The higher voltages generated by alternators enables the transmission of electrical energy to vastly greater distances than possible by a direct current system, so that the energy from many waterfalls that otherwise would go to waste may be utilized.
Classes of Alternator.—There are various ways of classifying alternators. They may be divided into groups, according to: 1, the nature of the current produced; 2, type of drive; 3, method of construction; 4, field excitation; 5, service requirements, etc.
From these several points of view, alternators then may be classified:
1. With respect to the current, as:
- a. Single phase;
- b. Polyphase.
2. With respect to the type of drive, as:
- a. Belt or chain driven;
- b. Direct connected.
3. With respect to construction, as:
- a. Revolving armature;
- b. Revolving field;
- c. Inductor.
- Homopolar and heteropolar.