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).
Proposed modification to a green lamp indicator circuit for improved system protection.
| Identifier | WestWitteringFiles\S\March1928-May1928\ Scan005 | |
| Date | 7th March 1928 guessed | |
| -2- Contd. have now (only comparatively recently) been returned from customers with armature contacts badly burnt through the armature breaking first, we think that this slight modification should be adopted as standard forthwith. Returning to the green lamp scheme, it is to be noted that when the green lamp lights up and the charging switch is put off, the green lamp goes out unless the shunt swi coil of its operating switch unit is connected like the auto switch shunt coil and (also) the charge is switched off by an additional field switch. There is no indication as to when to put the charge on again, but connected and arranged as described, the green lamp could remain on. A further point to note is that in view of the fact of working through the human element, the green lamp scheme does not give the instantaneous protection to the system necessary to prevent the lamps being burnt out if the battery circuit becomes broken. On the other hand, the green lamp scheme, connected in a way differing from that of the auto switch, offers the possibility of including in its indications of broken dynamo-battery circuit, that portion of the circuit through the cutout contacts, i.e. anywhere except the portion between distribution box negative terminal A and the surface of the dynamo commutator under the negative brush. It can give warning of break anywhere, i.e. inclusive of the negative brush to commutator connection, if the operating coil of the green lamp switch be connected as a shunt across the field coil of the dynamo, but this would require the complication of the provision of an extra terminal and wire. EFC. | ||