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).
Production test specification for an ignition coil and ballast resistance.
| Identifier | ExFiles\Box 164\5\ img195 | |
| Date | 31th January 1934 | |
| SPECIFICATION NO. ELC.11. PRODUCTION TEST OF IGNITION COIL AND BALLAST RESISTANCE. (1) Continuity of primary and secondary circuits shall be tested by applying an A.C. voltage of 200 to the secondary, when a small 4 volt lamp connected across the primary should be lighted. (Care should be taken to secure a definite metallic connection to the high tension terminal of the secondary winding). (2) Now test for short circuited turns, etc. in either secondary or primary, by inserting an A.C. milliammeter in the supply circuit, when the milliamperes of current taken by the secondary winding with the primary open circuited, should not exceed the limit 15.0. (3) The high tension terminal is now connected to the central terminal of an R.R. chassis distributor, it being supposed that the distributor is already connected in sequence to six 3 point spark gaps. The primary of the coil is connected up in series with a 12 volt battery, a standard ballast resistance (35" of 32 S.W.G. nickel wire), switch, ammeter, and an RR. contact breaker with standard condenser (.21 to .25 microfarad at 18°C.) across its contact points, the make ratio of these latter being set to .55. This make ratio should be periodically checked,. A convenient way of doing this is to keep a small resistance made up non-inductively, which, when placed in circuit with the 12 volt battery, ammeter and contact breaker, just permits the passage of 1.00 ampere when the contacts are closed. The make ratio of the distributor can then be set by adjusting and locking the contact points in such a position as to permit the passage of .55 ampere with the contact breaker running at 800 r.p.m. (This averages out any slight differences in the gaps due to the six points of the cam). The test consists of a preliminary run of 5 mins. at 800 r.p.m. under above conditions, with the spark gaps set to 6.5 mm. (4) This test consists in running for 5 mins. under working conditions, i.e. on 12 volts, but with the high tension wire disconnected from the coil, i.e. with the secondary open circuited. The running current at the end of this test must not exceed 1.20 amperes. During the test, a distributor H.T. rotor may also be tested (for insulation) as described under distributor production test. | ||