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 report for material leakage and breakdown voltage at varying temperatures.
| Identifier | ExFiles\Box 61\1\ scan0103 | |
| Date | 24th April 1930 guessed | |
| RR·238 (150 BKS.) (DB{Donald Bastow - Suspensions} 461·8·12·24) MP 306975 ROLLS-ROYCE LTD. INSTRUCTIONS. To________________________ Order No._________________ Customer's No.__________________ | Temp °C | 20 | 40 | 60 | 80 | 100 | |----------------------|----|-------|-------|-------|-------| | leakage micro-mho mils | 0 | ·080 | ·211 | ·654 | ·758 | These results it will be seen are considerably better than those obtained with the last sample; or the sample tested in Oct 1926. Tests with a falling temperature were not made. Breakdown. A piece was tested on the H.T. transformer as received and broke down at 18700 volts RMS or 706 peak volts per mil. Afterward the piece used for the leakage tests withstood 19300 volts RMS or 780 peak volts per mil without breakdown. The material now seems suitable for use. Signed: FJH.{Fred J. Hardy - Chief Dev. Engineer} This Sheet must be filed on completion of the work. | ||