An alternator is an electrical generator that converts mechanical energy into electrical energy. It is commonly used in vehicles, power plants, and various other applications to produce alternating current (AC). One specific type of alternator is the "Revolving Field Type Alternator."
The revolving field type alternator is a design where the magnetic field is stationary, and the conductor windings rotate within this field to generate electricity. Here's a basic overview of how it works:
Field Windings: The stationary part of the alternator contains the field windings, which are typically wound around the rotor (the rotating part) or placed in a rotor attached to the main shaft. The field windings are connected to a DC power source (usually through slip rings) to create a magnetic field when current flows through them.
Rotor: The rotor is mounted on a shaft that can rotate. It is positioned within the magnetic field produced by the field windings. As the rotor spins, it carries the conductor windings with it.
Conductor Windings: The conductor windings are wound around the rotor or attached to it. These windings cut through the magnetic lines of flux produced by the stationary field windings as the rotor rotates. This cutting of magnetic lines induces an electromotive force (EMF) in the conductor windings, according to Faraday's law of electromagnetic induction.
Output Terminals: The induced EMF in the conductor windings results in an alternating current (AC) output. The AC voltage generated is then collected and brought out through slip rings or a similar arrangement, allowing it to be used for various applications.
Advantages of the revolving field type alternator include:
Simplicity in design and construction.
Durability and reliability, as the rotating parts are often more robust than the stationary parts.
Efficiency due to the ease of maintaining the field windings and the lack of complex components like brushes and commutators.
Flexibility in terms of voltage and current output control by adjusting the field current.
However, this type of alternator also has some limitations:
It might require external sources of DC power (usually from batteries or rectifiers) to energize the field windings initially.
Regulation of the output voltage might be a bit more complex compared to other alternator designs.
Revolving field type alternators have been widely used in various applications, including automotive alternators in older vehicles, power generation in small-scale systems, and in some older power plants. More modern alternators, especially those used in most vehicles today, often use a "revolving armature" design, where the armature (conductor windings) is the rotating part and the field windings are stationary. This design offers certain advantages in terms of efficiency and voltage regulation.