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 discussing issues with fuse arrangements and proposing a modification to improve reliability.
| Identifier | ExFiles\Box 61\2\ scan0321 | |
| Date | 17th February 1920 guessed | |
| Contd. -2- CK{Mr Clark}3/T. The fuses as arranged by you firstly, in the negative main only, and secondly, in both negative main and control main, only give partial protection of either type. The difficulty is that there is not sufficient margin between the normal and abnormal currents and therefore that fuses of sufficient current carrying capacity for normal conditions will not always fuse when desired under abnormal conditions. The placing of the fuse in the position as now suggested by us, virtually combines these two fuses into a single fuse carrying the sum of the currents of the previous fuses so far as abnormal conditions are concerned, but carrying no more current than either of the previous fuses taken singly under normal conditions. Therefore, this single fuse need be of no greater capacity than either of the previous fuses, but will more readily go, when intended, under the abnormal conditions, resulting from the sticking of the cutout. As there are places provided on your boxes for two fuses, we would like to know if you have any objection to making such a modification. Perhaps you would, in the first instance, send us a box along for experiment, in which this modification has been made in the way you think most fit. This matter appears somewhat important at the moment owing to the fact that we have had one or two complaints from our Test Dept. of the sticking of the cut-out and the resulting discharge of the battery. Yours faithfully, | ||