Remreed Switching Networks for No. 1 and No. 1A ESS: Remreed Contact and Switching Network Evaluation

During t h e development of new switching hardware, m a n y evaluations and tests are performed. The broad objectives of these tasks are to prove and assure t h a t t h e performance and reliability of the new equipment will meet Bell System needs. High on t h e priority list of objectives are (i) a reliable method of manufacture, (ii) an in-service life of 40 years, and (Hi) maintenance-free performance during operation. This paper summarizes the work conducted at Bell Laboratories on t h e remreed contact, switch, grid, and frame design to meet these objectives. To show t h a t the broad objectives could be met by the remreed design, several specific goals had to be achieved. T h e y are: (i) T h e adequacy of the new hard-gold contact surface had to be established. T h e ferreed sealed contact, predecessor to the remreed sealed contact, has a diffused gold-silver plated contact surface. 663 (w) The ruggedness of the sealed contact in the new switch package had to be established to assure t h a t high initial failure rates, induced by handling and shipping, did not occur. (Hi) The point where the failure rate of the sealed contact begins to increase, i.e., where the contact begins to wear out, had to be determined. At this point, a mechanism of contact erosion from small arc discharges leads to the high-resistance failure mode. The design goal regarding this failure mode was to produce contact surfaces t h a t exhibited failure rates the same as or lower than the failure rates of the ferreed contact.