NEW GENERAL PURPOSE RELAY 1035 



CORE PLATE 



Fig. 9 — Legs of the core are held in alignment by the core plute, which is forced 

 over the ends after the coil is assembled. 



a minimum of rebound when it is released from its operated position. 

 The conditions for reducing armature rebound were described previously* 

 and make it necessary to proportion the forces at the front and rear of 

 the armatiu'e properly. The magnitude and the ratio of these forces are 

 a function of the mass distribution of the armature. 



The magnet design must not only meet such functional recjuirements 

 as speed, sensitivity, etc., but it must meet these for several values of 

 armature travel as needed by the variety of contact combinations pro- 

 vided. Another requirement is that the relay be designed to fit on a 2-inch 

 mounting plate and this, in turn, restricts the width of the E-shaped 

 magnet core to slightly less than two inches. The relay is normally 

 mounted with the 2-inch dimension in the vertical direction to allow 

 the contact surfaces to be in vertical planes. The corresponding hori- 

 zontal dimension in which the relay can be mounted is 13^ inches except 

 for a few special cases. As described in more detail under the section on 

 Relay Performance, the improved magnet design has resulted in a reduc- 

 tion of the magnetic interference between mounted relays to values which 

 are negligible for most practical purposes. 



For comparison with the U type relay, the following typical constants 

 of the magnet are of interest (see Table I). The closed gap reluctance, 

 (Ro , is the reluctance of the magnetic circuit, excluding leakage paths, 

 with the armature operated and with the iron near maximum permeabil- 

 ity. The coil constant, G, is the ratio of the square of the number of 

 turns to the resistance for a full sized coil. The sensitivity, S, is a measure 



* E. E. Sumner, "Relay Armature Rebound Analysis", Bell Sijsteni Tech. J, 

 Jan., 1952, p. 172. 



