The disappointing electrical performance of an ignition coil, with results from laboratory tests.
| Identifier | ExFiles\Box 164\5\ img098 | |
| Date | 20th November 1931 guessed | |
| -2- With regard to the ignition coil, we must confess to being disappointed with its electrical performance. Neither on the bench or on the road did its performance equal that obtained from our own coil or a coil of another make tested. On the road our criterion of performance for the ignition coil on the 20/25 HP. chassis is based on the "pick up" from walking pace to 20 M.P.H. on top gear on a level road. Under these conditions the Lucas coil misfired badly when thoroughly warmed up on the engine. We give below a summary of laboratory tests carried out on this coil:- (1) Winding quantities. Primary resistance at 20°C. ...... 1.00 ohms. Secondary " 19°C. ...... 5193 ohms. Primary impedance at a frequency of 50 cycles. ...... 3.77 ohms. Secondary impedance at frequency of 50 cycles. ...... 17900 ohms. Primary inductance ...... .0115 henries. Secondary " ...... 54.3 henries. (2) Temperature rise of coil windings. After running the coil for 4 hours in an atmosphere maintained at 80°C. with a contact breaker make ratio of .70 and speed 700 R.P.M., the temperature of the coil windings was found to be 140°C. At this temperature the coil failed to spark at all on 5.5 mm. third point gaps in air, but after allowing to cool the sparking recommenced as the coil recovered. (3) Current Consumption. The average current with .70 make ratio on the contact breaker we found to be 1.32 amperes at 200 R.P.M. dropping to .83 amperes at 1800 R.P.M. (4) Low voltage Test. At 10 volts we found the maximum distributor speed at which the coil would still regularly spark over 5.5 mm. gaps to be 1800 R.P.M. At 8 volts 580 R.P.M. | ||
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).