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).
Letter from The M-L Magneto Synd. Ltd. regarding production tests of Ignition Coils.
| Identifier | ExFiles\Box 164\5\ img010 | |
| Date | 6th January 1931 | |
| X6058 TELEGRAMS: "CARLTON. COVENTRY." TELEPHONE 5001-2-3 The M-L Magneto Synd. Ltd. VICTORIA WORKS, COVENTRY. Messrs. Rolls-Royce, Ltd., DERBY. [STAMP: RECEIVED 7 JAN 1931] YOUR REFERENCE EFC2/AD OUR REFERENCE EAW/EE 6th January 1931. Dear Sirs, Dr. Turner has passed on to the writer your letter of the 30th December enquiring in regard to production tests of Ignition Coils. In reply to your queries we would say that we do not consider it necessary to test the coils with spark gaps under pressure, as spark gaps under pressure are generally unreliable, and it is much better to test them with a correspondingly larger gap working at atmospheric pressure. We ourselves use Annular Gaps, as we find these are more consistent than 3-point ones, and do not burn away so rapidly. We recommend that the Endurance Test be run on a gap with a normal working voltage of about 10,000 to 11,000 volts. We attach a curve giving data from which such gaps can be constructed. As regards the question of temperature, it is not our practice to artificially heat the coils for this purpose, but if the Endurance Test lasts an appreciable time, say 2 or 3 hours, the coil is certain to attain a | ||