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).
Specifications and performance requirements for a dynamo, including amperage, voltage, and physical dimensions.
| Identifier | ExFiles\Box 60\4\ Scan031 | |
| Date | 21th February 1931 | |
| Mr. Burton; Messrs. Rolls-Royce of America Inc. 21st February, 1931. -2- (5) What is the maximum ampere setting at which the machine can be run continuously in an ambient temperature of say 25 C. without overheating and either running the solder of its commutator connections or damaging its armature by charring. N.B. In putting this query to you it is necessary to specify the operating voltage. We think that this should be that for a fully charged battery in which case it may be considered to be 9.0 volts. It is noted that your ordinary load is 15 amperes and that your maximum load in an extreme case is 25 amperes. If we say that the maximum possible safe setting for all circumstances without damage to the dynamo occurring is a 20 ampere setting, then since this is a 6-volt system it corresponds to nearly 10 amperes on our 12-volt system. We have the problem of obtaining from a machine of weight less than 32 lbs, carcase diameter 5.5", armature diameter 3.5", armature active length 3.30" (approximate dimensions), a peak output continuously of 18 amperes at 18.0 volts, concurrently with an open circuit voltage of 14.0 at 700 R.P.M. (hot condition), the machine to be such that at speeds above peak output up to 4,000 R.P.M. the output does not fall away more than one or two amperes. | ||