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 comparative testing of low tension cables.
| Identifier | ExFiles\Box 167\3\ img136 | |
| Date | 19th January 1939 | |
| 6110 To By.{R.W. Bailey - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to By/RD. Rm{William Robotham - Chief Engineer}/RC.{R. Childs}8/JH.19.1.39. re Low Tension Cables. In order to obtain a figure of merit on the Repault L.T. cables we have subjected the samples submitted, together with samples of standard cable, to our specification tests EL.1 and EL.13. We find that the Repaults cable is not as good as the standard Helsby, for resistance to oil and petrol penetration, but is very good with oil only. The laquer or varnish finish becomes brittle with heat, and easily cracks when the cable is bent. The insulation breakdown voltage is much lower than on our standard cable, but is high enough to prevent electrical breakdown, provided the cable remains mechanically sound. There is no sulphur effect on the conductors which are clean and well tinned. On the heating test the standard cable withstood the extreme conditions better than the Repaults, on which the laquer or varnish finish became brittle, and easily cracked at the end of the test. The oil and petrol test proved the standard cable good, none having penetrated to the rubber. The Repaults black laquer finish cable was good in this respect, no penetration taking place. The Repaults aluminium laquer finish and the varnish finish, were not good, penetration had taken place causing the rubber to become swollen. Using oil only, all the above cables were good. The standard Thiokol horn cable gave good results on all tests. The attached breakdown figures were obtained. Rm{William Robotham - Chief Engineer}/RC.{R. Childs} | ||