ENERGY CONVERSION/MOTORS/GENERATORS Flashcards
equivalent of or capacity of doing work
Energy
transformation of energy from one form to another. Energy in the forms provided by nature that can be used such as electricity.
Energy conversion
Two General Methods of Energy Conversions
- Direct Energy Conversion
- Dynamic Energy Conversion
Static without mechanical motion
Direct energy conversion
With Mechanical Motion
Dynamic energy conversion
somestimes called static energy-conversion devices. Most of these energy converters use electrons as their working fluid.
Direct energy-conversion devices
changes chemical energy directly into an electric current.
Electrochemical Cell
converts sun light into electricity
Solar cell
drives electrons across a potential difference at a semiconductor juction.
Radiant energy
used junctions formed by coating selenium (a semiconductor) with an extremely thin layer of gold.
Genuine solar cell
is often used interchangeably with photovoltaic cell, photocell, or photoelectric cell.
Solar cell
(seedback effect) are devices that convert heat directly into electricity.
Thermoelectric generators
generated when electrons are driven by thermal energy across a potential difference at the junction of two conductors made of dissimilar materials.
Electric current
junction of two conductors made of dissimilar materials.
Thermocouple
generate electricity when subjected to mechanical pressure.
Piezoelectric devices
electrochemical producer of electricity. continuous operations is achved by feeding fuel(hydrogen) and an oxidizer(oxygen) to the cell and removing the reaction products.
Fuel cell
direct energy converter with considerble potential. produces electricity directly from a high temperature, high pressure electrically conductive fluid (usually an ionized gas) moving through a strong magnetic field.
Magnetohydrodynamic
the terminal voltage of the battery with no load connection.
Open circuit voltage
the terminal voltage of the battery with load connection.
Operating voltage
the capacity of the battery which tells us how long the battery can supply a given load.
Ampere hour
when batteries are kept, the length of time under a specified condition that the battery retains its usability.
Shell life
cell cannot be recharged, cannot restore chemical reaction, whose chemical reaction is not reversible.
Primary cell
cell that can be recharged, can restore chemical reaction, whose chemical reaction is reversible.
Secondary cell
cell that have a very long shelf life.
Reserve cell or battery
mechanical rotating machine that converts mechanical energy to electrical energy or vice versa.
Dynamo
reversible machine can be used as a motor or generator.
Gamme dynamo
Battery Ratings
*Open Circuit Voltage
*Operating Voltage
*Ampere-hour
*Shelf life
DYNAMIC ENERGY CONVERSION-DEVICES
*Electrical Machines
*Generators
*Motors
*Rotary Converters
*Frequency Converter
refer to rotating machines that convert energy from one form to another.
Electrical machines
convert mechanical to electrical energy.
Generators
convert electrical to mechanical energy.
Motors
convert ac voltage to dc voltage, or vice versa.
Rotary converters
convert ac voltage at one frequency to another ac voltage at another frequency.
Frequency converter
Parts of Generators
*Prime Mover
*Output Voltage
the source of mechanical power energy used to turn the rotor of the generator.
Prime mover
the output electrical energy that is the result of rotating the rotor of the generator.
Output voltage
TWO IMPORTANT PARTS OF A GENERATOR
*Field poles
*Armature winding
even sets electromagnets or permanent magnets. Thi provides excitation or flux to the armature.
Field poles
a laminated core with current-carrying copper wires. This will cut the flux supplied by the field poles.
Armature winding
Dc generators
*Self-Eited Shunt Generator
*separately exited shunt generator
*Series Generators
*Compound Generators
Short and long shunt compound generators
is the most important means of producing electrical power.
Ac generator
Regardless of the size of ac generator they have two mechanical parts
*rotor
*stator
is the part that rotates
Rotor
is the part that remains stationary
Stator
armature is always the rotor
Dc generator
the armature may be either rotor or stator
Alternators
TYPES OF ALTERNATORS
- Rotating-armature alternator
- Rotating-field alternator
This alternator is similar in construction to the dc generator in that he armature rotates in a stationary magnetic field.
ROTATING-ARMATURE ALTERNATOR
The EMF generated in the armature windings converted from ac to dc means of the commutator.
DC GENERATOR
The generated ac is brought to the load uncharged by means of slip rings. Generally not used to supply electric power in large quantities.
-ROTATING-ARMATURE ALTERNATOR
The advantage of having a stationary armature winding is that the generated voltage can be connected directly to the load. A rotating armature requires slip rings and brushes to conduct the current from the armature to the load.
-ROTATING FIELD ALTERNATOR
The prime movers is the source of the mechanical power that is required to turn the rotors of all generators, large or small, ac or dc.
-PRIME MOVERS
The prime movers are divided into two classes of generators.
-HIGH SPEED AND LOW SPEED
Examples of this prime movers are steam and gas turbine.
-HIGH SPEED
Internal-combustion engines and electric motors are classified as one of the generators in prime movers.
-LOW SPEED
In rotating field alternators
-ROTORS
There are two types of rotors
- TURBINE DRIVEN ROTOR
- SALIENT-POLE ROTOR
Has winding that are arranged to form two or four distinct poles. These windings are firmly embeded in slots to withstand the tremendous centrifugal forces encountered at high speeds.
-TURBINE-DRIVEN ROTOR
Is used in low speed alternators it consists often of several separately wound pole pieces bolted to the frame of the rotor.
-SALIENT-POLE ROTOR
Two essential parts in rotating generators
- PERMANENT MAGNETS
- ARMATURE WINDING
The voltage generated at the armature winding is always ac.
-ELECTRICAL MACHINES
Alternating EMF at the armature winding is converted to DC by the commutator.
-DC GENERATOR
The armature winding is rotated with respect to a stationary magnetic field produced by electromagnets or permanent magnets.
-DC GENERATORS
The electromagnets or permanent magnets (magnetic fields) are rotated with respect to the stationary armature winding.
-AC GENERATORS