AS356 Basics of Electricity, Oxygen and Pressurization
What current is generated in the Armature
AC
Temperature control
Air from a pressure source is mixed with cool air by a thermostatically controlled bypass valve
What factors will determine EPT
Altitude Rate of ascent Physical Activity Day-to-Day factors
Series Circuit
Amount of current is the same through any component in the circuit because there is only one path.
OBOGS
An absorbent is used to remove nitrogen from the air, which in turn enriches the oxygen concentration. Uses Zeolite
Commutator
An attachment connected to the armature of a motor or generator where the electrical connection is made which ensures the current is direct current
Differential control
Automatically limits cabin pressure to maximum allowable differential pressure
Benefits of an alternator over a generator
Charge a battery at idle Support higher amps More reliable Fewer hard to diagnose problems
What is DC used for
Charging Batteries Control higher voltage AC power
What changes a current from AC to DC in a generator
Commutator
Alternator
Converts mechanical energy to electrical energy in the form of an alternating current
Current
Current is charged particles which flow from the voltage source through conductive material to a ground. Measured in amps.
Alternating Current
Direction reverses cyclically cycle per seconds = hertz
Transformer
Due to an effect of electromagnetism you can decrease or increase AC voltage by placing different length winding coils next to each other
Voltage
Electrical potential difference between two points on a conducting wire. Measured in volts.
Inverter
Electromechanical device that converts DC to AC.
What is flux?
Flux is the presence of a force field in a specified physical medium, of the flow of energy through a surface.
Watt
Measure of energy rate conversion
Ammeter
Measures current flow
Loadmeter
Measures the load in an alternator, generator, busbar
Temporary Magnet
Needs the presence of a magnet field to act like a magnet
Conventional Flow Notation
Negative to Positive
Electron Flow Notation
Negative to Positve
What 3 things does DC voltage depend on
Number of lines of Magnetic flux Number of conductors cutting the flux Speed at which conductors move through flux
Two ways to produce the magnetic field in an alternator
Permanent magnets which create their own persistent magnetic field or by using field coils.
What is Ohm's law
Physical Relationship of voltage, current, and resistance.
Pressure demand System
Provides oxygen under positive pressure
Isobaric control
Regulator maintains cabin pressure and rate of change of cabin pressure selected by the pilot
Continuous flow system
Regulator provides flow of oxygen with no user demand
Permanent Magnet
Retain magnetism once magnetized
What causes a generator to produce DC current
Split-ring commutator
Cabin Pressurization System Requirements
Suitable cabin structure Source of compressed air Temperature regulation Regulation of pressure and rate of pressure change Control outflow of air from cabin
Benefits of AC generators
Tend to be simpler and therefore have greater reliability and lower cost
What effect does the speed of the armature have on a generator
The current and voltage is directly proportional to the speed the armature spins and to the strength of the magnetic feild
Resistance
The opposition that a material body offers to the passage of an electric current. Measured in ohms.
Armature
The part of an electric motor or generator that produces an electrical current when it turns in a magnetic field.
Electromotive force
The resistive force that wants to move from a lower to a higher potential.
Parallel Circuit
There are many paths for electrons to flow, but only one voltage across all components
Direct Current
Unidirectional Flows in a constant direction, current does not alternate. One polarity of voltage or current
Bonding Strap
Used to create an electrical path for electrons to pass from item to item
Diluter Demand System
User must inhale to get 02
Demand System
User must inhale to place a demand on the 02 system
Solenoid
Uses magnetism to open and close an electrical circuit. Has a mechanical movable core.
Relay
Uses magnetism to open and close an electrical circuit. No movable core.
Wires inside or outside on a generator?
Wire coil on the inside, magnet on the outside
Electromagnet
Wound coils of wire that function as magnets when an electrical current is passed through. Stronger the electromagnet the stronger the magnetic feild
What is generator magnetic field controlled by?
electro-magnet
Alternator set up
magnetic field spins inside winding wires
Oxygen regulaton
no person may operate an aircraft above 1200-14000 unless flight crew uses oxygen. Above 14000 the entire flight. Above 15000 each occupant is provided with oxygen
Rectification and Recifier
the conversion of alternating current to direct current. AC to DC.
