An optimization of electrical contacts design in fluorescent lighting switches

With the constantly increasing use of fluorescent lighting, more and more important and irreversible weldings of contacts occur inside low voltage electric apparatus and in particular inside switches. The aim of this study is to understand and avoid this phenomena. We used an "experiment design" upon the Taguchi method to quantify the influence of the following factors: composition of contact materials, curvature radius of contact parts, assembly method of contact parts on support, contact force. Each of the above factors was considered at three different values which enabled us to apply the study to a L9 matrix. The influence of each factor was estimated with the following criteria applied to the contacts tested: number of weldings, erosion loss and temperature rise. The tests are completed with bounce duration and arc energy measurements. Electrical tests were made according to testing conditions of standard CEI 669-1 with a R-L-C load at 230 V, 10 A. The microcomputer driven mechanical testing equipment is described. Results show that the contact force is the most influent parameter and that the asymmetrical combination of AgNi as fixed contact and AgSnO/sub 2/ as movable contact will cause the lowest number of weldings.