WorksheetsElectrical Power
Total questions: 76
Worksheet time: 1hrs 17mins
A typical AC power system design
Prevents two sources to the same load at the same time
Encourages two sources to the same load at the same time
Provide 3 phase, 200V at 200Hz
A static inverter uses battery power to make?
AC power
DC power
AC and DC power
Which of these is the correct hierarchy for power distribution?
1. Hot bus 2.Essential bus
3. AC Bus
4. AC Essential bus
5. Non Essential bus
1. Hot bus 2.Essential bus
3. AC Essential Bus
4. AC bus
5. Non Essential bus
1. Essential bus
2. Hotbus
3. AC Bus
4. AC Essential bus
5. Non Essential bus
The aircraft battery is normally directly connected to?
Hot battery bus
DC Essential battery bus
AC Bus
Shed busses or isolation busses are also called?
Non-essential bus
AC bus
Essential DC bus
Under normal operating conditions with both generators on line, the Bus Tie breaker in a parallel DC bus system is?
Closed
Open
Alternating
Under normal operating conditions with both generators on line, the bus tie contactor is what in a Split Bus system?
Open
Closed
Alternating
When does the Bus Tie Contactor in a Split Bus system close?
When only one generator is available
When both generators are available
When neither generators are available
In a Basic Twin Engine AC Bus System, should the AC supply fail, what would be commanded to start and provide emergency AC from the battery?
Static inverter
TRU
Inverter
Tied AC Bus Systems must be synchronised for?
.Equal frequency
.In phase
.Correct Phase rotation
.Equal Output voltage
.Equal frequency
.Out of phase
.Correct Phase rotation
.Inverse Output voltage
.Different frequency
.In phase
.Opposite Phase rotation
.Equal Output voltage
Relays are usually used for?
Low-current switching applications
High current switching applications
Power distribution
The part of the relay attracted by the electromagnet to close the contact points is called?
Armature
Pivot
Spring
What are used to prevent unsynchronised power sources being connected in parallel?
Interlocking circuitry through auxiliary contacts
Interlocking circuitry through essential contacts
Interlocking circuitry through primary contacts
Aircraft, almost without the exception, use a?
Negative ground, single wire earth return system
Positive ground, single wire earth return system
Negative ground, double wire earth return system
Benefit for grounding in a single wire earth system is?
Reduced chance of developing RFI
Less susceptible to arcing
Provides a larger range of voltages
Where does the positive terminal of the battery connect to?
Battery solenoid
Hot bus
Master switch
What is installed across the coil of the solenoid to eliminate spikes when the master switch is opened and the magnetic field from the coil collapses?
Freewheeling diode
Capacitor
Solenoid
What is used to allow the induced EMF to feed back into itself rather than back into the distribution system?
Freewheeling diode
Contactor
Safety relay
Most aircraft isolate the battery if the external DC power is applied to the aircraft. What is the purpose of this?
Stop the build up of hydrogen released from batteries during charging
Protect from overvoltage potentially causing an explosion
So the battery can't supply any extra voltage damaging other systems
Where are the thermistor mounted in a NiCad battery?
Intercell connector link
On the positive lead
On the outer cover
What can be used on a lead acid battery for ventilation?
Sump jar
Oil
Coolant
When installing a battery, always connect the?
Positive lead first
Negative lead first
Positive to the negative terminal
A type of automatic transmission that maintains a constant output rpm with a variable input rpm is called?
Constant speed drive generator
Voltage regulator
DC motor
What should you smear battery lugs with before connection to inhibit corrosion?
Petroleum jelly
Loctite
WD-40
If there is no inbuilt locking device on a battery connector, they should be wired closed with?
26AWG copper wire (Safety wire)
24AWG copper wire (Safety wire)
22AWG copper wire (Safety wire)
The only servicing permitted on lead acid batteries fitted to an airacft is?
Check the electrolyte levels and cleaning the terminals
Check the electrolyte levels
Cleaning the terminals
Lead acid batteries require what to neutralise?
Water and bicarbonate soda
Chromic acid solution
Boric acid solution or vinegar
NiCad batteries spills on aircraft require what to neutralise?
Water and bicarbonate soda
Chromic acid solution
Boric acid solution or vinegar
NiCad battery spills off airacft require what to neutralise?
Water and bicarbonate soda
Chromic acid solution
Boric acid solution or vinegar
The dashpot P provides what in a vibrating type regulator?
Smoother operation by acting as a dampener to prevent hunting
Elimiate sparking
Excess current to build up
Capacitor C across contact B purpose is?
Smoother operation by acting as a dampener to prevent hunting
Eliminate sparking
Over voltage protection
If the solenoid should malfunction or the contacts stick closed, excess current would flow to the field and?
The generator output would increase
The generator output would decrease
The rheostat would fail
L4 is?
Current (series) winding made of a few turns of heavy wire
Voltage (shunt) winding made of many turns of fine wire
Current (series) winding made of a few turns of fine wire
L5 is?
Current (series) winding made of a few turns of heavy wire
Voltage (Shunt) winding made of many turns of fine wire
Voltage (Shunt) winding made of many turns of heavy wire
What is a heavy duty, compound wound generator with differential voltage reverse current cut out relays used to produce current for some large older aircraft?
Carbon pile regulator
Brushless alternator
Voltage regulator
On a carbon pile voltage regulator, what does the leaf spring do in a overvoltage condition?
Releases tension
Builds tension
Adjusts the rheostat
What does the grounded regulator control?
The amount of current in the ground wire to the field winding in the rotor
The amount of current in the battery wire to the field winding in the rotor
The amount of current through the voltage regulator
What does the regulator in a grounded field type voltage regulator control?
The amount of current in the ground wire to the field winding in the rotor
The amount of current in the battery wire to the field winding in the rotor
The amount of current through the voltage regulator
What is the purpose of the surge quench diode?
The diode is reverse bias and will not conduct, protecting T1
The diode is forward bias and will not conduct, protecting T1
The diode is reverse bias and will not conduct, protecting T2
What will happen if the more generator output is required?
The GCU will increase the exciter field current, increasing the exciter armature output and the main field current
The GCU will decrease the exciter field current, decreasing the exciter armature output and the main field current
The GCU will increase the exciter field current, decreasing the exciter armature output and the main field current
A constant speed drive will maintain what frequency?
400 Hz
4800 Hz
1200 Hz
What is used to provide constant speed generator operation in an AC electrical system?
Constant speed drive
Governor drive
Rectifier assembly
What is used for fast line repair of an aircraft that has a defective Integrated Drive Generator?
QAD adapter
Hydraulic release connector
Mechanical slip-nut
A normal operating temperature for oil in an Integrated Generator System is approx?
93 Degrees Celsius
83 Degrees Celcuis
73 Degrees Celsius
After disconnection during flight of a constant speed drive, it can only be reconnected?
On ground
During flight
Anytime
What is a benefit to a Constant Speed Drive generator?
Reduce both weight and size of traditional two unit system
Cannot fail
Can give a variety of frequency outputs
If the adjustment screw is turned clockwise on a Integrated Drive Generator, what will happen?
Increase frequency
Decrease frequency
Change the frequency 3-4 Hz
A 360 degree turn of the adjustment screw on an Integrated Drive Generator will?
Increase the frequency
Decrease the frequency
Change the frequency 3-4Hz
What is a negative to the governor adjustment on a Integrated Drive Generator?
Unstable and erratic frequencies cannot be corrected
Only select frequencies can be corrected
Very short life span
What on a Integrated Drive Generator does not have bypass capabilities and will become blocked causing the IDG to be replaced?
Hydraulic filters
Oil cooler
Charge relief valve
The use of oil cooling in a IDG allows for?
Higher speed rotor
Lower speed rotor
Less friction in the system
What is installed in generator feeder cables to prevent shorting to the airframe?
Differential feeder fault protection
Shielded wiring
Voltage protectors
What is used to convert a portion of DC power to AC power?
Inverter
Converter
Transformer
Which inverter is lighter for the same power rating, but has complications in disturbing multiphase power and in keeping the loads balanced?
Multiphase inverter
Single phase inverter
Static inverter
Which maintenance should not be carried out in the field on an inverter?
Control box on top of the inverter
Complete removal for bench testing
The connector
Which type of inverter has the disadvantages such as lack of frequency control, low surge capability (50% above maximum rating) and lower efficiency (50-80%)?
Rotary inverter
Static inverter
Transformer
What is the major difference between a static inverter and a rotary inverter?
No moving parts in a static inverter
No moving parts in a rotary inverter
There is no differences
What allows the value of AC voltage and current to be changed through the use of mutual inductance?
Transformers
Inverters
Current limiter
Whenever the volts are increased in a transformer, the amperes must?
Decrease by the same ratio
Increase by the same ratio
No change
The conversion of AC to DC is accomplished by a circuit called?
TRU
Transformer
Current limiter
The thermal switch on a TRU system will activate at what temperature to illuminate a warning light?
150-200 degrees C
100-150 degrees C
50-100 degrees C
A star to star transformer's input and output are?
In phase
Out of phase
30 degrees out of phase
A star to delta transformer's input and output are?
In phase
Out of phase
30 degrees out of phase
The parallel rectified outputs of the two secondary windings in a TRU have a DC ripple of?
4800 Hz
1200 Hz
400 Hz
What kind of fuse is commonly found in aircraft power distributions and other high current DC power systems?
Current limiter
Fuse links
Slow blow fuse
A current limiter will take over _______ longer to open than a fast blow fuse?
6 times
3 times
2 times
If a circuit breaker has tripped, what must you do?
Reset it
Isolate the fault and repair it
Replace the circuit breaker
Which circuit breaker will still trip even if trying to reset it?
Trip free
Non trip free
Reverse current
Which circuit breaker can be manually held closed?
Trip free
Non trip free
Reverse current
What is the primary reason why circuit breakers and fuses are so close to the power supply?
Protect the wiring run from short circuits
Protect the component at the end of the wiring
Less RMI from the large variety of voltages and current
What is the secondary feature of placing circuit breakers and fuses so close to the power supply?
Protect the wiring run from short circuits
Protect the component at the end of the wiring
Less RMI from the large variety of voltages and current
What serves the purpose to permit switching of a generator on to the main bus bar and at the same time retain the disconnect function in the event of reverse current in a DC generator system?
Relay
Voltage regulator
Shunt field
Which type of circuit breaker is designed to protect power supply system and associated circuits against currents of a magnitude greater than those at which cut outs normally operate?
Trip free
Non trip free
Reverse current
What is the purpose of the inverse time delay?
Prevent nuisance tripping under transient conditions
Prevent excess current build up through the overvoltage doctor
Act as a relay for the system
Which system is applied to some AC generating systems to provide protection against faults between phases or between one of the phases and ground?
Merz Price Protection
Differential Current Protection
Magnetic Amplifier Overvoltage Protection
The smaller pin on a DC external power receptacle is for?
Interlock sensing and polarity check
Power supply
Ground return
