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).
Analysis of voltmeter positioning and the functionality of a Danger Lamp Unit, referencing a Mentor thermal switch.
| Identifier | ExFiles\Box 59\1\ Scan161 | |
| Date | 12th October 1927 guessed | |
| -3- Contd. system when the main switch is put on, but this is of no consequence because it is only in the same street as the ignition load in this respect (if the ignition contact points 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 to which this statement is not applicable 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. EFCl/T8.4.25. 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 to operate an independent lamp, i.e. 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 the circuit between the main switch and distribution terminal A, i.e. via the ammeter, main fu battery, chassis frame, series coil of cutout, and cutout contacts. Contd. | ||