NEW GENERAL PURPOSE RELAY 



1039 



STATIONARY WIRE ASSEMBLIF 



TWIN WIRE ASSEMBLIES 



Fig. 12 — Molded stationary and twin wire a>ssenil)li(!s, before cutting to length. 



the ends of the twin wires, cov^er anchorage, damping matei'ial sup- 

 port, etc. 



7. CONTACTS AND CONTACT WELDING 



Since the primary piupose of the relay is to open and close electrical 

 circuits through the contacts, there has been a special effort to make 

 these contacts as reliable as possible. Accordingly, palladiimi is used for 

 all contact surfaces. This use of precious metal substantially eliminates 

 opens due to corrosion. Palladium not only gives outstanding reliability 

 but studies indicate that its use results in the best economic balance be- 

 tween manufacturing cost and service because of the reduced main- 

 tenance expense. 



Open circuits due to particles of dirt between the contact surfaces are 

 largely eliminated by the use of a contact cover, complete independence 

 of the twin contacts described in the section Relay Performance, and 

 the dynamic characteristics of the wire springs. However, to further 

 reduce the incidence of dirt troubles, the surfaces of the twin contacts 

 are coined to a cylindrical shape. This greatly reduces the effective bear- 

 ing area between the twin contacts and the flat surfaces of the single 

 contacts. Thus, even if an occasional dirt particle should come to rest 

 on one of the contact surfaces, there is small likelihood that it would 

 be in the contact area. 



Since welding contacts to wires instead of flat springs is relatively 

 new, considerable attention was given to the dcxclopment of suitable 



