ASTM B576-94 pdf free.Standard Guide for Arc Erosion Testing of Electrical Contact Materials.
This guide covers the major variables which affect therate of arc erosion of electrical contact materials and serves asa guide in developing more detailed specifications for arcerosion tests.This standard does not purport to address all of thesafety concerns，if any, associated with its use. lt is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.
Arc erosion testing involves some vaporization of ma-terial. It is the responsibility of the user to become familiarwith all hazards including those identified in the appropriateMaterial Safety Data Sheet for the material being tested.2.Significance and Use
The significance of the variables set forth in this guidewas proved by various laboratories using several test systemsat test currents ranging from 100 to 35 000 A. These variableswill be significant for any case where voltage and current aresufficient to produce arcing.The area, shape, and thickness of the contact affect theerosion rates. As an example of shape effects, the radius of thespherical crown affects the erosion in at least two ways: ( l) itchanges the effective diameter of the contact and, ( 2) it affectsthe manner in which the arc moves about on the surface of thecontact. A contact with a hemispherical crown presents nosharp edges that would result in different amounts of erosionproducts for a given amount of arcing and aids in the control ofthe arc when operating in air and other gases.The contacts may be given a type of normal shape andsurface roughness by a number of arcing operations prior torecording the contact loss.There may be a difference in theeffect of shape and diameter for different environments.
Contact mounting, attachment, and bond integrity canaffect the arc erosion of materials and should be specified.Contact Velocity and Maximum Arc The veloc-ity of separation and the maximum arc length affect the erosionrate and, therefore, should be specified in formulating a test.ASTM B576 pdf download.