The numerical evaluation study for the relationship between contact-sticking and transferred pip on electrical contacts mounted on relays in DC 42V automobile circuit

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The growing process of the transferred pips at the make-only contacts or the break-only contacts mounted individually on two relays has been photographed every 100 switching operations from two directions by two digital microscopes. The shape of transferred pips piled up at the surfaces of contacts on the tips of two cantilever supporting arms arranged parallel is not conical, and becomes the sphinx image type with the magnification of the height of transferred pip. This formation process of pip which resembles the sphinx image is considered that the evaporated atoms and scattered particles in the arc column are piled up at the top side of the parallel supporting arms, because the arc column of each arc discharge is extruded by the Ampere force for the arc current carried through these arms. Moreover, we think that when the pip greatly grew, the contact surfaces at make-only operation are melted partially and these surfaces were welded at the static contact period, because the appearan … More ce of the arc discharge and the molten bridge just before making contacts and in the rebound period are confirmed from the voltage waveform.With respect to measurement of shapes of transferred pips and eroded craters, a scanning laser microscope was used to per-form 3-D image observation as well as numerical evaluation (measurements of depth, height, diameter, and volume calculation) of the transferred pips and eroded craters formed on the electrodes. Especially, for the volume measurement, new algorithms called "Trapezoidal Approximation Algorithm" and "Divided Trapezoidal Approximation Algorithm", respectively, were developed. Moreover, in order to make comparisons of shapes of pips and eroded craters formed for different contact materials and/or under different load conditions, drawing a graph by employing the pip height or crater depth values as the vertical axis and their diameters as the horizontal axis has been confirmed to be useful.Using the low-speed and constant-speed separating equipment, the figures of breaking arc were photographed in the lms interval. it is found that the fluctuating range of the location in arc bright spots was big in the initial stage of breaking arc discharge and in the big fluctuating part of arc voltage waveform, and on the other hand that the fluctuating range of the location of arc bright spots was narrow in the later stage of breaking arc discharge.In Home page http://www.ipc.shizuoka.ac.jp/~tjsekik/, the following were reported "Moving pictures of growing process of the transferred pips and the motion situation of cathode spot and anode spot of breaking arc discharge". Less