Difference Between Amperage And Voltage
The power of an electric current is the amount of work it can do. This power depends on two things: amperage and voltage. Amperage is the measurement of how much current is moving through the wire. Voltage is the measurement of the force that is pushing the current through the wires. Three things determine the voltage a generator will produce:
(1) The strength of the magnetic field. The stronger the field, the greater the voltage.
(2) The number of coils of wire in the armature. The greater the number of coils in the armature, the greater the voltage.
(3) The speed of rotation. The faster the generator turns, the greater the voltage.
These principles are used in designing generators. Almost all generators have more than one magnet to make the field stronger. In addition, most generators use electromagnets instead of permanent magnets. This is because electromagnets can be made stronger than permanent magnets. Most electromagnets consist of a coil of wire wound around an iron core. An electric current running through the coil produces a magnetic field. The iron core concentrates (strengthens) the magnetic field. The iron core is magnetized only as long as the current is flowing through the coil.
Some generators use permanent magnets. These are magnets that keep their strength for long periods of time. Generators that use such magnets are sometimes called magnetos.
A small DC generator can be used to supply current for the electromagnets of a whole series of large generators. (Power stations today usually have one small DC generator for each big AC generator.)
Generators for actual use are built with many coils in the armature. In many AC generators, especially the larger ones, the armature coils remain still and are arranged around the outside of rotating electromagnets. That is, the magnetic field moves instead of the armature coil.
This arrangement works well if a generator has a high-voltage armature. (In such a generator, the voltage used for the electromagnets is much lower.) Moving the magnetic field makes it unnecessary to pass high-voltage current from a moving armature through the brushes and slip ring. Thus it helps prevent harmful sparking and overheating. It is easier to use slip rings for the low-voltage electromagnets and a permanent connection for the high-voltage armature.