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).
Ignition coil failures and proposing experimental modifications to the windings to prevent electrical breakdown.
| Identifier | ExFiles\Box 69\1\ scan0174 | |
| Date | 31th December 1928 | |
| X8770 To EY. from EFC. c. WY/RD. c. Mr. Brock. EFC3/T31.12.28. FAILURES OF IGNITION COILS. Attached please find copy of my assistant's report WD.{Mr Wood/Mr Whitehead}23. The bench tests referred to in the first para. are tests primarily for the purpose of testing H.T. wiring in which the highest voltage normally obtainable from ignition coils is imposed upon this wiring. The breakdown referred to occurred probably from first to second layer of the secondary, but in any case in the first few layers. We are of the opinion that it may be worth while instructing an ignition coil experimentally with standard windings (coarser gauge primary), but with the following constructional modifications :- (a) The primary wound parallel like the parallel wound coils we have had with a good thick layer of insulation between each coil layer, making sure that the alternate ends are well insulated, not with additional insulation, but if considered necessary, by stepping back one turn. The idea is to have a primary finished fairly parallel but also reasonably well insulated. (b) The secondary as standard, wound on a stiff paper roll wound over the primary. It is understood of course that such winding will occupy more room and will lower the thickness of air space between the winding and the bakelite case. We do not now regard this of so much consequence, but it [the coil] must be well enough insulated to prevent electrical breakdown. Will Mr. Brock please note that we have one or two coil bobbins and cases (from unwound coils) which can be utilised for the purpose suggested. EFC. | ||