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).
Investigation into a faulty coil from chassis 58-S7, identifying an intermittent short-circuit in the secondary winding.
| Identifier | ExFiles\Box 46\3\ Scan208 | |
| Date | 31th March 1924 | |
| COPY. EFC. WA.{Mr Wallis}16. 31.3.24. RE FAULTY COIL OFF CHASSIS 58-S7 (See EP{G. Eric Platford - Chief Quality Engineer}/HS{Lord Ernest Hives - Chair}35/27.3.24). On investigating the cause of failure of the above coil, it was found to be an intermittent breakdown of the secondary winding. The continuity of the windings being O.K. it was not considered that a break in the winding had occurred but that the winding was being periodically subjected to a short-circuit. This was confirmed by placing the coil on the rig and observing the increase of primary current at the moment when the secondary broke down. This was 1.9 amperes in place of the normal 1.1, which 1.9amps. tallied with the reading of the instrument on the secondary winding being externally short-circuited, when the coil was sparking satisfactorily. Also when the coil was open-circuited when working, sparks could be heard jumping across the winding inside. The ballast resistance was also tested to the standard production specification and found to be O.K., with the exception that the brass terminal ferrules were rather be loose. With regard to the heating of the ignition units, this would probably be due to the increased current taken by the coil at times when the secondary short-circuited. EFC /HEW. | ||