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).
Report comparing the insulation properties of 'Maconite' and 'Glover' H.T. ignition cables after environmental exposure and voltage testing.
| Identifier | WestWitteringFiles\P\2July1926-September1926\ Scan122 | |
| Date | 31th August 1926 | |
| WB.{Mr Brazier/Mr Bell}99. 31.8.26. "MACONITE" H.T. IGNITION CABLE. In a previous report on this cable (see WB.{Mr Brazier/Mr Bell}84) it was mentioned that a sample of Maconite and Glover cable had been exposed to the light and atmosphere. These samples have now been tested on the H.T. transformer in the laboratory, after having been exposed for four months. The voltage across the insulation was gradually raised by 2,500 volt increments at 5 minute intervals, up to 17,500 volts, R.M.S., a test voltage considered suitable for sustained test as a result of earlier trials. After 35 mins. at this voltage the Glover cable sample broke down, examination shewing that cracking of the rubber had occurred first. The Maconite cable sample withstood this voltage for 2 hrs, after which the voltage was raised to the maximum possible, 19,300 R.M.S. without causing a breakdown and without cracking the insulation. These tests shew that light and atmospheric oxidation must apparently take a long while to seriously impair the insulation properties of H.T. ignition cables, as these results are about the same as obtained prior to exposure. In any case the Maconite appears to be definitely superior. We suggest as a final test, obtaining a sample of each cable after it has completed 10,000 miles on a car and testing it similarly on the H.T. transformer. EFC/H.E.West. | ||