An investigation into the British Standard sulphur dioxide test for contacts and connections

Summary

A study has been made of the British Standard Sulphur Dioxide Test for Contacts and Connections. BS2011: Part 2.1 Kc. The most important test parameters were determined by measuring the corrosion rate of copper and nickel samples under different operating conditions of the equipment, relative humidity being found the most important. The causes of variable results obtained with the test are discussed and recommendations for achieving reproducible operation are made The test atmosphere was analysed by mass spectrometric and titrimetric techniques in order to identify the species most active in promoting corrosion, and proved to be complex, containing sulphur, carbon and nitrogen oxides. Test atmospheres produced by combustion were observed to be much more corrosive than cylinder-generated test atmospheres. The origin of this difference was shown to be the presence of small concentrations of nitrogen oxides in the former. Suggestions for altering the test specification are made.

Additional information

Notes on contributors

E. Knight

E. Knight is a member of the Materials Physics Department at Standard Telecommunication Laboratories (STL) Harlow. He joined the Materials and Components Division at STL in 1966 after graduating from Brunei University with a degree in Metallurgy After studying the epitaxy of evaporated thin films of noble metals by transmission electron microscopy, he joined the Electrical Contacts Group He is a member of the Institution of Metallurgists and serves on BSI and IEC committees in addition to Metal Finishing and Standards Working Groups within STL and ITT.