Low current arc characteristics of Au and W-Co reed switch contacts

Arcing phenomena on type-A reed switches are studied. Low current arcs in reed switch contacts are considered. A digital oscilloscope with a sampling frequency of 25 MHz was used to determine the minimum arc current for Au and W-Co plated contacts. The minimum arc current of 0.21 A for Au and 0.62 A for W-Co contacts is established. The maximum temperature in the bridge region is measured versus the contact current, and it is determined that this temperature did not depend on the current in the range between 10 mA and 700 mA. The contact spots after single switching operations are analyzed by a scanning electron microscope. A well-defined difference in surface pattern between the cathodic arc break, the anodic arc break, and the non-arc-break is found.