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).
Procedure for running and insulation tests on a dynamo, including bedding of brushes.
| Identifier | ExFiles\Box 163\6\ img258 | |
| Date | 2nd February 1933 guessed | |
| -2- (f) The initial bedding of the brush shows partial contact reasonably well distributed over the working surface. (Preliminary bedding of brushes). (2) The insulation resistance of the machine should be taken and should not be less than 1 megohm. RUNNING TESTS. N.B. For the running tests of the dynamo there must be no armature end play. It may be necessary to insert washers between the temporary driving pulley and the pulley end bearing so as to keep the armature up towards this bearing, i.e. in the position which it will have when fitted on the chassis. (1) The dynamo shall now be run on load and the brushes bedded until each shows evidence of making contact over the whole of its surface. (2) In order to bring the machine to its working temperature, and to get the brushes finally bedded and the commutator surface with its working skin formed, the machine should be run with the end cover off for 3 1/2 hrs. at about 2050 R.P.M. During this run the dynamo terminal voltage should be 17.5 + .5 volts. (3) At the end of the above run the output of the machine should fall within the limits 15.5 and 16.5 amperes at 2050 R.P.M. with the voltage adjusted to 17.5 +/- .1. If necessary the control brush should be adjusted to bring the output within these limits. (4) With the dynamo still hot it should show an open-circuit voltage of 14.0 at not more than 910 R.P.M. (5) Now run the machine at varying speeds up to 4000 R.P.M. and observe that noise, brush sparking and mechanical balance are reasonable. Afterwards confirm the condition of the machine by general inspection. INSULATION. While still warm, apply an alternating voltage of 200 through a low c.p. lamp between terminals and case and confirm that no failure of the insulation occurs. | ||