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).
Faulty ballast resistance on chassis 101-UF and experiments on new nickel fuse wires.
| Identifier | ExFiles\Box 69\1\ scan0245 | |
| Date | 22th October 1929 | |
| X.8710. Ey. from EFC. c. Ry/RD. c. Hm{Capt. W. Hallam - Head Repairs}/AVS. EFC3/AD22.10.29. CHASSIS 101-UF. In further answer to your Ry10/GS.10.29, we have now received and examined the ballast resistance from this car. we found this to be of the old single type of cold resistance .84 ohm in place of 1.50 ohm as now standard (1½ type). Also we found it to show evidence of heating on over voltage. We do not consider that the fact of its being a single ballast is alone sufficient to explain the charring of the ignition coil primary, but that it materially contributed to the charring effect due to the over voltage of the system. The fact (of the single ballast) makes it more readily understandable how the primary could be charred by a voltage of the system which did not result in the blowing of the field fuse. You will be interested to know that we are now making experiments on fuse wires of nickel in place of copper, to narrow down the range between immediate and ultimate fusing currents, the latter being determined by the magnitude of the first oxidising current which should be relatively greater in the case of nickel. Our present field fuse, to be safe in normal working, as already pointed out, may permit of double normal voltage for a considerable period before it relieves the situation. This is mentioned in the Instruction Book. We have replaced this ballast in the Repair Dept. with a standard 1½ ballast which we had available. EFC. | ||