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).
Page discussing the effect of varying the primary gap in an ignition system, referencing accompanying curves.
| Identifier | ExFiles\Box 52\3\ Scan305 | |
| Date | 11th December 1917 | |
| Contd. -16- EFC {E. Fowler Clarke - Electrical Engineer} 2/T11.12.17. (5) Effect of variation of primary gap. The ratio period of make / total period is related to the amount of primary gap by a certain law depending upon the shape of the cam, etc. The value of the primary current at break, and the average value of the current consumption, may be mathematically expressed in terms of this ratio. Supposing other quantities to remain the same, we have calculated the variation in these two currents due to variation in this ratio and results are plotted in the accompanying curves, which show also the variation of observed average primary current consumption against primary gap for Remy 12 and for Remy 6. The energy drawn from the battery per spark produced, the stored energy of the magnetic field available for spark production and the efficiency of production of this field can also be expressed in terms of the ratio. Each of these three quantities is graphically represented on the ratio base by a curve, the first by the curveA of average current consumption, the second by curve C of squared current at break and the third by curve D. {John DeLooze - Company Secretary} It will be seen that the efficiency of magnetic field prodution is largest when the make ratio is small, hence the high efficiency of open circuit dyn systems, as before explained. The curves of observed current consumption are on a gap base, which is not quite thesame as the ratio base. Contd. | ||