(Record and Abstract) September 27-28, 2001 Hotel Metropolitan Akita, Akita, Japan Sponsorship: Technical group of Electromechanical devices in Electronics Society of the Institute of electronics, Information and Communication Engineers. Co-sponsored: The Research and Engineering Meeting of Electromechanical Components and Contact Technology, and IEEE Sendai Section. Assent: The Faculty of Engineering and Resource Science of Akita University.
Thursday, September 27, 2001 (Session 1) Chairs: N.Ben Jemaa (University of Rennes1), T.Tamai (Hyogo Univ. of Teacher and Education) 1.EMD 2001-45 [Invited Paper] A Review of Volumetric Erosion Studies in Low Voltage Electrical Contacts John W. McBride (University of Southampton)
| This paper presents a review of volumetric erosion studies applied to electrical contacts. The numerical methods presented are generic and could equally be applied to a number of areas where surfaces have been eroded or damaged. Equally there is no scale limitation of the surfaces to which the numerical methods can be applied. The papers starts with a general introduction of the issues associated with the measurement of contact erosion, and then presents a summary of various hardware system for making 3D measurements of surfaces such as electrical contacts. This is followed by a review of the generic form fitting methods and also volume calculation methods. The paper concludes with a review of results taken from a test system for contact studies and from contact samples taken from commercial relays. |
| Ag, Ag/SnO2 12wt%, Ag/CdO 12wt% contacts mounted on a small electromagnetic relay are tested in a DC30V-10A resistive circuit as the make-only-contacts and the break-only-contacts. In this experience, we measure some electrical characteristics and observe a transferred pip on the cathode of make-only-contacts. The pip of Ag/CdO 12wt% contacts continue to grow up without collapse and the sticking occurs only at the Ag/CdO 12wt% contacts. We expect that the possibility of the sticking increase when the pip grows higher than the half of the contact gap. The Ag/SnO2 12wt% contacts don't stick, because a pip collapses several times. We think the collapse of large pip prevents sticking. |
| Ag, Pd, and Cu contacts were operated in air and nitrogen atmosphere to break an inductive DC load current of 0.5 to 3 A. Ag contacts in air and nitrogen, as well as Pd contacts in air, showed the anode-gain and cathode-loss characteristics. Pd contacts in nitrogen were likely to show the pip-formation on cathodes and the crater-formation on anodes. For Cu contacts, differences of the resultant anode profiles were observed between the air samples and the nitrogen samples. Moreover, the pip/crater volumes measured with a scanning laser microscope showed some different tendencies as compared to the mass change characteristics. |
| Spectral intensity of breaking arc is measured to research arc temperature. Arc temperature is determined by Boltzmann plot of measured date. Arc temperature immediately after ignition are about 7000K for Cu and about 5000K for Ni. Just after arc extinction, its temperature was about 4500K for Cu and about 4000K for Ni respectively, even if the experimental conditions are changed. Arc duration and spectral intensity depend on interrupted electric power. After thirty breaking arcs, contact surfaces erode and cathode erosion is larger than anode erosion. |
| In the automobile industry, switches are powered actually at 14V and 42 in the future. The current level can be as low as minimum current for signal switches and as high as few ten amperes for power relay. In low current range and for all contact materials tested (Ag, Cu, Pd, Au, Sn, Ni), short arc duration values versus current are grouped around exponential curves corresponding to multi-burst arc model. At medium current level, the long arc duration observed in is largely extended and it follows linear relationship of arc duration. It has been found that up to 10 A the material has no significant effect on arc duration Beyond this limit some materials (primarily AgSnO2) induce high arc durations and large extinction gap. In addition high-speed separation reduce arc duration whereas it increase the extinction in inductive load and diminish in resistive loads. The subsequent material transfer, from the anode to the anode, for short arc duration and length and in the reverse direction when arc is lengthened to 1mm. Up this limit both, anode and the cathode loose material by droplet ejection mechanism. Finally AgSnO2, which is claimed as a best compromise at 14 V for all loads, cannot be used at 42 V for two reasons. It exhibits high erosion and requires a larger contact gap to ensure a successful break. |
| Our study aims to investigate the degradations of the contact material under arcing, in automotive power relays and switches. In this article we will present our results on the problem of the increase of the contact resistance after arcing, at 14VDC and 30-40A. We have seen that the contact resistance is much larger in an inductive circuit (up to 6mW) than for a resistive circuit (below 1mW ) with differences between the materials. This increase in the resistance in an inductive circuit is attributed to the deposit of pollution based on silver oxide and carbon based elements on the surface of the contacts (black powder) when the arc exceeds 200 µm or 2 ms and enters the gas phase. |
| The surface film of slip-ring is important for sliding contact phenomena. The surface film is changed by atmospheric temperature, humidity and air pressure. A main purpose of our study is to examine the effect of oxygen gas on the sliding contact phenomena. In the present experiment, we examined the contact voltage drop for continuous sliding when the atmosphere is changed from the low pressure to atmosphere pressure by introducing oxygen (O2 20%+N2 80%) or nitrogen gas. As a result, the contact voltage drop increase rapidly with increasing gas pressure, and its fluctuation also becomes large. These phenomena are observed in both cases of oxygen (O2 20%+N2 80%) and nitrogen for introducing gasses. The results clearly show that the sudden increase of contact voltage drop is affected by the other factors except for oxide film. Actually, the oxide film is not formed in the nitrogen atmosphere. Furthermore, the coefficient of friction of carbon and copper ring is changed for ambient atmosphere. It is inferred from these data that the contact voltage drop may be affected by coefficient of friction. When the gas pressure decreases again, the contact voltage drop does not suffer from the effect of ambient gas. Therefore, the contact voltage drop only due to the film resistance seems to be predominant. |
| V-I characteristics of breaking arcs between electric contacts are investigated at several contact materials (Au, Ag, Cu, Pt, Ni). The time variations of arc voltage, arc current and gap length are measured, simultaneously. V-I characteristics and minimum arc voltages were obtained from those measured values. The result shows that minimum arc voltages for each contact material agreed with those values by Holm. The V-I characteristics at several contact materials (Au, Ag, Cu, Pt) except Ni electric contacts almost agreed with Holm's V-I characteristics. The difference for V-I characteristics between Ni electric contacts and the others is because of the low electric field of the arc column for nickel electric contacts. |
| The digital micromirror device (DMD) is a new display device fabricated by the micro machining technique and used in projectors. In this paper, the DMD serves as an ultraviolet exposure system and is tested in applications for projection exposure systems and rapid prototyping. In the system, the DMD and a mercury lamp are used as a pattern generator and an UV source, respectively. Since the developed exposure system doesn't need a mask or LASER, a simple and low cost system can be realized. |
| A LiNbO3 piezoelectric actuator controls the contact gap. Its control accuracy is sub-micron. The voltage, the current, and the displacement of the contact were measured. The electrical discharge phenomenon and the bridge phenomenon of the contact were analyzed from the measurement data. In addition, the contact load was presumed from the measurement data. Continuous data vs. time were statistically analyzed with a computer. For the electrical discharge phenomena, the generation probability, the discharge time, and the discharge distance were derived. The length of the bridge and the bridge resistance were derived for the bridge phenomenon. |
| The effects of thin Ti, Pt and Ti/Pt intermediate layers were studied by TEM on the microstructure of double layered perpendicular magnetic recording media. If no intermediate layer was applied, heteroepitaxial growth and large (20-40nm) grain size of Co-Cr-Nb-Pt recording layer was found on the (111) permalloy backlayer. Introduction of a Ti intermediate layer resulted in the formation of an amorphous phase at the permalloy-Ti interface caused by a chemical reaction with the backlayer and the grain size of Co-Cr-Nb-Pt recording layer was reduced to 10-13nm with no preferred orientation. Pt intermediate layer provided (0001) texture of CoCrNbPt, and 20-40nm grain size. TEM showed high stress field at the permalloy-Pt-CoCrNbPt interfaces, which is supposed to be the reason for increased coercivity by stress induced anisotropy. The best properties were achieved by Ti/Pt stacked intermediate layer: Ti (5nm) interrupted heteroepitaxy, provided high nucleation density and reduced grain size of the Pt (10-16nm) of preferred (111) orientation. The latter conditions provided cph (0001) structure, small (10-16nm) grain size and increased coercivity of the CoCrNbPt recording media. |
| From the environmental point of view, low power consumption and low noise have been required in recent years and new soft switch-mode power supply which has been developed to meet these two requirements will be presented in this paper. The noise level of this new switch-mode power supply is lower than Class-B of CISPR by 30dB or more and the leakage current which tends to be increased in a low-noise power supply can be suppressed to 0.18mA or less to improve the efficiency about by 5%, compared with conventional power supply. This paper will report the operating principle of the SMZ system, operational analysis, oscillating frequency characteristics, efficiency characteristics, noise data etc, and also will describe the mechanism how the noise produced. |
| As new materials, Ag coated fabrics with five different texture are compared by measuring the shielding effect for electromagnetic noise. Each plain fabric sheet is put near a PCB, and magnetic near-field is measured by a shielded-loop probe. As a result, a resonance at the same frequency is observed in the case when the size of all fabrics is same, and the resonance frequency is shifted by changing the size of the sheet. Depending the texture of fabrics, the shielding effect is different. Woven fabric that includes many Ag coated fibers has better shielding effect. |
| The Generic Cabling System for data communication is specified in ISO / IEC 11 801 for premises, which may compromise single or multiple buildings on a campus. This system covers Copper wires and fibre optical cabling. The trend in communication Networking towards higher data rates, increases the performance of structured cabling systems and connectors to meet the requirements of high frequency signal transfer combined with fully shielding and low Crosstalk between signal lines. This technical article describes the cabling and connector Development to satisfy the Category 7, Class F specification, allowing data transfers at signal frequencies up to 600 MHz. |
| Contact materials for control and protection devices must have the following characteristics : low erosion under electric arcing conditions, stable and low electrical resistance so as to limit contact heating, as small welding tendency as possible and low material transfer under DC operating conditions. Various components have been analyzed thermally, their wettability by melted silver studied and laser melting tests have been performed that simulate an electrical arc. We present here several results thus obtained using this method, for doped Ag SnO2 under various conditions on test machines and real systems ( elevator cages and automotive relays ) |
| Many possible applications for Nafion Metal Composite actuators require not one actuator but rather an array of actuators, which we may call a multi-arrayed actuator. We tried to design a multi-array actuator in the membrane itself by simply patterning the surface electrode. We designed several independent octagonal electrodes on the same piece of Nafion. We were able to actuate each actuator independently despite the high constraints and without having activation of the others. We used copper ion as counter ion in the Nafion membrane and a double-layer Platinum electrode. This system yields a large deformation at low voltage. It seems that Copper electrolysis is taking place inside the membrane upon activation. |
| A novel measurement method of displacement using ultrasonic waves having a pair of frequencies (f0 and f1) generated by a piezoelectric device is described. The displacement is estimated from the detected phases of ultrasonic received signals and the detectable displacement range is extended by neighboring the frequency interval (f0-f1). The displacement measurements based on our method were carried out using ultrasonic waves of 5 MHz in water. Although a measurement range using the single frequency measurements is limited to a half of wavelength or less, the extension of the measurement range by 500 times of wavelength is accomplished by our method. |
| Metal foils are expected as substrates for thin film depositions of the wurtzite-type materials to realize novel giant microelectronic devices. Thin films of gallium nitride (GaN), which is one of the wurtzite-type materials and has semiconducting properties, are tried to grow on several kinds of metal foils and their crystallinity is investigated. The crystallinity of GaN thin films is quite poor when they are directly grown on the metal foil surfaces, while highly c-axis oriented GaN thin films are easily obtained on quartz glass substrates at same growth conditions. The crystallinity of GaN thin films grown on the metal foil is drastically improved by inserting silicon dioxide (SiO2) intermediate layers of adequate thickness. On the other hand, aluminum nitride (AlN) and GaN intermediate layers prepared in this work are not effective for the improvements. Causes of the differences and their improvement mechanisms are discussed. |
| The purpose of this work is to compare the operation characteristics using two types of contact with different forms. One has the curved surface electrode that is generally used, the other is notched in the center of the electrode. The advantage of the latter contact may be to make contact force increase. Therefore we can expect to downsize the solenoid coil. Then we investigated the contact resistance, the material wear, and the arc duration. In addition, contact surface was observed by optical microscope to inspect the state of erosion and transfer. According to our research, the contact resistances of both types keep low and stable. The material wear of notched contact is influenced by the made of switching. From the photographs of surface, the behavior of erosion and transfer in two types of contact are different. |
| Bridge-voltages were measured when the contacts were separated slowly below 1mm/s. Cyclic variation of the bridge-voltage waveforms were observed. A periodic variation was observed corresponding to step-like micro-variation of opening speed with 0.5µm. Here, we show some typical bridge-voltage waveforms. |
| For low temperature applications of electrical contacts such as cryogenics, contact resistance performances must be studied in detail. The cryogenical performances of contact resistance are also important in clarifying basic contact mechanisms and controlling the contact resistance. This paper presents low temperature dependencies of the contact resistance of clean surface, contaminated surface, and an evaluation of true contact area based on the breakdown of super conduction. Regarding the constriction resistance as a function of the temperature, it was found that a singular phenomenon of the constriction resistance on the clean surface occurred. For the contaminated surface, the Schottky conduction was observed at oxide film covered contacts. Furthermore, size of the true contact area at very low temperature could be evaluated by the breakdown of the superconduction caused by self magnetic field of the contact current. |