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).
Instructions for diagnosing electrical faults in the charging system using a voltmeter.
| Identifier | ExFiles\Box 70\3\ scan0312 | |
| Date | 16th September 1927 guessed | |
| -3- Contd. This assumes engine to be running on magneto only. (12) In the same circumstances of charging on the peak with the side lights only switched on, do these appear to be excessively bright ? (13) Have lamp bulbs unexpectedly been burnt out ? while charging on the peak A test of the system might be made with a sensitive moving coil voltmeter with a 20 or 30 volt range. The negative end of the voltmeter should be connected to the chassis frame and voltage readings should be taken at the following points :- (a) Positive terminal of battery. (b) Main battery emergency fuse wire. (c) The top clip of No.6 fuse. (d) The top clip of No.1 fuse. (e) The top clip of No.2 fuse. (f) The dynamo terminal B. (g) " " C. (h) " " A.{Mr Adams} In this case the voltage indicated should be <strikethrough>negligible</strikethrough> negative (about 1/2 volt) so that to read it accurately, connections to the instrument will have to be reversed. (i) The fixed contact support of the cutout. This is also negative and the same applies as in (h). (j) The moving lever of the cutout. This again is negative, but of a still smaller amount than (h) and (i). It is assumed that while taking the above readings, the dynamo speed is maintained with the charging rate steadily on the peak of output. Readings would of course vary if the ampere-output of the machine varies either due to a variation of speed or rise of battery voltage. They should be taken as far as possible therefore with the battery fully charged. To avoid running the system in a wrong condition, likely to damage the dynamo, it should first be noted that the terminal potential difference between terminals A and B of the dynamo does not exceed 19.0 volts which is 1 volt over and above the maximum possible voltage, viz. 18.0 which can occur in normal working, but would not be sufficiently high to allow damage to the machine during the comparatively short period in which these readings are taken. Contd. | ||