
ELECTRICAL SYSTEM 481
charging system when the engine is running and always
ensuring correct polarity when connecting a battery or
booster battery.
Advantages of the alternator
As compared with the earlier dynamo, the advantages
of using an alternator can now be summarized as
follows:
1 The alternator can be operated at much higher
speeds, because it is not limited by commutation
problems and undesirable centrifugal effects on
armature coils. In being driven faster it can therefore
charge the battery even at engine idling speed.
2 An alternator with three-phase stator coils and built-
in diode rectifier has a much superior output-to-
weight ratio ...