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).
Specifications for the operation of a main switch and associated electrical circuits.
| Identifier | ExFiles\Box 64\3\ scan0107 | |
| Date | 1st February 1927 guessed | |
| -3- Contd. (a) The main switch must be definitely operated from the "off" position by a current of 2.2 amperes. (b) The current must be capable of being broken reasonably sparklessly. (c) When the main switch is operated, the main motor current is switched on and it must be considered that the available voltage drops to 9. The available amperes through the coil will then be 2.2. It is necessary therefore that the main switch be capable of definitely holding on with a pressure of 2 lbs. on the contacts with a current of 2.0 amperes through its coils. Circuit 3. (MAIN). Black. The resistances of this circuit are as follows :- The heavy current coil on relay switch. .001 ohm. Motor main field .0145 " Motor armature. .012 " AT 9 VOLTS. Total. .0275 " Upon this main circuit being switched on, it is considered that the available voltage has dropped to 9. The initial ampere rush will therefore be 327.5 and the conditions for correct operation will be :- (a) The relay switch must be definitely pulled over by a current through its heavy current winding of 200 amperes. (b) The main contacts of the main switch must carry a current of 250 amperes for one minute without shewing signs of distress. Contd. | ||