Activation of Electrical Contacts 

 by Organic Vapors 



By L. H. GERMER and J. L. SMITH 



Unrcproducibiliti) of earlier work on the erosion of relay contacts has been 

 traced to the effects of organic vapors in the atmosphere. Carbon from de- 

 composition of these vapors greatly alters the conditions under which an 

 electric arc can be initiated and can be sustained. The importance from the 

 standpoint of erosion comes from the fact that for many circuit conditions 

 contacts activated by this carbon cannot be protected against severe arcing 

 by any conventional capacitance-resistance network. This paper reports 

 investigations which have enabled us to understand the activation of contacts 

 by organic vapors. 



TABLE OF CONTENTS 

 Introduction 770 



Part I. Electrical Effects 772 



1. Observations on Activation 772 



1.1 Striking Field 774 



1 .2 Arc Voltage 775 



1 .3 Minimum Arc Current 777 



1 .4 Erosion 778 



1.4(a) Palladium and Platinum 778 



1.4(b) Silver and Gold 779 



2. Interpretation of Activation 780 



2.1 Striking Field 781 



2.2 Arc Voltage 784 



2.3 Minimum Arc Current 785 



2.4 Erosion 786 



2.4(a) Palladium and Platinum 786 



2.4(b) Silver and Gold 788 



2.4(c) Anode Arcs and Cathode Arcs 790 



3. Recapitulation 794 



Part II. Activating Carbon 796 



4. Composition of Activating Powder and Rate of Production 796 



4.1 Composition 796 



4.2 Rate of Production 797 



5. Surface Adsorption 798 



5.1 Benzene ^lolecules on Contact Surfaces 798 



5.2 Inhibiting Surface Films 801 



5.3 Alloys 802 



769 



