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).
Test results on four different cable insulation materials, including voltage breakdown and flammability.
| Identifier | ExFiles\Box 58\1\ Scan192 | |
| Date | 1st December 1929 | |
| -3- EFCA/AD6.12.29 contd. Effect on Super Clover - none appreciably " " Helsby - slight softening. " " Maconite - none appreciably. All four samples ignited with the same degree of moderate inflammability when exposed to a naked flame. Details of the tests under section (B) with comparative results are as follows :- (4) A.C. voltage breakdown test after 24 hours immersion of the central portion of a cable in water at normal atmospheric temperature, the test being conducted whilst the cable is still immersed. Cloverite - successfully withstood 19,000 volts R.M.S. for 15 mins. Super Clover - ditto Helsby - broke down at 19,000 volts R.M.S. Maconite - successfully withstood 19,500 volts R.M.S. for 15 mins. (5) A sample length of cable kept at 150°C. for one hour and allowed to cool, after which it is bent into a loop of 1" internal diameter and immersed in water for 4 hours. The cable in this condition tested for breakdown and the breakdown voltage noted. Cloverite - successfully withstood 19,100 volts R.M.S. for 15 mins. Super Clover - ditto Helsby - broke down at 17,000 volts R.M.S. Maconite - successfully withstood 19,500 volts R.M.S. for 15 mins. | ||