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 a coil with an outside primary winding, detailing its failures and required modifications.
| Identifier | ExFiles\Box 164\5\ img064 | |
| Date | 4th April 1931 | |
| X6017. By from Hs{Lord Ernest Hives - Chair}/HEW. C. E.{Mr Elliott - Chief Engineer} Hs{Lord Ernest Hives - Chair}/HEW2/ADL4.4.31. COIL WITH OUTSIDE PRIMARY WINDING D.SCH.419. We have bench tested this coil preliminarily and have found it to be very inefficient. On open circuit, sparking over from the primary circuit to the secondary circuit is almost continuous, the H.T. leakage and spark over distances being too small. The sparking on 5.5 mm. gaps is also irregular even with the coil cold and in series with an old standard (single) type ballast resistance. On the heating test the coil secondary output is reduced so much that no sparking at all could be observed on 5.5 mm. gaps and the coil practically petered out. This coil in its present state is useless and requires modification. Our criticisms are :- (a) The winding inductances are much too low owing primarily to the poor iron circuit. (b) Two fairly large brass washers are fitted to the end of the core which must affect the magnetic circuit. (c) The iron case is of too thick a gauge and should be made preferably with a seam. The thin gauge case with a seam would, we suggest, provide a much less conductive path for eddy currents vide Delco Remy, Lucas, Marelli etc. (d) The primary could be wound straight over the secondary to make a closer coupling and should be narrower to obviate spark overs. (c) The whole coil is much too small for the working conditions of an R.R. chassis. | ||