. The Bell System technical journal . eflection. This recjuires inch contact follow to establisha contact force of 26 grams when the relay is adjusted initially. For thecard lift-off actuated relay where the moving spring had been pre-tensioned to give a contact force of 25 grams initially, after inchwear of the contacts, the contact force will have decreased about 1 is because the stiffness of the moving spring is about gram inch deflection. Card wear does not affect the contact force so longas it is provided for by the width of the slot in the card. 24 ^ CA
. The Bell System technical journal . eflection. This recjuires inch contact follow to establisha contact force of 26 grams when the relay is adjusted initially. For thecard lift-off actuated relay where the moving spring had been pre-tensioned to give a contact force of 25 grams initially, after inchwear of the contacts, the contact force will have decreased about 1 is because the stiffness of the moving spring is about gram inch deflection. Card wear does not affect the contact force so longas it is provided for by the width of the slot in the card. 24 ^ CARD •-■r-l OFF ACIUATION ~ , in 22O - \ I Z 18 - N. \ o 16a. £ 14 - \ 1 §10 - STUD \ACTUATION \ 1 : - 0 STUD AND CONTACT WEAR IN INCHES Fig. 11—Comparison of effects of wear on contact pressure of a relay. DESIGN FACTORS INFLUENCING RELIABILITY OF 997. Fig. 12—Magnetic circuit of a relay having embossed pole faces. Another instance where the effects of mechanical variations uponits performance have been largely nullified by design, is in the design ofslow release copper sleeve relays. To make most effective use of thecopper sleeve, which causes the delayed action, it is desirable to provideas low a reluctance as possible of the magnetic circuit when the relayis in the operated position. Instead of providing small non-magneticseparators in the air-gap between armature and the core as is usually y / y / EMBOSSED ;7^ /^ ^ -^ y /^ >^LAT / / ; DEVIATION IN DEGREES BETWEEN CORE ANDARMATURE POLE SURFACES Fig. 13—Comparison of flat and embossed pole surfaces and their magneticclosed circuit reluctance with misalignment. 998 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1952 done -with the ordinary (luick-to-release relays, for slow release relaysthe armature is allowed to contact the core, finish to finish. When plan
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
