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).
Report comparing performance curves and electrical measurements for a dynamo or shunt machine.
| Identifier | WestWitteringFiles\C\May1919\ Scan50 | |
| Date | 7th May 1919 | |
| R.R. 235A (500 T) (S.D. 408. 26-4-17.) Bm. 2/156/13. Contd. -7- EFCl/T7.5.19. supplied with the Lucas switchboard has gone or been removed. The cutting-in speed is very much later. The current is smaller at first, but the point to be noted is that it is considerably greater than normal currents at high speeds. At the point X where it crosses curve (c) at a speed of 2200 R.P.M. the two currents are the same, this agreeing with the curves for six cells on sheet D, where as previously stated, it will be found that the main current plus the field current is equal to the control current at a speed of about 2200 R.P.M. Curve (e) gives the performance as a plain shunt machine, using the control brush as the negative brush. COMPARISON OF RESULTS OF CURVES A & D.{John DeLooze - Company Secretary} At 1500 R.P.M. the field current is 2.18 amperes, main voltage 16.1. Open circuit voltage with same excitation, from curves (A) equals 30.5. Similar figures for a speed of 2500 R.P. are 2.15 amperes field current, main voltage 16.2, open circuit voltage at this field current 50.5 volts. These figures give us an idea of the losses due to armature re-action and may be compared with similar figures given for the C.A.V. dynamo, they are not quite as bad as those, however. Further investigations are being carried out in connection with the cut-out and with the reason of the particular position of the fuse in the various circuits. These will be reported upon separately. EFC. | ||