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).
Clarifying the electrical wiring for the cutout, green lamp switch coil, and green lamp.
| Identifier | WestWitteringFiles\S\June1928-August1928\ Scan105 | |
| Date | 26th July 1928 | |
| To R.{Sir Henry Royce} from EFC. c. RJ AYC5/T2 26.7.28. ELECTRICAL CONNECTIONS OF CUTOUT, GREEN LAMP SWITCH COIL AND GREEN LAMP. I have received your F4/M20.7.28. I think there has been a little misunderstanding of our suggested connections for these units. Our consideration of these matters from time to time always led us to the conclusion that the green lamp switch unit should be essentially a four-terminal affair - that is to say, we have thought each time that the positive supply which goes through the switch contacts to the lamp should not be identical with the positive supply going to the operating coil. Our suggestion of making the positive connection as near to the battery as possible only referred to the positive supply to the lamp (through the switch), it having been our intention that the positive supply to the operating coil should be connected either to B or to C and probably preferably to the latter. Our consideration of the matter has also led us to the conclusion that the cutout coil should on the other hand be definitely connected to C in any case, and we are pleased to note that you agree with this suggestion. You may remember that we have to some extent regarded the green lamp scheme not merely as a high voltage "switch off charge" indicator, but also to some extent as a danger unit to be so arranged as to light the lamp also when there is something wrong with the system. It was for this reason that there exists the idea of connecting the operating coil to B so that an indication would be given by the lamp | ||