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 2 of a document outlining a series of magneto testing procedures, including short circuit, open circuit, and utility tests.
| Identifier | ExFiles\Box 57\2\ Scan231 | |
| Date | 29th March 1928 guessed | |
| Contd. -2- (b) Immediately following (a) a short circuit test in which it is run at 1500 r.p.m. for half an hour with timing lever central and primary and secondary windings short circuited, i.e. with the low tension and the high tension terminal connected to the metal framework of the magneto. (c) Immediately following (b) an open circuit test at 1500 r.p.m. for quarter of an hour with timing lever fully advanced and the H.T. terminal not connected to anything, so that the secondary discharges take place on the safety gap of the magneto. (5) The magneto shall now be subjected to a utility test, i.e. a test to find out its capability of producing sparks under adverse (i.e. leaky) plug conditions. For this purpose a 3.0 mm. annular spark gap (dia. of central electrode .087", inside dia. of earthed electrode .325") in air, shunted by a constant non-inductive chemical leak of value 2.5 micromhos, shall be connected up to the H.T. terminal. The magneto shall be capable of firing this special test gap with shunted leak regularly at a speed of 300 r.p.m. retarded and at a speed of 1500 r.p.m. advanced, length of H.T. lead assumed always to be 2 ft. It would be very desirable if some means were utilised to reduce the energy of the armature at high speeds so as to prevent undue burning of the distributor points. (6) The magneto shall be capable of firing regularly in sequence a 5.0 mm. third point spark gap in air at a speed of 3500 r.p.m. in the fully advanced position. (7) The magneto shall similarly be capable of firing regularly a 5.0 mm. third point spark gap in air at speeds of :- Contd. | ||