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).
Revised specification for the electrical operation of a 12-volt dynamo system for Mr. Cobham.
| Identifier | WestWitteringFiles\L\Jan1924-March1924\ Scan156 | |
| Date | 4th March 1924 | |
| X.294 - REVISED SPECIFICATION OF ELECTRICAL OPERATION OF DYNAMO FOR MR.COBHAM. (12 VOLT SYSTEM). The dynamo, after being run on load on the bench, clamped by means of metal clamps to an iron bed plate, for four hours with the commutator end cover in position, with a final ambient temperature not less than 18°C, and at a speed continuously adjusted to secure maximum ampere output, and operating on a battery at a dynamo terminal voltage not less than 14.0, shall comply with the following :- (1) The temperature of the metal of the carcase, as measured by the insertion of a thermometer bulb in a little metal oil bath in good metallic contact with the carcase, shall not exceed 75°C. (2) The open circuit voltage of the machine immediately after this shall not be less than 13.6 at a speed of 640 r.p.m. * (3) The output in this same hot condition shall exceed 9 amperes at an operating terminal voltage of 14.75 for the speed range 1200 to 2000 r.p.m. and shall exceed 10 amperes at some speed (about 1500 r.p.m.) in this range. Beyond this point the exact shape of the ampere output speed curve is not of such great importance, but it is considered that a characteristic drooping somewhat (say to not less than 6.5 amperes at 3000 r.p.m. or 6 amperes at 3500 r.p.m.) *NOTE:- 640 r.p.m. of dynamo corresponds to 8.8 m.p.h. (top gear). Contd. | ||