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 methodology for measuring layer voltage in a standard ignition coil with a tapped secondary winding.
| Identifier | ExFiles\Box 69\2\ scan0009 | |
| Date | 15th May 1930 | |
| WE.24. X8712 15.5.30. X.8712. STD. IGNITION COIL WITH TAPPED SECONDARY WINDING FOR LAYER VOLTAGE MEASUREMENT. X.918 We have now suitably arranged this coil, using a rectifying valve, condenser and ballistic instrument, for measuring the primary voltage and secondary layer voltages. The voltage measuring apparatus which comprises valve with filament battery, throw over switch, .3 mf. condenser and Cambridge Pyrometer instrument No.14504 shunted by a 130 ohm resistance, has been calibrated by connecting up to a 50~ A.C. supply and then proportioning out the peak volts to scale deflection by referring to the scale deflection - millivolt calibration of the instrument. The coil primary was connected up to a 17.5 volt supply and standard contact breaker running at 700 r.p.m. and the secondary H.T. terminal to a third point spark gap. Voltage measurements were then taken the time allowed, after preliminary experiments, being on the average about 5 mins. each measurement to allow the condenser to charge up to the maximum voltage particularly in this case where there might be intermittent surging. The following table gives the results obtained with firstly, the secondary gap calibrated to discharge at a peak voltage of 8000, and secondly at 9000 volts, this latter voltage being the maximum regular sparking voltage of the coil. | ||