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).
Electrical system and dynamo fuse protection for the 20 HP model, comparing it to the 40/50 system.
| Identifier | ExFiles\Box 51\2\ Scan121 | |
| Date | 12th July 1923 | |
| To R. {Sir Henry Royce} from EFC. {E. Fowler Clarke - Electrical Engineer} c. CJ & BJ. c. to BY. {R.W. Bailey - Chief Engineer} PN. {Mr Northey} c. to EP. {G. Eric Platford - Chief Quality Engineer} Hs. {Lord Ernest Hives - Chair} X4338 EFC {E. Fowler Clarke - Electrical Engineer} 1/T12.7.23. X.4338 - 20 HP. ELECTRICAL SYSTEM. Referring to RL/M10.7.23, there is, of course, a difference in addition to those you mention that the 40/50 system is provided with a dynamo field fuse, which has appeared to be a reasonable protection against over-voltage in this case. Though there is a fuse in the field circuit on the 20 H.P. system, this, presumably in order to avoid duplication of sizes of fuse wire required, only gives protection from earths or short circuits on the field winding. It is suggested that it would be better to place your suggested warning in a suitable position on the battery box. An idea that has occurred to us is to instruct or warn that the battery positive wire, if removed from the battery, should be grounded to the frame (a suitable grounding terminal possibly being provided). (It might be considered worth while to arrange for this to be done automatically). In this case, if the charging switch is on and the dynamo is run, the dynamo is alternately self-excited and de-excited by being short circuited by the contacts, and the cutout vibrates and gives audible warning that the charging switch is left on. At the same time the ammeter needle oscillates giving visible warning. EP. {G. Eric Platford - Chief Quality Engineer} , however, considers that even with this arrangement one could not rely on every customer | ||