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).
Specification of laboratory tests for enamelled copper wire for ignition coil secondary windings.
| Identifier | ExFiles\Box 69\2\ scan0019 | |
| Date | 18th September 1930 | |
| ENAMELLED COPPER WIRE FOR IGNITION COIL SECONDARY WINDINGS. SPECIFICATION OF LABORATORY TEST. (1) Immerse wire in (a) 20% solution of caustic soda for five hours. (b) 20% sulphuric acid for five hours. (c) 20% nitric acid for five hours. and note effect on enamel, if any. (2) Test whether the enamel can be scraped by the friction of one wire on another. (3) Test wire in tension for effective tensile strength by noting the breaking load. (4) Test whether the flexibility of the enamel on a sample of wire which has been maintained at 150°C. for four hours is great enough to allow of the wire being wound round a rod of six times the wire diameter without the enamel showing cracks when examined with a magnifying glass. (5) Wind on a metal spool 1" in diameter a layer of wire about 2" long and test the breakdown voltage between the wire and the spool, which voltage shall not be less than 300 volts. | ||