Download Electrical Components

Lesson 9: Electrical
Components
Batteries
• A device composed of one or more cells in which
chemical energy is converted into electrical energy.
• The most commonly used storage battery for
aircraft is the lead-acid battery.
Batteries
• Lead-acid Batteries
• Used for Starting engines and supplying power
in the event of generator failure.
• Stabilize and smooth out the generator output
during extreme load changes.
• 12 volt or 24 volt batteries are available.
Batteries
• Battery Ratings
• Voltage
– Voltage of any battery is always a function
of its state of charge and current load
placed on the battery.
– The number of cells in a battery determines
the voltage it will produce.
Batteries
• Battery Ratings
• Ampere-hour Capacity
– The area of the plates, the amount of active
material in the plates, and the amount of
electrolyte determine the ampere-hour
capacity of the battery.
– The capacity is a measure of the battery’s
ability to produce a current flow for a
specified time.
Batteries
• Ampere-hour
• One ampere-hour of capacity is the amount of
electricity that is put into or taken from a
battery when a current of one ampere flows for
one hour.
• Any combination of flow and time that moves
the same amount of electricity is also one
ampere-hour.
Batteries
• Rated capacity
• Indicates the battery’s ability to perform when
it is new.
What determines the battery’s actual capacity?
Batteries
• Actual capacity depends on:
• Battery temperature
• Battery state of charge
• Battery condition
Generators
AC Generator
AC Generator
DC Generator
DC Generator
DC Generator
DC Generator
DC Generator
• Disadvantages
• All of the AC load current is produced in the
rotating armature of a generator.
• The AC must be changed into DC by the
commutator and brush assembly.
• The brushes and commutator typically require
regular maintenance.
DC Alternators
DC Alternators
• Generate AC in their windings.
• Before the AC leaves the housing it is converted
(rectified) into direct current.
• The rectifier of an alternator is made up of six
silicon diodes.
DC Alternators
• Advantages
• The load current is generated in the stator or
stationary winding and does not have to flow
through brushes.
DC Alternators
• The coils in the stator are connected as three
windings, joined together to form a Y. Three phases
of alternating current are generated.
Voltage Regulator
• Alternator output is controlled (regulated) with a
solid-state voltage regulator.
• Senses the alternator voltage output and controls
the field current to keep this voltage within the
desired range.
• Circuit Breakers are current sensitive devices, not
voltage sensitive, so they provide no protection
against high voltages.
Circuit Control Devices
Circuit Control Devices
• Control Devices
• Switches
– Toggle
– Rocker
– Wafer
– Relay/Solenoids
Relay
Solenoid
Circuit Control Devices
• Protective Devices
• Fuses
• Circuit breakers
– Thermal breakers
– Magnetic breakers
Circuit Control Devices
• Circuit Breakers
• Will automatically open the circuit if the current
becomes excessive.
• May be reset by moving the operating control.
• If a fault such as a short circuit exist the
breaker will trip again, and should be left open.
• Trip-free type.
Circuit Control Devices
• Resistors
• Inserted into circuits to drop voltage by
converting some of the electrical energy into
heat.
• Fixed
• Variable
Circuit Control Devices
• Inductors
• Induced current back flow as the current
induced magnetic field collapses when DC
current is shut off, causing switch contact
arcing.
• Create magnetic fields for relays.
Circuit Control Devices
• Capacitor is a device which will store an electrical
charge (electrons).
•
Quick use: strobe flash
• Can also be used to limit the amount of electrons
flowing in the circuit (an opening switch that is
arcing).
Circuit Control Devices
• Transformer
• Permits voltage of AC current to be increased
or decreased.
• Rectifier
• Converts AC into DC.
• Inverter
• Converts DC into AC.