From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Performance of Smith, Lucas, and C.A.V. electrical cutouts.
| Identifier | WestWitteringFiles\F\May1921\ Scan59 | |
| Date | 31th May 1921 | |
| To R.{Sir Henry Royce} & E.{Mr Elliott - Chief Engineer} from EFC. c. CJ. & FN. c. En. & Ry. c. Da.{Bernard Day - Chassis Design} & EW. c. EWT. for R.R.Inc. ORIGINAL EFC6/T31.5.21. X.3771 @ X.1815. SMITH (AND OTHER) ELECTRICAL CUTOUTS. Further to our EFC2/T19.4.21 and EFC4/T18.5.21 in which the performances of the new Lucas special cutout and the C.A.V. type D cutout were reported, herewith please now receive copy of a table of operation of these cutouts, together with operation of two recently received Smith cutouts Nos. 7914 and 11846. Cut-out No.7914 was wound by the makers in accordance with our suggestion with a shunt winding of part Eureka and part copper (about half the resistance in each metal), whereas cut-out No.11846 was wound by the makers with copper only, as they considered that owing to the size of the cutout the addition of the Eureka was unnecessary. Their contention appears to be correct, as the figures for both cutouts, after being adjusted by us to suit our specification of cold operation, came within our limits for hot operation, although the one with copper only is slightly later than the one with Eureka and copper. Figures are given both for the operation of the cutouts as received from the makers and for the operation after being adjusted by us to suit our specification for cold operation. It will be seen that the operating voltage cold at which we set the cutouts is rather smaller than that of the makers, but we have reason for believing that on the whole this setting is | ||