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).
Wiring scheme for an accumulator switch and green light indicator, and the design of a delicate field fuse.
| Identifier | WestWitteringFiles\T\2July1928-December1928\ Scan036 | |
| Date | 20th July 1928 | |
| EFC. FROM R.{Sir Henry Royce} C. to BJ. HS.{Lord Ernest Hives - Chair} ORIGINAL ACCUMULATOR SWITCH, & GREEN LIGHT SCHEME. X7740 X4040 X7860 E.{Mr Elliott - Chief Engineer} is correcting his diagram LeC. 2570. As far as we can see the bestplace for taking the ends of the fine wire of both the automatic accumulator and the green light charging indicator would be from terminal C. because in this position it would not get the high electromotive force from the dynamo in case the dynamo, plus fuse, failed, and neither would it receive a large current from the battery in the case of a local short on these fittings, even when the charging switch is in the 'on' position. Our original position for connecting the fuse was not good, as you point out, and your position across the battery would have been wrong, because we could not have stopped either the lamp or the coil from working when the switch was turned off. There does not seem much difference between connecting to terminals 1, 2, and C., but we think C. the best. If you do not agree please write and let me know. Regarding the delicate field fuse, I am a little bit inclined to think that as arranged in the glass tube there is a tendency that it might break due to the difference of expansion and temperature between the wire and the glass tube. It suggests that the fuse wire should be in the form of a spiral, and so not be overstressed due to difference of expansion. The one on the 20HP. that I have been using failed for no apparent reason, and may have been due to the above suggested cause. R.{Sir Henry Royce} | ||