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).
Continuation of a report detailing results and observations from electrical charging tests on a valve.
| Identifier | ExFiles\Box 32\5\ Scan021 | |
| Date | 24th December 1925 guessed | |
| -2- Contd. Next the swivelling link was thrown over as recommended for charging from five up to seven cells. This automatically puts one of the resistances out of action. Results in this condition were as follows :- No. of cells. Volts. D.C. amps. A.C. amps. 4 9.1 3.15 1.12 5 11.3 3.10 1.15 6 13.6 2.05 1.1 7 15.5 2.65 1.05 The Royce ammeter was used in all cases for measuring A.C. amperes. Assuming a constant power factor in the A.C. supply, the highest efficiency is obtained when charging four cells through both resistances and the lowest when charging one cell through one resistance. Taking unity power factor these efficiencies would be 33-1/3% and 4-1/2%, respectively. When lighted a horizontal coil filament can be seen inside the valve, with a plate on either side lying (though not very accurately) in planes parallel with it. Apparently when the filament reaches a certain temperature, arcs are automatically struck between the filament and each plate, the latter being connected, one with each resistance and dealing one with each half wave of the alternating current. Hence the valve is provided with four terminals. When one resistance lamp is removed, the glow inside the valve diminishes because one arc is extinguished. There is no glow on open circuit because neither arc is struck. When charging, local scintillations can be seen at the filament. On re-inserting a resistance after removal, bright flashing occurs as on starting up. Throwing over the swivelling link evidently has some other effect than merely putting one resistance into or out of circuit as the effect is quite different from that of removing one resistance. Compare 4-cell charging under the two conditions. EFC/RJA. | ||