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).
Page discussing the pros and cons of using a negative fuse in an automotive electrical system.
| Identifier | ExFiles\Box 61\2\ scan0200 | |
| Date | 24th October 1923 | |
| Contd. -2- EFC4/T24.10.23. (1) Battery ignition current may be used, passing to earth in the usual and simpler way. (2) Single pole lamps and lamp fittings may be used with their element of simplicity. (3) The system is protected by the negative fuse against earths on those live positive wires which are not protected by the distributing fuses. (4) In the event of the main negative fuse going this does not disconnect the dynamor from the battery, possibly leaving it on the lights, in such a way that over-voltage could do damage to the dynamo and lights, (and to the ignition if running be on battery ignition at the time). (5) By turning off the distributing switches and removing the main negative fuse, a test can be done on the rest of the system for insulation resistance or leakage (including or excluding from the tests the dynamo, as desired, according to the position of the charging switch. (6) The failure of the fuse in this position being less serious than in our present Goshawk position, the capacity of the fuse does not need to be anything like as great and therefore affords more protection against damage to the ammeter by short circuit. (7) The negative fuse renders unnecessary the positive fuse in the dynamo armature circuit, and also the present positive fuse in the field circuit, considered only, as it is at present, as a protection against a short on the dynamo field terminal. It also renders a fine field fuse less necessary, though perhaps this should be included, as shown in the diagram, as a protection against removal of the battery. (In the suggested system a fine field fuse is less necessary and useful than in the present Goshawk system where we have not got it). (8) It can easily be arranged that as regards the inspection lamp plug socket, the return connections do not pass via the earth, and are therefore not subject to this emergency fuse, so that in the event of this fuse going they would not be put out as at present. Contd. | ||