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).
The design and testing of a new open type fuse compared to the cartridge type.
| Identifier | ExFiles\Box 166\7\ img080 | |
| Date | 15th September 1937 | |
| 2. but they appear to be incapable of action. The new type of open fuse now under consideration, automatically disposes of the troubles arising from the cartridge type. It therefore, only remains to be compared with its earlier form. (1) Trouble due to the fuse wire being stretched, fractured or cut, will be overcome, in the new fuse, providing the inner edges of the clamping strips, adjacent to the wire, are free from sharp burrs. (2) The provision in the design of the fuse carrier, of a reasonably apparent channel, and bridge support for the wire, ensuring that it does cross the break provided, should overcome the trouble of cooling, and the consequent variation in the fusing current. (3) The same features of design, together with the method of anchoring the wire, should remove the possibility of stretching it, or having too long a length, and thus overcome the variations in fusing current on this account. Bench tests carried out with three of these fuses mounted on a standard board, using 30 S.W.G. tinned copper wire, gave the following results. The values given represent in each case, the average of six observations; two of each fuse. Spring clip gap .080". Time taken Oxidising Contact Volt Drop. to melt. Current. at 15 amps. at 20 amps. (Open type) 3.9 seconds 15 amps. .111 volt. .174 volt. at 30 amps. From the foregoing it is apparent that the new open type fuse, in so far as the existing fuse faults are concerned will give less trouble than the cartridge type fuse. We are arranging for this type of fuse to be incorporated in a Distribution Box and for same to be fitted to 39-EX. to Sch. DCD.59. Rm{William Robotham - Chief Engineer}/RC.{R. Childs} | ||