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 report tabulating the results of resistance (Megohms) measurements at various temperatures.
| Identifier | ExFiles\Box 39\3\ Scan286 | |
| Date | 8th June 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 20°C, 40°C, 60°, 70°, 80°, 90°C and 100°C up only, after which it was decided to take similar readings as the temper- ature 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 50°C. 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 600C, above which temperature there is comparatively very little further drop in temperature. Resistance (Megohms). Case No. 20°C 40°C 50°C 60°C 70°C 80°C 90°C 100°C __________________________________________________________________________ 1. Up. 490 67.8 - 13.9 3.35 2.85 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 charac- teristics of the material, by raising the temperature corres- ponding 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 80°C appears to be high enough. EFC/C.A.Pignatt. | ||