Series Generator

Chapter 7.7 Series Generator

Fundamental Electrical and Electronic Principles Third Edition Book
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Fundamental Electrical and Electronic Principles Third Edition Book

  • 242Fundamental Electrical and Electronic Principles The shunt generator is the most commonly used d.c. generator, since it provides a reasonably constant output voltage over its normal operating range. Its other obvious advantage is the fact that it is self-exciting, and therefore requires only some mechanical means of driving the armature. 7.7 Series Generator In this machine the fi eld winding is connected in series with the armature winding and the load, as shown in Fig. 7.15 . In this case, IL Ia If , so this is a variable-fl ux machine. Since the fi eld winding must be capable of carrying the full-load current (which could be in hundreds of amps for a large machine), it is usually made from a few turns of heavy gauge wire or even copper strip. This also has the advantage of offering a very low resistance. This generator is a self-excited machine, provided that it is connected to a load when started. Note that a shunt generator will self-excite only when disconnectedfrom its load. When the load on a series generator is increased, the fl ux produced will increase, in almost direct proportion. The generated emf will therefore voltageEV0ILIaRafull-load Fig. 7.14 IaRaRLILRfIfIaIfILVE Fig. 7.15