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 utility test of a slate slab used to simulate leakage on magneto and battery ignition systems.
| Identifier | ExFiles\Box 37\1\ scan 113 | |
| Date | 2nd June 1922 | |
| EFC. AB.2. X3199 2nd June, 1922 X.3199 SLATE SLAB FOR UTILITY TEST. X.430. The slate slab, originally intended for a set of spark gaps, but now arranged with various terminals along its length, has been tried as a leakage on both magneto and battery ignitions, for the utility test. On the former, using a Watford E.6 if two terminals, about 1 1/4" apart are connected across one of the gaps set at the normal 5.5 mm., misfiring occurs in varying degrees for practically all speeds and cam adjustments. Terminals wider apart do not seem to affect the spark very much. On the battery ignition, running under standard conditions with 6.5 mm gaps, the two extreme terminals shunted across a gap, cause misfiring. Any nearer terminals so placed put the spark out almost altogether. On the 5.5 mm gaps, however, rather nearer terminals may be used. It seems therefore that the slate leakage can be used with fair facility as a utility test on the RR battery ignition, and in a more limited way on magnetos. In order to estimate the resistance isxxxxxdxwhkhxx20xmfwixxxxxxx, of the slate, 100 volts d.c. was applied across two close terminals in series with inst.42 on the 150 volt range as an ammeter. Only a very small deflection could be obtained, of approximately one tenth of a division. This gives a resistance of the order of 15 megohms. FJA | ||