1
Q
What is the purpose of the Aircraft Electrical System?
A
Self contained network of components that generate, utilize, and store electrical energy.
2
Q
What are the three building blocks that make up electrical atoms?
A
- Negative charge is carried by the electrons
- Positive charge is carried by the protons
- Neutrons are neutral
3
Q
When something has an electric charge, what does that mean?
A
Too few or too many electrons
4
Q
How is voltage defined? Units?
A
- Electric potential between two points per unit of charge
- Considered the force that makes electricity move.
- Volts (V)
5
Q
What is current? Units?
A
- Current is created when a conductive path is provided to facilitate movement of electrons in the form of an electrical charge.
- Depends on supply voltage and resistance
- Amps (A)
6
Q
What does Watts mean?
A
- Rate of energy transfer within an electrical system
- Product of V and A
7
Q
What is resistance? What are some factors that affect it?
A
- Measurement of the opposition present to the electrical current flow.
- The lower the resistance the greater the current flow, reducing amount of supply required and size and weight of componentry involved.
- Wire diameter, wire material
8
Q
What materials are good conductors?
A
Metals
9
Q
What materials are bad conductors?
A
Plastic, wood
10
Q
What occurs to the resistance as a conductor heats up? What about when an insulator heats up?
A
- For conductor, resistance increases.
- For insulator, resistance decreases.
11
Q
What is Ohms law? What’s the mathematical equation?
A
- The electrical current in a circuit or conductor will always be proportionate to the voltage across the conductor or circuit and inversely proportional to the total resistance.
- V = IR
12
Q
What is Earth/Ground?
A
- Reference point in an electrical circuit from which voltages are measured
- Used to facilitate protective mechanism should a fault in the system require that power be removed immediately from that circuit.
- This ensures that exposed components never have a dangerous voltage with respect to ground, therefore eliminating the risk of an electrical shock should a “grounded” person touch them.
13
Q
What is a closed circuit?
A
Complete electrical circuit through which current can flow.
14
Q
What is an open circuit?
A
- A state where there is no complete path for current to flow within a circuit.
- Can be by design through components such as switches
15
Q
What is a short circuit?
A
When resistance becomes lower, resulting in an excessive flow of current, excessive heat and failure of components.
16
Q
What is a generator? How does it work?
A
- Device that can generate either AC or DC electricity.
- Through electromagnetic induction, converting mechanical energy into electrical energy.
17
Q
How does electromagnetic induction work?
A
- Moving a magnetic field field in relationship to a conductor.
- Either conductor or magnet can be moving or stationary.
18
Q
What will occur in a generator?
A
A coil of wire is moved through the magnetic field of a powerful electromagnet, producing a large voltage.
19
Q
What is the value of the induced voltage dependent on?
A
- Number of turns in the conductor coil
- Strength of the electromagnet
- Speed of rotation of the conductor or magnet
20
Q
What is alternating current?
A
Electrical current that periodically reverses direction.
21
Q
What does a AC generator consist of?
A
A rectangular coil of wire which can be rotated about an axis.
22
Q
What is required for current to flow ?
A
Generator is electrically connected to an external circuit with an electrical load.
23
Q
What is single and three phase power?
A
- AC generators produce single-phase AC power are less common, as three-phase AC generators are more efficient
- The three-phase supply is able to be used by aircraft equipment designed for single-phase power as well as three-phase power.
- Three phase power has three separate coils of windings 120 degrees apart. Single-phase AC is induced into each coil
24
Q
What is Direct Current (DC)?
A
Unidirectional flow of an electric charge
25
What is the simplest DC generator?
Created by taking the single-loop AC Generator describe previously and replacing the slip rings with two half-cylinders.
26
In a circuit, which way does electricity flow?
Positive to negative
27
What is the point at which current enters an electrical circuit called?
Source or supply
28
What is the point at which current leaves the electrical circuit called?
Return or earth.
29
What are loads in a circuits?
Components in the circuit that required power.
30
What type of applications is AC power used for? What about DC?
- Powering large appliances/loads
| - DC is used for less intense operations such as control circuits and electronics
31
How is resistance determined in a series circuit?
RT = R1 + R2 + R3 ...
32
How is resistance determined in a parallel circuit?
1/RT = 1/R1 + 1/R2 + 1/R3 ...
33
What is insulation?
Material which limits or prohibits current flow
34
What is a resistor?
- Passive electrical component used to induce an electrical resistance.
- Used to regulate current flow, adjust signal levels, divide voltages, and bias current pathways.
35
What is a capacitor?
- Used to store electrical energy within a circuit
| - Eliminate DC but allow AC to pass.
36
What is a transistor?
A semiconductor control device used to amplify or switch electronic signals or electrical power.
37
What is a transformer?
- A device that can be used to change both the voltage and the current of an AC power source (higher or lower).
38
What is a rectifier ?
- A device used to alter current from AC to DC, with the power and voltage levels remaining constant.
39
What is a transformer rectifier units (TRU)?
Performs a combination of transformer and rectifier functions provided above
40
What is an inverter?
Used to alter current from DC to AC.
41
What is a fuse?
Used to facilitate overcurrent protection for an electrical circuit.
42
What is circuit breaker?
- Circuit breaks is an automatically-operate switch design to protect the circuit from damage due to excessive current conditions.
- Designed to be reset by manual or automatic means.
43
What provides electrical power in normal operation of an aircraft?
- Engine-driven generators that provide electrical power
| - Auxiliary power units (APU) or batteries that provide electrical power when the engines are not running.
44
How does a basic electrical system operate?
- Electrical power is supplied by either batteries, APU or onboard power generation to a busbar
- The busbar distributes this electrical power to the reliant systems
- The current then flows through a return wire attached to the aircraft metal structure to complete the circuit
45
What electrical power systems do modern military aircraft use?
- 24V DC (rated at 28V to enable 24V charging of batteries)
| - 115 VAC, 500 Hz, 3-phase generator system
46
Which system do aircraft with low electrical demands usually operate on?
DC-based electrical system
47
Which system do aircraft with high electrical demands usually operate on?
AC-based system.
48
What are some electrical power sources that are commonly used?
- Batteries
- Onboard generators
- Converted electrical power
- Auxiliary electrical power
- Emergency electrical power
49
What is a battery? What are the two types?
- Battery is a device that stores energy in chemical form
| - Two type are: Primary + Secondary
50
What is a primary cell?
Only allow DC power
51
What is a secondary cell?
Allow both charging and discharging of DC power.
52
What is the capacity of a battery?
How much current the battery can provide for a specified time.
53
What is a Transformer Rectifier Unit (TRU) used for?
- A combination of a static transformer, a rectifier and a DC electrical filter.
- Used to convert 115 V AC input to 28 V DC.
54
What are inverters used for? What are the two types?
- Rotary inverter
- Static inverter
- Converts DC into AC
55
Which two systems can provide auxiliary electrical power?
- Ground Power Unit (GPU)
| - Auxiliary Power Unit (APU)
56
What are GPU's used for?
- Aircraft maintenance and servicing.
| - Aircraft systems and engine starting
57
What are Auxiliary Power Units (APU)?
- Capable of providing both electrical and pneumatic power for aircraft starting.
- Provides flexibility for the aircraft to operate in most locations
58
For aircraft with a DC electrical system, what can be used to power vital electrical systems for a short period of time?
Main battery or emergency battery
59
For aircraft with a AC electrical system, what can be used to power vital electrical systems for a short period of time?
- Standby generator driven by:
- Ram air turbine (RAT)
- the APU
- Pneumatic or hydraulic systems
60
What is a ram air turbine?
Turbine that is put into inlet or slipstream to turn a generator to create electricity.
61
What is a busbar?
Main conductor and distribution centre in the electrical system
62
What is the principle of a split busbar?
To divide all electrical services into three categories of importance which allows for manual or automatic isolation of less important systems in the event of an emergency.
63
What are the three categories of importance with regards to electrical services?
1) Vital Services - services required during an emergency
2) Essential services - services that are required to ensure safe flight during in-flight emergencies
3) Non-essential services
- services not essential during flight
64
What is a single channel DC system?
- All essential and non-essential services are fed by a single busbar.
- Streamlined electrics to reduce workload of pilot
65
What is twin channel split busbar DC system?
- Same theoretically as the single channel system but is generally used where there are two generators
- Only different is that non-essential DC services are not powered when only batteries are available for power.
66
What does the voltage regulator do?
Regulates the voltage to ensure it does not get too large/small
67
What provides frequency regulation for AC current?
- Constant Speed Drive Unit (CSDU)
| - Works to regulate the speed of rotation of the generator which determines the frequency of the AC current.
68
What is normally provided as redundancy if the CSDU fails?
Protection Unit
69
What two components are used to control various A/C systems?
1. Switches
| 2 Relays
70
What are electrical switches used for?
To complete or interrupt an electrical circuit
71
What are relays?
Remotely controlled electrical devices used to switch one or more circuits
72
What are some protection devices used?
1. Fuse
2. Circuit breakers
3. Reverse Current Cut-Out (RCCO) sensors
73
In a DC generator, which component ensures the external current in the load only flows one way?
Commutator
74
What is the purpose of a Reverse Current Cut Out (RCCO)?
Disconnect a generator from a busbar if the generator's voltage falls below that of the busbar.
Ground School Systems 2
flashcards
Decks in class (19)
# Cards
-
Flight Control Systems (FCS) Introduction40
-
Hands on Throttle And Stick (HOTAS)14
-
PC-21 Primary Flight Display (PFD)33
-
Primary Flight Display (PFD) Introduction13
-
PC-21 Flight Control Systems (FCS)86
-
Electrical Systems Introduction74
-
PC-21 Electrical System55
-
PC-21 Lighting System42
-
Alerting System Introduction26
-
PC-21 Alerting System66
-
Environmental Control System (ECS) Introduction29
-
PC-21 Environmental Control System (ECS)47
-
Oxygen Systems Introduction36
-
PC-21 Oxygen System39
-
Flight Data Sensors and Miscellaneous Components101
-
PC-21 Flight Data Sensors and Miscellaneous Components54
-
PC-21 Secondary Flight Display11
-
PC-21 Engine Monitoring Display (EMD)14
-
PC-21 Heads Up Display (HUD)45
