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).
Potential magneto failure due to increased resistance in the secondary circuit.
| Identifier | ExFiles\Box 70\3\ scan0376 | |
| Date | 24th June 1930 | |
| W/S. To PN.{Mr Northey} from EFC. X8783 EFC4/AD24.6.30. X.8783. CHASSIS 1-WJ. X.7791. In your note PNL/WT23.6.30 you enquire of us if we understand the paragraph which you have marked in red in memo A20/H2O.6.30. We do not understand this paragraph and feel that it has been rather carelessly written, possibly in the hope of getting away with some sort of explanation which is not entirely satisfactory. If the "increased resistance in the secondary circuit" to which they refer implies an increased resistance external to the magneto, such should invariably be taken care of by the safety gap which is present in any magneto. Assuming that the safety gap was set correctly, the failure appears to have been due to faulty slip ring insulation either internally or superficially. It is not impossible that this may happen as a result of superficial condensation of moisture on the ring, but generally speaking all the H.T. insulating parts of any magneto should be made to withstand indefinitely the breakdown potential of the safety gap in extreme circumstances. We should think that it would be probably as well to ask the makers for a somewhat more satisfactory explanation of the failure than they have given. EFC. | ||