The Elementary Generator

Author: E.E. Kimberly

Fig. 10-4 shows an elemental generator in which two conductors with a back connector form a loop terminating at the two segments of a reversing switch or commutator. When the conductors reach a position a midway between the pole tips, they will cut no flux and hence generate no electromotive force.

Fig. 10-4. Elementary Generator

At that same instant,each of the brushes which connect the loop to the outside circuit will change contact from one commutator segment to the opposite segment, thus reversing the connection of the coil to the outside circuit. Inasmuch as the direction of the electromotive force generated by each conductor as it re-enters the magnetic field will be opposite to the direction it had before the midpoint was reached, the direction of the electromotive force at the brushes relative to the outside circuit will be the same as before. Hence, the voltage appearing at the terminals of the generator will be approximately as shown in Fig. 10-5.

Fig. 10-5. Voltage in Direct-Current Generator