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 on insulating sleeves moulded with a new Bakelite powder, grade X20-5.
| Identifier | ExFiles\Box 61\1\ scan0208 | |
| Date | 19th May 1932 | |
| TESTS ON BAKELITE STDS POWDER GRADE X20-5. Tests have been carried out on two sets of insulating sleeves moulded with a new Bakelite powder. One set of sleeves had been baked for five minutes, the other set for ten minutes. The sleeves having had ten minutes baking were first tested. The volt-microampere ratio was measured at atmospheric temperature (18C) and was found to be practically infinity. Similar results were obtained from measurements taken at 40°C and 80°C. At a temperature of 120°C the insulation value fell to 1852 megohms. The sleeves having had five minutes baking were next tested. Until a temperature of 80°C was reached the leakage current was not measurable. At 80°C the insulation value was 4267 megohms, this figure fell to 1750 megohms, at 120°C. One of the sleeves was soaked for 24 hours in water and after drying a voltage of 15,000 R.M.S. was applied for five minutes, during which period no breakdown occurred. One noticeable point was the shrinkage after the immersion in water. The new powder is superior to the present standard powder as far as conductance figures are concerned. The figures obtained were :- Practically zero. up to 100°C. .0005 micromhos at 120°C. The standard figures are :- .003 micromhos at 80°C. .025 " " 100°C. Mechanical Test. The insulation testing electrodes were placed in the ferrule, and weights were suspended from one electrode, the load was increased until the ferrule broke at 68 lbs ins. This new powder therefore appears to be more suitable for production than the present standard, it is also cheaper than the Novite at present used. | ||