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).
Experiment testing the use of ballast resistance in place of a fuse in constant current generators.
| Identifier | WestWitteringFiles\D\January1920\ Scan42 | |
| Date | 21th January 1920 | |
| To R.{Sir Henry Royce} from Ck.{Mr Clark} c. to CJ. c. to Bn.{W.O. Bentley / Mr Barrington} c. to OY. ORIGINAL Ck{Mr Clark}9/T21.1.20. X.294. - CONSTANT CURRENT GENERATORS. X.3716. Use of Ballast Resistance in place of Fuse. X.3014b. Referring to Mr.Olley's note Oy7/G6.12.12.19, in which the use of a ballast resistance in place of a fuse in the field circuit of an inherently controlled constant current dynamo was suggested, we have tried out this idea on our standard Lucas E.575 dynamo, but do not find this to be very satisfactory in bringing about the desired end. Owing to the exciting action of the control winding of this dynamo and the action of the control current in the armature itself, the open circuit voltage of the machine is very little reduced by the inseration of ball- ast resistance in the field circuit, in fact the open circuit voltage of the machine is still quite high, even though the field circuit be broken altogether. The following experimental figures illustrate the matter:- Dynamo Speed. = 2000 R.P.M. Condition. Field Amps. Control Amps. Voltage. No additional resistance in field circuit. 5.7 24.0 50 40" of No. 30 SWG. nickel wire ballast resistance in series with field winding. 3.1 21.0 49 Field circuit broken altogether. 0 10.0 34 R.R. 285A (100 T) (S H.{Arthur M. Hanbury - Head Complaints} 159. 11-8-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2800 | ||