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 fault with the green lamp operating switch in a dynamo-battery circuit during start-up.
| Identifier | WestWitteringFiles\S\March1928-May1928\ Scan062 | |
| Date | 30th March 1928 guessed | |
| --4-- Contd. For the moment we are connecting the negative end of the green lamp switch operating coil to earth, though this is not as described sometime ago in our EFCL/T25.10.27 in the section entitled "Danger Lamp Unit". It will thus include no more portions of the dynamo-battery circuit in its warning indications than the auto charge control switch includes in its protections. The reason of this is that it has occurred to us that this green lamp operating switch may suffer from the same fault as the auto charge control switch when we had its negative end connected on the other side of the cutout, i.e. when the coil was connected across the dynamo terminals. The switching on of the dynamo when running at a fair speed, or sudden acceleration of the dynamo with the charging switch on, causes a rapid rise of excitation which operated the auto switch and caused it to go over before the cutout had time to close. There is a possibility that the same thing may happen with the green lamp switch unit, and that therefore the green lamp may be lighted - asking for the charge to be switched off - when first starting up. We have the first green lamp switch unit on test and I am just informed that this does happen. We shall make further tests to see if it can be prevented (it is just a question of whether the de-operating voltage of the switch can be brought sufficiently near the operating voltage, so that the switch can return to the "off" position on the normal system voltage before the battery has risen to its final kick-up). In the meanwhile we are Contd. | ||