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).
Investigating the properties and use of ballast resistance, particularly concerning nickel wire for ignition and dynamo applications.
| Identifier | WestWitteringFiles\O\2April1926-June1926\ Scan235 | |
| Date | 24th June 1926 | |
| To R.{Sir Henry Royce} From EFC. c. BJ. PN.{Mr Northey} Wor.{Arthur Wormald - General Works Manager} c. E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} EP.{G. Eric Platford - Chief Quality Engineer} c. By.{R.W. Bailey - Chief Engineer} Rg.{Mr Rowledge} ORIGINAL EFC/T24.6.26. X.8720. BALLAST RESISTANCE. x5660 x294 The rate at which the value of the resistance of the ballast resistance increases with increase of loading is a good deal smaller after it begins to be dull red, and it would appear that for ballast resistance to be used in the most effective way we must not reach the dull red condition, but rather re-arrange the length and diameter of the wire to use the same cold resistance in a more effective way. Although this feature was first thought to depend more particularly on the exact alloyed constituents of the nickel wire used, it appears now that it is more a function of the exact way in which the nickel wire is used, i.e. not run too hot at the top limit. This subject is under investigation, both from the point of view of getting the right ballast resistance for the ignition (apart from having the right amount) and also from the point of view of suitably reducing the output curve of the 20 HP. or 40/50 HP. dynamo by inserting a field resistance. In connection with this last mentioned subject, please find attached a copy of preliminary curves shewing the effect on output in a given condition of the standard 20 HP. dynamo, of the insertion of various kinds of resistance in its field winding, the one case only of 1.725 ohms being a Contd. | ||