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).
Page detailing the methodology for comparative heating tests on various dynamos.
| Identifier | WestWitteringFiles\F\January1921\ Scan19 | |
| Date | 11th January 1921 | |
| Contd. -2- EFC3/T11.1.21. HEATING TESTS. The open circuit volt-speed curves cold and hot and the ampere-speed curves cold and hot do not define the electrical performance of a machine completely, but it is necessary also to make comparative heating tests. For this purpose two definite outputs were fixed upon; first, 9 amps. at 14.6 volts and secondly 12 amperes at 15.0 volts. Each machine was run in the first instance starting from cold and made to give a constant output of the first amount, the operating voltage being controlled to exactitude by means of a low variable carbon resistance in series with the battery, the amperes being controlled in the usual way by regulating the speed of the driving motor. The plotted curves, of which there are two sheets (one for Bosch, Bijur and Rotax, and one for Smith A, Smith 2D and Westinghouse) give the variation of three items on a time base for each machine. The three items are respectively - 1. Temperature of carcase by thermometer. 2. " estimated from rise of field coil resistance. 3. Dynamo speed which naturally has to increase as the machine warms up to maintain the same output. The output of those dynamos which attained a final temperature condition at this output which was not excessive, was then increased to the larger output of 12 amps. at 15.0 volts, and the heating test carried on. This change of output conditions is shown on the curves by a sudden rise | ||