AF Generators and Alternators
Integrated drive generators employ a type of high output AC generator that utilizes
A brushless system to produce current
Aircraft which operate only AC generators (alternators) as a primary source of electrical power normally provide current suitable for battery charging through the use of
A stepdown transformer band a rectifier
When necessary during operation, CSD disconnect is usually accomplished by
A switch in the cockpit
A CSD unit drives a generator through the use of
A variable hydraulic pump and hydraulic motor
The purpose of a rectifier in an electrical system is to change
Alternating current and direct current
How are generators rated
Amperes at rated voltage
An aircraft electrical circuit control relay is
An electrically operated switch
A battery-generator system provides direct current. On installations requiring alternating current from the battery-generator system, it is necessary to have
An inverter
How is a shunt wound DC generator connected?
Both fields are shunted across the armature
The inductor type inverter output voltage is controlled by the
DC stator field current
What is a method used for restoring generator field residual magnetism
Flash the fields.
What is required when operating two aircraft AC generators in parallel
Frequency and voltage must both be equal.
The voltage in an AC transformer secondary that contains twice as many loops as the primary will be
Greater and the amperage less than in the primary
One advantage of using AC electrical power in aircraft is
Greater ease in stepping the voltage up or down
Which motor would be most likely to have an armature brake?
Landing light retraction motor.
What is the cause of generator brush arcing
Low spring tension.
CSD driven generators are usually cooled by
Oil spray
A CSD unit that is disconnected in flight, due to a malfunction such as overtemperature, may be reconnected
Only on the ground by maintenance personnel
What is the ratio of turns between the primary cool winding and the secondary coul winding of a transformer designed to triple it's input voltage
Primary will have one third as many turns as it's secondary
What is the frequency of an alternator dependent upon
RPM
In an AC circuit with no phase lead or lag, which is true?
Real power equals apparent power.
Certain transport aircraft use AC electrical power for all normal operation and battery furnished DC electrical power for standby emergency use. In aircraft of this type that operate no DC generators, the batteries are kept charged by
Rectifiers which use the aircraft's AC generators as a source of power
If the integrated drive generator (IDG) scavenge oil filter is contaminated with metal, you should
Remove and replace the IDG
The strength of the core of an electromagnet depends upon the material from which it is constructed and which of the following
The number of turns of wire in the coil and the applied voltage
How can it be determined if a transformer winding has some of its turns shorted together
The transformer will get hot in normal operation was
How many cycles of AC voltage are produced in a six pole alternator of the revolving field type for each revolution of the rotor?
Three
Why are the iron cores of most induction coils laminated
To reduce the effects of eddy currents.
What is the maximum amount of time a circuit can be in operation and still be an intermittent duty circuit
Two minutes
How does the magnetic brake used to stop rotation of an electric motor armature operate
a friction brake is applied by a spring and released by a magnet
One purpose of a growler test is to determine the presence of
a shorted armature
During ground operation, aircraft generator cooling is usually accomplished by
an integral fan
If any one generator in a 24-volt dc system shows low voltage, the most likely cause is
an out of adjustment voltage regulator
The major advantages of AC over DC is the fact that it's current and voltage can easily be increased or decreased
by the means of a transformer
The commutator of a generator
changes alternating current produced in the armature into direct current as it is taken from the armature.
The most common method of regulating the voltage output of a compound DC generator is to vary the
current flowing through the shunt field coils
If a generator is equipped with a vibrator-type voltage regulator, the actual time the voltage regulator points remain open
depends on the load carried by the generator
To what depth is a mica insulation between the commutator bars of a DC generator undercut
equal to the width of the mica
The pole pieces or shoes used in a DC generator are a part of the
field assembly
Residual voltage is a result of magnetism in the
field shoes
The starting current of a series wound DC motor is passing through both the field and armature windings produces a
high starting torque
What is the principal advantage it series wound DC motor
high starting torque
When dc generators are operated in parallel to supply power for a single load, their controls include an equalizer circuit to assure that all generators share the load equally. The equalizer circuit operates by
increasing the output of the low generator and decreasing the output of the high generator until they are equal
Which is the most accurate type of frequency measuring instrument
integrated circuit chip having a clock circuit
The method most often used in overcoming the effect of armature reaction is through the use of
interpoles
A series-wound DC electric motor will normally require
more current at low RPM than at high RPM
Some electric motors have two sets of field windings wound in opposite directions so that the
motor can be operated in either direction
The overvoltage control automatically protects the generator system when excessive voltage is present by
opening the shunt field circuit
If the reverse current cutout relay contact points fail to open after the generator output has dropped below battery potential, current will flow through the generator armature
opposite the normal direction and through the shunt field in the normal direction
To test generator or motor armature windings for opens,
place armature in a growler and connect a 110V test light on adjacent segments; light should light.
An armature in a battery charging system is for the purpose of indicating the
rate of current used to change the battery
The poles of a generator are laminated to
reduce eddy current losses
Which of the following is not one of the purposes of interpoles in a generator
reduce field strength
If the positive field lead between a generator and a generator control panel breaks and is shorted while the engine is running, a voltmeter connected to generator output would indicate
residual voltage
A voltage regulator controls generator voltage by changing the
resistance of the generator field circuit
Which type of DC generator is not used as an airplane generator
series wound
When using an ohmmeter to check the continuity of a generator field coil, the coil should
show very low resistance if it is a series field coil
During inspection of an anticollision light installation for condition and proper operation, it should be determined that
the anticollision light can be operated independently of the position lights
In a generator what eliminates any possible sparking to the brush guides caused by the movement of the brushes within the holder
the brush pigtail
In troubleshooting an electrical circuit, if an ohm meter is properly connected across a circuit component and some value of resistance is read,
the component has continuity and is not open
Static inverters are electronic devices that change DC to AC with the
use of an oscillator
A voltage regulator controls generator output by
varying current flow to generator field coil.
The voltage output of an alternator may be regulated by controlling the
voltage output bot the DC exciter
Which of the following are the major parts of a DC motor? 1. armature assembly 2. field assembly 3. brush assembly 4. commutator 5. pole piece 6. rheostat 7. end frame
1, 2, 3, 7
In installations where the ammeter us in the generator or alternator lead, the ammeter can be redlined at what percent of the generator or alternator rating
100%
How can the direction of rotation of a DC electric motor be changed
Reverse the electrical connections to either the field or armature windings.
Where is the generator rating and performance data located
Stamped on the generator data plate