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).
The design and application of a 'Danger lamp unit' for vehicle electrical systems.
| Identifier | WestWitteringFiles\R\2October1927-November-1927\ 43 | |
| Date | 18th April 1925 | |
| -4- happen to be on contact). It makes a connection between the dynamo windings and the frame when both switch and cutout are off contact, and therefore prevents a high voltage insulation test of the dynamo to earth being taken, unless the wire is removed from one terminal of the voltmeter. This is considered to be of no practical consequence. An alternative position of the voltmeter would require an independent voltmeter switch. (2) Danger lamp unit. (One unit of human element). The reason we give this title to this unit is because (a) On the diagram, at any rate, it is intended to represent not only an electro-magnetic relay, but also a thermal relay of the Mentor type, in which case the coil shown must be considered to be a heater. The functioning of the Mentor thermal switch unit has been described by us in a previous report, ref. EFC1/18.4.25 Unfortunately the lamp fitting of this mentor unit was unsatisfactory though, as far as we can judge, the operation of the contacts was reasonably satisfactory, and there would appear no reason why a further experiment should not be made in which it should be made to operate an independent lamp, .e.g. the high water temperature indicator lamp. (b) We are conceiving it as being applied to the red lamp already in existence on the cars as a high water temperature indicator. (c) Connected in the way we are showing it is not merely a high voltage indicator, but also an indicator that the system is in danger, e.g. when there is a broken dynamo battery circuit, anywhere on the battery side of thee circuit between the main switch and distribution terminal A, i.e. via the ammeter, main fuse, battery, chassis frame, series coil of cutout, and cutout contacts. We have carefully considered as to whether this unit should be made with three or with four terminals. Contd. | ||