Alternators/Generators/Magnetism
MMG output is?
115/220v 400 hz 3 phase.
MMG Input is ?
220/440v 60 hz 3 phase
Requirements Electric Motors
MAC Magnetic Field, Applied AC, Conductor
Requirements for a Generator
MR.C Magnetic Field, Relative Motion, conductor
Purpose of the Generator
Mechanical -> Electrical energy
Rotating armature alternators
Armature will rotate in the stationary field, low power rating, armature is located in the rotor, when rotor cuts lines of flux voltage is induced.
Voltage Development
As the magnetic field cuts across the stator winding emf voltage is induced across it.
Regulator
Automatically varies the strength of the magnetic field current to maintain voltage.
Components of the DC generator
BRRC Brush assemblies, Rectifier, Regulator, Commutator
Exciter Generator
Brushless, rotating field, stationary armature.
1 Hertz =
One cycle per second.
Armature
Part of the alternator in which voltage is induced.
Primary and secondary Transformer coils do what?
Primary- Input from AC source sets up a magnetic field. Secondary - Output to load that induces voltage.
Power transformer
Provide multiple output voltages from a single input voltage
What does a transformer coil do? And different types
Provides a path for magnetic lines of force. Air/ Coil
Rotating Magnetic Field
Rotates electrically with the stator, The number of pole pairs must be the same or a multiple of the phases of current applied
Rotor
Rotating part of the alternator
Cage Rotor
Self starting
Stator
Stationary part of the alternator, consists of a laminated iron core with windings wound in it.
Brush assemblies
Stationary, spring loaded carbon brushes that provide electrical contact from slip ring to field coils.
Commutator
Takes place of the slip rings, Used only with DC voltage
Excitation
The magnetic field is set up by applying DC voltage to the rotor field, or by the use of permanent magenets.
Poly Phase
The more load the more slip. Cage rotor is most commonly used.
Frequency
The number of cycles of AC produced by the alternator each second. Measured in Hertz.
Phases
The output of each armature winding of an alternator. Output of one winding equals one phase.
Field
The part of the alternator which produces the magnetic field. Magnetic field is generated by either applying DC voltage or by the use of permanent magnets. Also called excitation.
Transformer
Transfers energy from one circuit to another through electromagnetic induction.
Single Split Phase motor
Has 1 phase, Centrifical switch that shuts off the aux winding at 75%
Rotating field armatures
Has a stationary armature, and rotating field winding, generated voltage can be connected directly to the load.
Purpose of the MMG
Used in ground maintainence, calibration, and support of aircraft where engine driven equipment is not practical.
Rectifier
Used when DC power is required, Changes AC to DC through 3 pairs of diodes. It is connected to the stator.
Instrument
Used where high voltage and current is to be measured.
Two Types of Rotors
Wire wound, cage.
Synchronous motor
Working together, Made with DC voltage at 95% on wire wound rotor. Excitation. Must use wire wound rotor.
Wire Wound rotor
frequently started and stopped,
i hate in docs i hope they all die also ram rod is a bitch
increases voltage
Step down
Decrease Voltage
Components of AC generator
FARS Field, armature, Stator, Rotor,
Components of an electric motor
Frame, rotor and stator, Stator is the stationary part of the motor
In a 3 phase alternator
the windings are 120 degrees apart.