DC Generators & Motors Flashcards
DC Generator
Definition:
A DC generator is a device that converts mechanical energy into direct current (DC) electrical energy using the principles of electromagnetic induction.
Important Attributes:
Components: Armature, field windings, commutator, brushes, etc.
Operation: Relies on electromagnetic induction.
Output: Direct current.
Examples:
Hand-crank generators.
Portable DC generators used for backup power.
Non-examples:
AC generators.
Batteries.
Stator
Definition: The stator is the stationary part of an electric generator or motor that contains the field windings.
Important Attributes:
Static Part: Does not move.
Contains: Field windings or permanent magnets.
Examples:
The stationary part in a DC motor.
The housing that holds the field windings in place.
Non-examples:
Rotor.
Commutator.
Rotor
Definition: The rotor is the rotating part of an electric generator or motor.
Important Attributes:
Rotating Part: Moves within the stator.
Interaction: Induces or is induced by magnetic fields.
Examples:
The rotating shaft in a DC motor.
The armature in a DC generator.
Non-examples:
Stator.
Brushes.
Armature
Definition: The armature is the part of an electric machine that carries alternating current, typically where electromotive force (EMF) is induced.
Important Attributes:
Windings: Contains windings where voltage is induced.
Movement: Typically rotates within the magnetic field.
Examples:
The rotating coil in a DC generator.
The moving part in an electric motor.
Non-examples:
Field windings.
Stator.
Commutator
Definition: The commutator is a mechanical switch in DC machines that reverses the direction of current between the rotor and the external circuit.
Important Attributes:
Segmentation: Made of copper segments.
Function: Ensures current flows in one direction.
Examples:
The segmented ring on the armature shaft.
Part of a DC motor that interfaces with brushes.
Non-examples:
Slip rings (used in AC machines).
Stator.
What happens if you replace the slip rings in an alternator with a commutator ?
It becomes a dc generator
Brushes
Definition: Brushes are conductive carbon or graphite components that conduct current between stationary and rotating parts of a machine.
Important Attributes:
Material: Typically carbon.
Contact: Maintain contact with the commutator.
Examples:
Carbon brushes in a DC motor.
Graphite brushes in a generator.
Non-examples:
Bearings.
Insulators.
Field Windings
Definition:
Field windings are coils of wire that produce a magnetic field when an electric current flows through them.
Important Attributes:
Electromagnetism: Create a magnetic field.
Placement: Located in the stator or rotor.
Examples:
Electromagnets in a DC generator.
Coils in an electric motor.
Non-examples:
Permanent magnets.
Armature windings.
Magnet
Definition:
A magnet is a material or object that produces a magnetic field.
Important Attributes:
Poles: North and South poles.
Field: Produces a magnetic field.
Examples:
Permanent magnets in small DC motors.
Electromagnets in larger generators.
Non-examples:
Non-magnetic materials like plastic.
Electrical conductors like copper without current.
Shaft
Definition:
The shaft is a rotating component that transmits mechanical power.
Important Attributes:
Rotational Movement: Transfers rotational energy.
Connection: Connects to the rotor or armature.
Examples:
The central rod in a DC motor.
The rotating axis in a generator.
Non-examples:
Stator.
Housing.
Yoke
Definition:
The yoke is the outer frame of a machine that provides mechanical support and carries the magnetic flux.
Important Attributes:
Structure: Provides structural support.
Magnetic Path: Completes the magnetic circuit.
Examples:
The iron frame of a DC generator.
The outer casing of a motor.
Non-examples:
Rotor.
Armature.
Alternators
Definition:
An alternator is a type of generator that converts mechanical energy into alternating current (AC) electrical energy.
Important Attributes:
Output: Alternating current.
Components: Similar to DC generators but with slip rings.
Examples:
Car alternators.
Wind turbine generators.
Non-examples:
DC generators.
Batteries.
Back EMF
Definition:
Back EMF is the voltage generated by a running motor that opposes the applied voltage.
Important Attributes:
Opposition: Opposes the supplied voltage.
Dependence: Depends on motor speed.
Examples:
Voltage generated in a running DC motor.
Counter EMF in electric fans.
Non-examples:
Applied voltage.
External power supply.
Definition:
Electromagnetic induction is the process of generating an electromotive force (EMF) by changing the magnetic field.
Important Attributes:
Faraday’s Law: Governed by Faraday’s Law of Induction.
Change: Requires a changing magnetic field.
Examples:
Induction in a generator.
Transformers.
Non-examples:
Static magnetic fields.
Resistive heating.
Pole Core
Definition:
The pole core is the part of the magnetic circuit in a machine that supports the field winding.
Important Attributes:
Magnetic Path: Conducts magnetic flux.
Support: Holds the field winding.
Examples:
Iron cores in a DC motor.
Laminated cores in generators.
Non-examples:
Windings.
Commutator.
