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 specification of safety spark gaps in breakdown voltage versus millimetres for different magneto types.
| Identifier | ExFiles\Box 4\5\ 05-page270 | |
| Date | 27th May 1924 | |
| Contd. -3- EPC2/T27.5.24. One of the things Mr. Watson said was that he considered the safety spark gap should be specified in breakdown voltage, and he suggested the figure of 12000 volts. He said it was very uncertain merely to specify it in millimetres as it varied according to the form of the points. I explained to him that we were quite aware of this, but as a practical rough and ready method, H.T. gaps were always talked of in millimetres by the testers. I suggested to him that even then we are not entirely free from the phenomenon of impulse ratio, to which he partially agreed, but ultimately we mutually arrived at the probability that this feature is reasonably the same for the different types of magneto that might be under consideration. Mr. Turner of the LucasElectrical Co. is due to come this afternoon on exactly the same lines as the visit of Mr. Watson.yesterday. It is also intended to keep Messrs. Norths advised of our requirements. E.T.C. EFC. | ||