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 and conclusions on resistance changes with temperature for various coil cases.
| Identifier | ExFiles\Box 69\1\ scan0048 | |
| Date | 26th April 1927 guessed | |
| -2- Contd. corresponding leakage current from 20 micro-amperes up to the full scale deflection of 960 microamperes. With the first coil case, readings were taken at 20ºC, 40ºC, 60ºC, 70ºC, 80ºC, 90ºC and 100ºC up only, after which it was decided to take similar readings as the temperature fell. After the third case had been tested, it was thought desirable from the manner in which the leakage increased to take an additional reading at 50ºC. Below are tabulated the results of these tests. Conclusions. In general, there is a rapid fall in resistance with rise in temperature up to about 60ºC, above which temperature there is comparatively very little further drop in temperature. Resistance (Megohms). Case No. 20ºC 40ºC 50ºC 60ºC 70ºC 80ºC 90ºC 100º 1. Up. 490 67.8 - 13.9 3.35 2.55 1.49 1.26 Down. - - - - - - - - 2. Up. 95.5 39.3 - 2.99 2.09 1.42 1.22 - Down. 199 262. - 3.94 2.30 1.43 1.19 - 3. Up. 199 43.6 - 4.88 2.05 1.35 1.03 - Down. 346 39.3 - 7.83 3.88 2.05 1.03 * 4. Up. 56.0 11.1 3.64 1.73 1.47 1.27 - * Down. 122 15.7 7.74 3.18 1.88 1.27 - * 5. Up. 131 13.9 5.49 2.73 1.49 1.18 1.15 - Down. 209 25.6 10.8 4.37 3.32 1.64 1.15 - 6. Up. 172 46.2 16.0 5.31 2.65 1.96 1.77 1.03 Down. 233 65.5 33.5 10.3 5.31 2.75 2.08 1.03 *Instrument needle off the scale. Repeated heatings tend to improve the characteristics of the material, by raising the temperature corresponding to a given value of resistance. Doubtful cases produced might therefore be improved by carrying them through cycles of temperature. For testing purposes a temperature of 80ºC appears to be high enough. EFC/C.A.Pignatt | ||