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).
Continued page detailing the properties of mineral oils for insulation and testing procedures.
| Identifier | ExFiles\Box 24\2\ Scan087 | |
| Date | 11th August 1920 | |
| R.R. 235A (100 T) (S.H 159 11-8-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2500 -4- Contd. lowers insulation. Alkalics and sulphur harmful. Mineral oils less liable to carbonize than other kinds in contact with an arc. Best oils puncture at about 5 times voltage for air, i.e. about 9,000 volts per mil. The less viscous the better. To test for water, immerse red-hot iron, spluttering if damp. Petroleum sometimes shows a puncture voltage of 17,000 to 26,000 per mm. | ||