the gold over palladium material system, but the overall improvement in fretting performance had decreased. At 50/spl deg/C, the clad material lasted 3.2 times longer than the electroplated gold over palladium. The improvement in fretting performance by the clad material at 100/spl deg/C was slightly better and the clad material lasted 5.8 times longer than the gold over palladium material. At 200/spl deg/ C the clad material was only slightly better than the gold over palladium material system. If the number of cycles to failure at 20/spl deg/C is compared to the number of cycles to failure at 200/spl deg/C for both material systems, the increase in temperature caused a decrease in fretting performance. The average cycles to failure at 20/spl deg/C for the clad material was 1,600,000 cycles. At 200/spl deg/C, the clad material lasted for 72,000 cycles. The electroplated gold over palladium material system lasted for an average of 189,000 cycles at 20/spl deg/C and 64,600 cycles at 200/spl deg/C. In general, over the entire temperature range, the clad material was a much better contact material.
{"title":"A comparison of a clad material (65Au21Pd14Ag) and an electroplated gold over palladium material system under fretting conditions at elevated temperatures","authors":"N. Aukland, H. Hardee, A. Wehr-Aukland, P. Lees","doi":"10.1109/HOLM.1999.795949","DOIUrl":"https://doi.org/10.1109/HOLM.1999.795949","url":null,"abstract":"Fretting experiments were conducted on two different material systems at elevated temperatures. One of the material systems was a clad material. The clad material was 120 micro-inches thick of an alloy consisting of 65% gold, 21% palladium, 14% silver over an 800 micro-inch nickel sublayer. The other material system was 40 micro-inches of electroplated soft gold over 80 micro-inches of palladium over 80 micro-inches of nickel sublayer. Four different temperature levels were used during this research project. The different temperature levels were 20, 50, 100 and 200/spl deg/ C. Normal force was set at 200 grams. Fret amplitude was 50 microns. The fretting frequency was 8 Hz. Some limited fretting experiments were conducted using a new contact lubricant (CLT: X-10). Contact resistance data were collected on the number of cycles to reach specific contact resistance levels. These levels were 10, 50, 100 and 250 milliohms. A four wire milliohmmeter, specifically designed to collect contact resistance values, was used to collect the data. A material study was conducted as part of this project. The two different material systems were compared using a simple t-test, based on the number of fretting cycles to exceed 0.25 ohm. At room temperature, the clad material lasted 10 times longer than the gold over palladium material system. At 50 and 100/spl deg/C the clad material was still better than the gold over palladium material system, but the overall improvement in fretting performance had decreased. At 50/spl deg/C, the clad material lasted 3.2 times longer than the electroplated gold over palladium. The improvement in fretting performance by the clad material at 100/spl deg/C was slightly better and the clad material lasted 5.8 times longer than the gold over palladium material. At 200/spl deg/ C the clad material was only slightly better than the gold over palladium material system. If the number of cycles to failure at 20/spl deg/C is compared to the number of cycles to failure at 200/spl deg/C for both material systems, the increase in temperature caused a decrease in fretting performance. The average cycles to failure at 20/spl deg/C for the clad material was 1,600,000 cycles. At 200/spl deg/C, the clad material lasted for 72,000 cycles. The electroplated gold over palladium material system lasted for an average of 189,000 cycles at 20/spl deg/C and 64,600 cycles at 200/spl deg/C. In general, over the entire temperature range, the clad material was a much better contact material.","PeriodicalId":299141,"journal":{"name":"Electrical Contacts - 1999. Proceedings of the Forty-Fifth IEEE Holm Conference on Electrical Contacts (Cat. No.99CB36343)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129113944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1999.795926
N. Minoura, T. Soma, K. Sawa
The purpose of this work is to make clear the phenomena of electrical contacts in liquid environments with light-duty application. The automotive electronic fuel pump is operated by a small D.C. motor and its commutation arc is carried out in gasoline. A commutation arc can be regarded as a kind of breaking arc. Therefore we projected the application of a commutation arc in gasoline to electrical contacts. The break operation studies have been conducted on Ag and Pd materials under the inductive condition in three different dielectric liquids (distilled water, methanol and n-hexane). The characteristics of the contact resistance and material transfer are strongly affected by dielectric liquids. According to our research, judging from material wear and contact resistance, there is the possibility that better contact reliability can be attained in n-hexane with a low load current. This is because in n-hexane there is very little wear and flat erosion can be achieved, due to the film on the contact surface made of carbon that is contained in n-hexane. But the contact resistance occasionally becomes high and unstable with a high load current. Thus, this paper mainly reports the results of the detailed experiment about erosion and contact resistance in n-hexane.
{"title":"The effect of erosion and contact resistance of electrical contacts in n-hexane on contact reliability","authors":"N. Minoura, T. Soma, K. Sawa","doi":"10.1109/HOLM.1999.795926","DOIUrl":"https://doi.org/10.1109/HOLM.1999.795926","url":null,"abstract":"The purpose of this work is to make clear the phenomena of electrical contacts in liquid environments with light-duty application. The automotive electronic fuel pump is operated by a small D.C. motor and its commutation arc is carried out in gasoline. A commutation arc can be regarded as a kind of breaking arc. Therefore we projected the application of a commutation arc in gasoline to electrical contacts. The break operation studies have been conducted on Ag and Pd materials under the inductive condition in three different dielectric liquids (distilled water, methanol and n-hexane). The characteristics of the contact resistance and material transfer are strongly affected by dielectric liquids. According to our research, judging from material wear and contact resistance, there is the possibility that better contact reliability can be attained in n-hexane with a low load current. This is because in n-hexane there is very little wear and flat erosion can be achieved, due to the film on the contact surface made of carbon that is contained in n-hexane. But the contact resistance occasionally becomes high and unstable with a high load current. Thus, this paper mainly reports the results of the detailed experiment about erosion and contact resistance in n-hexane.","PeriodicalId":299141,"journal":{"name":"Electrical Contacts - 1999. Proceedings of the Forty-Fifth IEEE Holm Conference on Electrical Contacts (Cat. No.99CB36343)","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117214585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
When silicone vapor which adsorbed on contact surfaces is subjected to high temperature due to electric discharge in the atmosphere, SiO/sub 2/ is formed by chemical decomposition of the adsorbed silicone molecular. When SiO/sub 2/ is formed on contact surfaces and is caught in the interface of contacts, contact failure is caused by an insulation property of SiO/sub 2/. Newly developed contact material of Ag(40wt%)-Pd(60wt%) alloy with a small amount dopant of Mg was applied experimentally to a micro relay. This material shows remarkable improvement of contact resistance property for contaminant oxide film in comparison with usual Ag-Pd contacts. In this study, the contact resistance property for the number of make-break switching operations of the Ag-Pd-Mg alloy was examined by wide range electrical conditions under saturated (1300 ppm) silicone vapor. Obtained contact resistance properties were compared with the Ag-Pd alloy itself and Ag-Pd overlaid with Au(90wt%)-Ag(10wt%) which is used usually. As results, prolonged low contact resistance property of the Ag-Pd-Mg alloy for silicone environment was found. The mechanism of the low contact resistance property was clarified by cleaning effect based on removal of powder products formed from the contact traces.
{"title":"Effect of Mg doping on increase in the life with low contact resistance of Ag-Pd alloy switching contacts in silicone vapor environments","authors":"T. Tamai, A. Sato, S. Ito","doi":"10.1109/6144.846759","DOIUrl":"https://doi.org/10.1109/6144.846759","url":null,"abstract":"When silicone vapor which adsorbed on contact surfaces is subjected to high temperature due to electric discharge in the atmosphere, SiO/sub 2/ is formed by chemical decomposition of the adsorbed silicone molecular. When SiO/sub 2/ is formed on contact surfaces and is caught in the interface of contacts, contact failure is caused by an insulation property of SiO/sub 2/. Newly developed contact material of Ag(40wt%)-Pd(60wt%) alloy with a small amount dopant of Mg was applied experimentally to a micro relay. This material shows remarkable improvement of contact resistance property for contaminant oxide film in comparison with usual Ag-Pd contacts. In this study, the contact resistance property for the number of make-break switching operations of the Ag-Pd-Mg alloy was examined by wide range electrical conditions under saturated (1300 ppm) silicone vapor. Obtained contact resistance properties were compared with the Ag-Pd alloy itself and Ag-Pd overlaid with Au(90wt%)-Ag(10wt%) which is used usually. As results, prolonged low contact resistance property of the Ag-Pd-Mg alloy for silicone environment was found. The mechanism of the low contact resistance property was clarified by cleaning effect based on removal of powder products formed from the contact traces.","PeriodicalId":299141,"journal":{"name":"Electrical Contacts - 1999. Proceedings of the Forty-Fifth IEEE Holm Conference on Electrical Contacts (Cat. No.99CB36343)","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129077382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1999.795928
M. Braunovic
The effect of contact-aid compounds on the stability of aluminum-to-copper connections under different operating and field conditions has been investigated. A number of contact-aid compounds, previously not evaluated, were subjected to parametric, stability and field tests. The contact aids were evaluated and ranked on the basis of their stability to a thermal degradation, spreading tendency, stability to UV radiation and field conditions as well their effect on their effects on the performance of aluminum-to-copper contacts under current-cycling and fretting.
{"title":"Further studies of different contact aid compounds for aluminum-to-copper connections","authors":"M. Braunovic","doi":"10.1109/HOLM.1999.795928","DOIUrl":"https://doi.org/10.1109/HOLM.1999.795928","url":null,"abstract":"The effect of contact-aid compounds on the stability of aluminum-to-copper connections under different operating and field conditions has been investigated. A number of contact-aid compounds, previously not evaluated, were subjected to parametric, stability and field tests. The contact aids were evaluated and ranked on the basis of their stability to a thermal degradation, spreading tendency, stability to UV radiation and field conditions as well their effect on their effects on the performance of aluminum-to-copper contacts under current-cycling and fretting.","PeriodicalId":299141,"journal":{"name":"Electrical Contacts - 1999. Proceedings of the Forty-Fifth IEEE Holm Conference on Electrical Contacts (Cat. No.99CB36343)","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126403781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1999.795920
Z. Chen, G. Witter
Mechanical parameters were correlated with dynamic contact welding for a hard silver contact alloy. The study was conducted with a model switch that simulated an automotive relay. The switching tests conducted at 13 VDC for rigid and flexible blades correlated contact bounce to weld strength. The weld strength was shown to be highest for single bounces of very short duration and contact gap. Flexible contact springs were shown to create weak welds by mechanical adhesion.
{"title":"Dynamic welding of silver contacts under different mechanical bounce conditions","authors":"Z. Chen, G. Witter","doi":"10.1109/HOLM.1999.795920","DOIUrl":"https://doi.org/10.1109/HOLM.1999.795920","url":null,"abstract":"Mechanical parameters were correlated with dynamic contact welding for a hard silver contact alloy. The study was conducted with a model switch that simulated an automotive relay. The switching tests conducted at 13 VDC for rigid and flexible blades correlated contact bounce to weld strength. The weld strength was shown to be highest for single bounces of very short duration and contact gap. Flexible contact springs were shown to create weak welds by mechanical adhesion.","PeriodicalId":299141,"journal":{"name":"Electrical Contacts - 1999. Proceedings of the Forty-Fifth IEEE Holm Conference on Electrical Contacts (Cat. No.99CB36343)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122324995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1999.795934
V. Behrens, T. Honig, A. Kraus
By means of a single phase vacuum model switch with a current range from 50 A (for current chopping) to 1500 A (for AC4 contact erosion) contact materials of the group of tungsten carbide/silver, tungsten carbide/copper and tungsten/copper are evaluated. The properties focused on are current chopping in new state as well as during service life, contact erosion due to AC4 life due to cracking and reignition behavior. It is found that in regard to current chopping best results are obtained with WC/Ag and WC/Cu, while W/Cu and even an optimized W/Cu having antimony additives show substantially higher chopping currents. In regard to AC4 life and especially to reignitions the copper containing materials were found to be superior to the silver containing materials. In the case of WC/Cu there are indications of poor contact resistance during service life which is attributed to the evaporation of the copper from the arc treated area in combination with a poor wetting behavior of the molten copper to the WC particles.
{"title":"Tungsten and tungsten carbide based contact materials used in low voltage vacuum contactors","authors":"V. Behrens, T. Honig, A. Kraus","doi":"10.1109/HOLM.1999.795934","DOIUrl":"https://doi.org/10.1109/HOLM.1999.795934","url":null,"abstract":"By means of a single phase vacuum model switch with a current range from 50 A (for current chopping) to 1500 A (for AC4 contact erosion) contact materials of the group of tungsten carbide/silver, tungsten carbide/copper and tungsten/copper are evaluated. The properties focused on are current chopping in new state as well as during service life, contact erosion due to AC4 life due to cracking and reignition behavior. It is found that in regard to current chopping best results are obtained with WC/Ag and WC/Cu, while W/Cu and even an optimized W/Cu having antimony additives show substantially higher chopping currents. In regard to AC4 life and especially to reignitions the copper containing materials were found to be superior to the silver containing materials. In the case of WC/Cu there are indications of poor contact resistance during service life which is attributed to the evaporation of the copper from the arc treated area in combination with a poor wetting behavior of the molten copper to the WC particles.","PeriodicalId":299141,"journal":{"name":"Electrical Contacts - 1999. Proceedings of the Forty-Fifth IEEE Holm Conference on Electrical Contacts (Cat. No.99CB36343)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116504245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.1109/HOLM.1999.795947
F. Hubner-Obenland, J. Minuth
It is well known that the resistance of a wearing contact may rise from less than a milliohm to more than a kiloohm within months or maybe in less than a microsecond. The automobile industry has considerable trouble with short-term intermittences of contacts under vibration stress. The vibration of the vehicle can be simulated quite well with a shaker. Measuring the long-term increase of the resistance can be done by switching off the shaker from time to time. But the electromagnetic field of the shaker prevents the measurement of the resistance-changes with standard equipment while the shaker is working. A test equipment and a test method have been developed that make it possible to measure contact resistances in real-time and over a resistance-range of six decades. As this can be done while the shaker is running, intermittences not only can be detected but also measured. This equipment can be used for finding out whether a certain contact system can be used for a concrete application. Also it assists the research work on the mechanisms of contact intermittences. A set of contacts has been tested and their electrical behaviour has been compared with the status of their contact surface.
{"title":"A new test equipment for high dynamic real-time measuring of contact resistances","authors":"F. Hubner-Obenland, J. Minuth","doi":"10.1109/HOLM.1999.795947","DOIUrl":"https://doi.org/10.1109/HOLM.1999.795947","url":null,"abstract":"It is well known that the resistance of a wearing contact may rise from less than a milliohm to more than a kiloohm within months or maybe in less than a microsecond. The automobile industry has considerable trouble with short-term intermittences of contacts under vibration stress. The vibration of the vehicle can be simulated quite well with a shaker. Measuring the long-term increase of the resistance can be done by switching off the shaker from time to time. But the electromagnetic field of the shaker prevents the measurement of the resistance-changes with standard equipment while the shaker is working. A test equipment and a test method have been developed that make it possible to measure contact resistances in real-time and over a resistance-range of six decades. As this can be done while the shaker is running, intermittences not only can be detected but also measured. This equipment can be used for finding out whether a certain contact system can be used for a concrete application. Also it assists the research work on the mechanisms of contact intermittences. A set of contacts has been tested and their electrical behaviour has been compared with the status of their contact surface.","PeriodicalId":299141,"journal":{"name":"Electrical Contacts - 1999. Proceedings of the Forty-Fifth IEEE Holm Conference on Electrical Contacts (Cat. No.99CB36343)","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122456429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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