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 and inspection procedure for a ballast resistance used in an ignition coil.
| Identifier | ExFiles\Box 168a\5\ img042 | |
| Date | 13th February 1929 | |
| X.7781b. X.5781b. PRODUCTION TEST & INSPECTION OF BALLAST RESISTANCE (1-3/4 VALUE) FOR IGNITION COIL. X.7720 X.5720 (35 inches of 32 S.W.G. NI Wire.) A rig should be used with connecting pins, on which three ballast resistances can easily be placed. The rig should contain a suitable switching arrangement to enable these resistances to be placed on first in series and then in parallel. (1) Inspection shall be made of the resistance coil turns that they are all spaced equidistantly and not making contact, i.e. short circuiting some of the turns. (2) The terminals of the arrangement should be connected through an ammeter to a 12 volt battery. Firstly, with the switch in the series position, voltmeter readings across each of the three ballast resistances should be taken in turn, and should lie between the limits 3.5 and 4.5. (3) Then the switch should be placed in the parallel position and the ballast resistances allowed to be warmed up for 8 minutes, during the last minute of which the current taken by the three in parallel shall fall within the limits 6.2 to 7.2 amperes. (4) Now reduce the voltage to 6, and after 5 minutes the current should fall between the limits 4.8 and 5.8 amperes. (5) Finally examine the connections of the ballast wire ends on the tags and ascertain by gentle trial that no weakness has been caused where the two working ends of the wire pass away from the joints. The porcelain also should be gently tapped to enable any possible cracks to assert themselves. Further, see that the brass ferrules are not loose and liable to get twisted round. EFC. | ||