SLOA\- REI.KASi; i;i;i,\^ DKSIOX 217 



\alue specified, subject to the capacity of the adjustment springs to 

 supply the necessary increase in load. 



In the common case for which only (he mininnnn time is of circuit 

 importance, the release value is chosen without reference to the hold 

 \alue, solely for the purpose of assurinp; that the I'elay will not lock up 

 indefinitely. This procedure takes advantage of the simpler reiiuirements 

 of this case l)y widening \\w adjustment tolerance and rcdncing adjust- 

 ment effort. 



7 CONCLUSIONS 



The relation between the release time of slow release relays and the 

 design parameters can be more accurately expressed in analytical form 

 than the other time characteristics of relays. These analytical relations, 

 as presented in this article, can be used for the estimation of release time, 

 and particularly for the determination of the effect on this time of varia- 

 tions in the design parameters. The need for a low reluctance magnetic 

 circuit makes the performance of slow release relays highly sensitive to 

 dimensional and material variations, and adjustment is required to 

 assure the timing limits required in their use. Such use usually permits a 

 \\ide spread in release time, provided a minimum value is assured. 

 Advantage is taken of this in providing slow release relays which perform 

 their function at a minimum cost in manufacture and use, materially 

 lower than that for the construction and adjustment practices which 

 would be required for closer timing control. 



ACKNOWLEDGEMENTS 



The specific references made to individuals and prior studies do not 

 include all the work which has been drawn on in the preparation of this 

 article. In particular, much of the discussion of the applications of the 

 analysis is based on work carried out by M. A. Logan, Mrs. K. R. 

 Randall, O. C. Worley and others in the development of the AG relay. 



REFERENCES 



1. F. A. Zupa, The Y-tvpe Relay, Bell Lab. Record, 16, p. 310, May, 193S. 



2. H. X. Wagar, The U-type Relay, Bell Lai). Record, 16, p. 300, May, 1938. 



3. A. C. Keller, A New General Purpose Relay for Telephone Switching Systems, 



B.S.T.J. 31, p. 1023, Nov., 1952. 



4. R. L. Peek, .Jr., and M. A. Logan, Estimation and Control of Operate Time of 



Relays, pages 109 and 144 of this issue. 



5. H. N. Wagar, Slow Acting Relays, Bell Lab. Record, 26, p. 161, April, 1948. 



6. R. L. Peek, Jr., and H. N. Wagar, Magnetic Design of Relays, page 23 of this 



issue. 



