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).
Modified experimental connection of a shunt coil on a distribution box to prevent high voltage damage.
| Identifier | WestWitteringFiles\R\2October1927-November-1927\ 6 | |
| Date | 8th October 1927 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. E.{Mr Elliott - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} Ey. MODIFIED EXPERIMENTAL CONNECTION OF SHUNT COIL ON DISTRIBUTION BOX. One of the points that has occurred to us recently in connection with our standard electrical system (when thinking about auto switches, etc. upon which subject we hope to be able to give you further information shortly), is that the positive end of the shunt winding of the cutout should be connected to dynamo terminal C on the distribution box, instead of to dynamo terminal B, so that this small current is supplied through the field fuse. It is not that we want the current to be supplied through the field fuse particularly but the following possibility exists :- If fuse No.1 is removed or melted for any reason whilst the dynamo is running, or alternatively if the fuse, having been removed before the dynamo is started, and after the machine be started, the cutout be pushed in by hand, then we have in either case the condition that the cutout will remain in, its shunt coil being supplied direct from the armature with a high voltage, the excitation of the machine being provided by the battery. In this condition no harm can come to the generator, but the shunt coil can roast, and though I cannot say definitely, I seem to remember a case where we had to explain the roasting of the cutout shunt coil when the dynamo was in good order. By putting this condition so that the shunt coil positive is directly in connection with the dynamo field positive, this high voltage on the cutout coil cannot occur. We are making an experiment | ||