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).
Car electrical equipment, focusing on the testing of earths and specifications for various fuses.
| Identifier | ExFiles\Box 65\2\ scan0139 | |
| Date | 29th September 1928 | |
| To R.{Sir Henry Royce} from EFC. c.c. RJ. X7240 EFC3/T29.9.28. CAR ELECTRICAL EQUIPMENT. X8780 X7240 Reference your EL/M21.9.28, we have not made a succession of earths on the electrical system deliberately and systematically to test the blowing of the fuses. We have, however, noted many cases of accidental earths in the ordinary course of events in the Expl. Dept, and that the main and distributing fuses go satisfactorily in circumstances in which they might be expected to do so. Concerning the query re 200 ampere fuse for heavy motor current circuit, I do not know of any case of serious consequences resulting from an earth on this side circuit, such as might occur and has occurred on less heavily fused wired circuits improperly fused, and in the circumstances I do not think it is called for. It would be difficult also to avoid relatively considerably loss of voltage in the fuse in normal operation which loss we consider we can ill afford on the smaller and less efficient motor. With regard to the field fuse it is, as we have previously reported, the case that the actual fusing current has to be, for safety in normal operation, a good deal higher than we would like for the prevention of damage in the event of a fault, e.g. open battery circuit. We know that it is not yet impossible on our present standard system for damage to occur to the dynamo through overheating, as a result of excessive voltage, should a break occur in the main battery circuit. Contd. | ||