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).
Analysis of fuse configurations for electrical circuit protection, including a diagram for a four-contact switch.
| Identifier | WestWitteringFiles\D\February1920\ Scan9 | |
| Date | 3rd February 1920 | |
| Contd. -8- Ckl/T3.2.20. Such a fuse in combination with a field fuse would appear to give the best and most complete protection to the whole system. The use of such a fuse would involve altering the switch, unless one were content to put up with keeping the control and main negative terminals of the machine always connected together, this latter condition resulting in no abnormal flow of current. This could be done in the present Lucas switchbox with no basic alterations, as places are provided for two fuses. Another scheme would be to incorporate a fuse in a four contact switch in a manner diagrammatically represented thus :- [Handwritten diagram of a four-contact switch with a central fuse. The connections are labeled as follows: 'main to ammeter', 'negative', 'field', and 'control'. The central element is labeled 'Fuse'.] Conclusions. (a). The provision of a field fuse of suitable capacity as done by most makers and as at present standard with us, gives complete protection of the A type, but no protection of the B type. (b). The original Lucas practice of fitting a fuse of suitable capacity in the main negative circuit only, gives only partial protection of the A type also possible partial protection of the B type if the fuse is of sufficiently Contd. | ||