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).
Comparative test results of standard ignition H.T. cable versus a new experimental type from Johnson and Phillip.
| Identifier | ExFiles\Box 167\3\ img082 | |
| Date | 30th August 1937 | |
| To By/RD from Rm{William Robotham - Chief Engineer}/RC.{R. Childs} c. RM.{William Robotham - Chief Engineer} Rm{William Robotham - Chief Engineer}/RC.{R. Childs}15/MH.{M. Huckerby}30.8.37. Johnson and Phillip Ignition H.T. Cable. Owing to the short life, on the car, of the standard ignition H.T. cable, grade 673, made by British Insulated Cables Ltd., tests on other makes of H.T. cable were initiated. Samples of cable were obtained from Messrs.Johnson and Phillips, which, together with samples of the standard cable, were subjected to a series of comparative tests. The tests carried out, were on the following lines :- (1) The dielectric strength of the insulation, as judged by the effect of applying 20,000 volts (RMS) across it, for a period of 15 minutes. (2) The effect of heat on the insulation, by baking it at 150°c for 5 hours. (3) The effect of oil, by keeping it immersed in oil for a period of 24 hours. (4) The effect of petrol, by keeping it immersed in petrol for 24 hours. (5) A test under service conditions of combined temperature and electric stress, by holding the cable in contact with metal at 80°c, and applying a voltage of 10,000 volts, until the cable broke down. On tests 1, 2, 3, and 4, it was found that there was practically no difference between the two types of cable. As regards test 5, however, there was a big difference, the sample of experimental cable standing up for 500 hours, and being in good condition on removal. Compared with this, the best samples of standard cable, became cracked in the insulation, early in the test, and broke down at the end of 94 hours. Cable of this experimental type was then fitted to cars B.56.BN.{W.O. Bentley / Mr Barrington} and 6.B.IV. On the first it ran 9,847 miles, and on the second it ran 17,000 miles in France. In both cases it was satisfactory. | ||