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).
Protection of the dynamo-battery system using fuses, comparing different fuse positions.
| Identifier | WestWitteringFiles\E\August1920\ Scan15 | |
| Date | 25th August 1920 | |
| To R.{Sir Henry Royce} from EFC. c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to Bn.{W.O. Bentley / Mr Barrington} c. to Da.{Bernard Day - Chassis Design} c. to PN.{Mr Northey} ORIGINAL EFC3/T25.8.20. X.2515 - PROTECTION OF DYNAMO-BATTERY SYSTEM X.294 X.295 BY FUSES. (1) The sole object of a main fuse in the dynamo-battery circuit would appear to be to prevent discharge of the battery, should the cut-out stick on. Therefore, it should be quite unnecessary with a perfectly reliable cut-out. (2) In the case of a dynamo such as the Smith with no control winding complication, there are two alternative positions for the main fuse, shown in diagrams Fig. 1 and Fig.2 on sheet attached. Each appears to have advantages and disadvantages not possessed by the other. (3) In Fig.1, the main fuse has to carry the field current from the battery with dynamo stopped and cut-out stuck, but not in Fig.2. Conversely with dynamo in normal operation, the main fuse has to carry the field current from the dynamo in Fig.2, but not in Fig.1. Therefore, the range between normal and abnormal main fuse currents in Fig.1 is greater than in Fig.2 by twice the amount of the field current, thus allowing a safer fuse. This is the advantage of the Fig.1 position. (4) If one can rely in every case upon the field fuse being replaced with the correct wire, Fig.1 should be the better arrangement. Should we, however, have to consider the possibility of the field fuse being replaced with incorrect wire Contd. | ||