Some characteristics of AgPd40/60 contacts mounted on miniature relays that make and break a dc 30 v‐10 a resistive circuit

Abstract

While the AgPd40/60 electrical contacts mounted on the miniature relays continued to make and break a dc 30 V‐10 A resistive circuit for 100,000 times, on every switching operation the number of bounce, the duration of closing are, the contact resistance, the temperature on the stationary contact arm, and the duration of opening are were measured and recorded. In this paper, these measured values are shown in many figures and compared with data on Ag, Pd, AgCdO12 wt percent and AgSn2 9.3 wt percent. Furthermore, the values measured on some switching operations before and after the contact pairs adhered are listed in the tables. The variation of the closing are duration has the same tendency as the increase and decrease of the number of contact bounce. Also, the contact resistance becomes low after the closing operation in which the duration of the closing are is long. However, the average duration of the closing are was about half that in Pd pairs and was the same degree in Ag and AgSn2 9.3 wt percent contacts. Although the duration of the opening are was double that in Pd contacts, it was not especially long compared with that in Ag, AgCd0 12 wt percent and AgSnO2 9.3 wt percent contacts. However, the pip made of transferred metal on the anode surface would grow largely rather than be scattered by subsequent switching arcs. This largely grown pip causes contact sticking, as in the case of Pd contacts. Although black polymer is observed on two contact surfaces, the top of a large pip on the anode and the bottom of an eroded crater on the cathode are whitish metallic surfaces with microroughness. Thus, the contact resistance at current of dc 10 A was unchanged for 100,000 switching operations. However, the average contact resistance was higher than that of Ag and Pd contacts measured under the same experimental condition.