Investigation on Contact Resistance Behavior of Switching Contacts Using a Newly Developed Model Switch

In order to investigate the long-term behavior of contact resistance in low-voltage contactors under the influence of electric arcs in polymer housings, a new model switch was developed. The model switch permits the modification of different factors such as contact gap, contact force, closing and/or separation speed of the contacts, and arc-chamber materials among others. Several experimental series using Ag/Ni10 contacts were carried out as a reference. The contact resistance was determined using two different measurement current sources. Contact resistance data were analyzed using Weibull functions as well as nonparametric statistics. Information regarding surface structures, their chemical composition, and formed crystalline phases of contact and ambient materials on the contact surfaces was obtained through several material analysis methods. This paper presents the main characteristics of the model switch and some experimental results about contact resistance behavior under the influence of ac-arcs in outgassing polymer surroundings.