GB203365A - Improvements in and relating to the generators of electric lighting sets for motor vehicles and the like - Google Patents

Abstract

203,365. Nicholas, W. J., and Roberts, P. J. W. May 3, 1922. Pole-pieces; cores; coils; exciting.-To prevent the production of high voltages and excessive currents at high speeds in a vehicle or like generator, recesses b<2>, Fig. 3, are formed in the main pole-pieces B, and auxiliary poles D are located in the recesses. The series coil E is wound to give an opposite polarity to the surrounding main pole, so that the field is weakened as the speed rises. Fig. 1. shows a circuit in normal operation, comprising a generator G having shunt and series field windings C, E, a main automatic control switch K, and an auxiliary automatic switch M, and an external circuit J. If a break occur in the battery circuit during charging, the voltage will rise, and this rise will not be wholly compensated by the winding E. The increased voltage causes a larger current to flow through the shunt coil m<2> on the switch M, and the switch closes, so that the armature is short-circuited through the coil m<1>. The series coil k<2> on the main control switch K is de-energized and the spring k' causes the switch to open, thus breaking the shunt field circuit. When the generator current ceases, switch M is opened by the spring m<3> so that the generator is again ready for operation. The shunt field is excited at starting by the battery H. The Provisional Specification describes the use of the auxiliary switch for disconnecting the battery at the peak of the charging current, and also the arrangement of the exciting windings so that change in the direction of rotation of the armature does not affect their action. Specification 191,782 is referred to.