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).
High tension circuit misfiring, attributing the issue to coil insulation stress and proposing tests with new experimental coils.
| Identifier | WestWitteringFiles\D\October1919\ Scan34 | |
| Date | 24th October 1919 | |
| Contd. -6- EFC10/T24.10.19. the conditions of the high tension circuit fairly easy to overcome, there is no difficulty in bringing about regular firing, and the fact that such missing as does occur, occurs at the lower speeds where the energy of the spark should be greater would seem to point to the idea of the missing fire being due to potential stress in the coil insulation which it is not always able to stand up to. We feel that the missing fire under bad conditions is to be explained by the fact of the extra high tension circuit resistance and capacity, resulting in the condition that the coil has to work at a higher voltage on its high tension terminal and is called upon to produce a greater quantity of electricity in its oscillatory discharge. We have shewn mathematically that on the secondary discharge increased voltage and increased amplitude of oscillation go together, so that the effect of additional capacotu in the circuit demanding a greater quantity, would raise the voltage at the coil, and so possibly cause a temporary breakdown. In order to thrash out this point we have asked for two experimental coils to be made each of which are wound with only 16,000 secondary turns instead of 21,000, one of which is wound with the same gauge of secondary wire and so leaving ample space for secondary insulation, and the other of which is wound with a slightly higher gauge of secondary wire, and leaves about the same space for insulation. When these coils are ready after the usual bench tests, we hope to have an Contd. | ||