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 modification of a Bijur dynamo for Mr. Royce, adjusting it from 6 to 12 volts by adding resistances.
| Identifier | ExFiles\Box 38\3\ Scan014 | |
| Date | 14th May 1918 | |
| H.R. 285A (100.T) (T.O. 642, 18-2-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2618 X.3360 To R.{Sir Henry Royce} from EFC. c. CJ. X.3231. RE BIJUR DYNAMO FOR Mr. ROYCE X.3362. X.3560. We shall be sending down with 49-GB the Bijur dynamo from the Packard car, adjusted to operate at 12 volts. We have made the necessary resistances and made these up into a little bundle clamped on to the side of the regulator box. We attach a photostat showing connections of this dynamo and regulator including the resistances which we have added. It will be seen that we have added 25 ohms in series with the two shunt operating coils in parallel this resistance being of such a value as to cause these coils to receive about the same current at 12 volts as they originally received at 6. We have also considered it necessary to add resistances in series with the original (A) resistance of 29 ohms, and (B) resistance of 20 ohms, of amounts suitable for reducing the currents through these to their normal values. We find if we do not add these, the resistances get very hot and as we think, too hot. As regards the field winding of the dynamo we have not considered it necessary to add resistance in this winding, because with the dynamo normally running at 1400 R.P.M. to 1500 R.P.M. the fields need only receive running at half this speed to produce 6. We have run this dynamo set up with these resistances for a considerable period and we found that the heating is perfectly reasonable. We do not find on the whole that the | ||