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 the shrinkage of a main switch's insulation materials due to heating.
| Identifier | ExFiles\Box 24\2\ Scan022 | |
| Date | 23th April 1920 | |
| X.1109. J.A. 130. X.3034. - MAIN SWITCH. X.1109. April, 23rd. 1920. Shrinkage of Insulation due to Heating - The main switch was placed on a metal plate, and heated by means of a gas ring placed under the plate. The temperature in the vicinity of base plate of the switch was maintained at 80 - 100°C for four hours. At the commencement of the test all nuts on the holding down bolts were tight. After the main switch base plate had reached a temperature of about 90°C. the cementing varnish of the micanite insulation under the main contact pillar began to run, some mica splittings being squeezed out under the compression due to the relatively greater expansion of the aluminium base plate to the steel bolts. Since the source of heat was from below the switch base plate the micanite insulation nearest the base plate is the one most affected. The Vulcasbestos insulation was not affected by the heat. After 4 hours the SWITCH was allowed to cool, and, when cold, it was possible to tighten the nuts on the two fixed contact pillar bolts to the extent of 3/4 turn each, and the single nut at the moveable contact pillar end by barely 1/8th turn. Contd. | ||