A study of effects of silicate thickened lubricants on the performance of electrical contacts

Silicon contamination has been noted for several years as a significant problem in electrical contacts. Both silicon compounds and silicone have been studied. In this paper a source of mineral silicon has been identified in the lubricant thickening agent. Clay based thickening agents have been used with relative success in low cost switches for applications up to 50 amps in circuits with less than 16 volts with resistive and inductive reactances. Typically the switches are the sliding type composed of base metal or coated base metal contacts used to interrupt current flow. The impetus for using this thickener is high thermal stability and low cost. The failures, however, that occur in practice do not exhibit themselves in standard testing. Areas investigated in this paper include contact wiping and arcing effects. Standard contact fundamentals were employed to explain the effects caused by the lubricant.