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).
Letter from Westinghouse Electric regarding specifications for magnet coils for a main switch and actuating box.
| Identifier | ExFiles\Box 24\2\ Scan146 | |
| Date | 24th March 1921 | |
| WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY. X 1109 March 24, 1921. Mr. M.{Mr Moon / Mr Moore} Olley, Rolls-Royce Co. of America Inc., Springfield, Mass. Dear Mr. Olley, X. 1109. X. 3331. X. 3034. X 3428. Replying to your letter of March 21st, I would recommend that you build up the magnet coils for your main switch and actuating box, according to prints enclosed and the specification given below: 1. SPOOL. This spool should be made up from a bakelite micarta tube with bakelite micarta plates cement-on each end. In winding a coil on such a spool it is necessary to use a mould to hold on end plates, It is our standard practice to place several such spools on the same shaft and wind several at the same time. In this way, the end plates are automatically held in place. 2. COIL. In case no change in performance is desired, the coil should be Wound with single silk covered enamelled copper wire. This insulation will give the same size coil as shewn on your prints, as the insulation space taken up by the enamel and silk is practically the same as the double silk covering. Single silk enamelled insulation is better than double silk. Where coil is given severe service, it is our practice to use D.C.C. enamelled wire, and where the room is not available for D.C.C. the S.C.C. enamelled wire is used. The information you have given me, is that this coil does not meet with severe service, and in view of the satisfactory performance with D.S.C. wire, it should not be necessary for you to go to the cotton covered enamelled wire. It is standard American practice to wind coils for ordinary service, such as cutouts, relays, etc. from bare enamelled wire. This construction gives practically no trouble; at the same time, the single layer of silk on the enamel gives an added factor of safety. In case you desire better performance without increasing size of your coil, it is possible to | ||