458 



THE BELL SYSTEM TECHNICAL JOURNAL, APRIL 1951 



The large size-reduction relative to the 602 coil resulted in substantial 

 reductions in coil costs, notwithstanding the higher (per unit volume) cost 

 of the improved core-material due to the more complicated processes and 

 the high cost ratio of nickel to iron. The cost reduction in the coils was ac- 

 companied by a large reduction in the potting and installation costs. When 

 the coils were first standardized, the potting complements were similar to 

 those for the 602 coils but the cases were much smaller. Later on, larger- 



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Fig. 16 — Case size reduction resulting from coil size reduction. Cast iron cases con- 

 taining 200 88-mh. coils. At left: No. 612 (permalloy core) coils; total weight potted coils, 

 725 lbs. At right: No. 602 (hard iron dust core) coils; total weight potted coils, 1750 lbs. 



size cases potting complements of 450, 600, and 9(X) coils were standardized. 

 Using cases no larger than the previous maximum-size cases, potting com- 

 plements ranging up to about 2000 coils could have been made available, 

 if a demand for them should have arisen. Incidentally, the demand for the 

 900-coil cases was small. The extensively used complements in the range 

 300-600 coils proved to have a large value in relieving serious congestion 

 in the underground loading-vaults in metropolitan areas, notably New York, 



