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).
Tests conducted on the effect of a choke and condenser on the 20/25 HP battery ignition system for tank engines.
| Identifier | ExFiles\Box 163\2\ img031 | |
| Date | 11th January 1933 | |
| X6008 E.{Mr Elliott - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Wst. c. By.{R.W. Bailey - Chief Engineer} Mx.{John H Maddocks - Chief Proving Officer} c. F.{Mr Friese} Hs{Lord Ernest Hives - Chair}/Wst.6/KT.11.1.33. EFFECT OF CHOKE ON THE OPERATION OF THE 20/25 HP. BATTERY IGNITION ON TANK ENGINES. In accordance with your request, we have carried out tests on our standard 20/25 battery ignition using a choke and condenser inserted in the L.T. side of the coil. This choke and condenser was forwarded to us by the War Office, and is used by them for other cars where wireless receiving sets are fitted. The value of the choke received was as follows :- Resistance .050 ohms. Inductance .0020 henries. The value of the condenser was 3 microfarads. We found that by inserting this choke and condenser, very little effect was observed on the functioning of our ignition at the highest speeds at which the engine will run. In view of the War Office's request that we should try a still larger choke we put in another choke of approx. the same value inductance, in order to ascertain the further effect of doubling the choke inductance. The complete results of our tests are as follows - (a) Volts given by the coil with a ¼ megohm leak across the secondary winding, this representing the normal loading of the ignition system, was at 2000 distributor r.p.m., 6200 volts. (b) By inserting the choke sent by the War Office, the volts were reduced to 5600. (c) By additionally inserting our own choke the volts were still further reduced to 4200. These figures are still in excess, we consider, of the voltages attained by the sparking plugs at these engine speeds, so that we should not anticipate any misfiring from the ignition even with the .0040 henries inductance inserted. The reason the addition of these chokes has so little an effect is due to the fact that our coil has | ||