AMT 112 Test 2

4 Residual voltage is a result of magnetism in the

field/pole shoes

29 Why are the pole shoes of a generator laminated?

reduce eddy current

78 What is the purpose of the generator control system?

to keep the generator output within limits for all flight variables

19 What is the most basic of the GCU functions?

voltage regulation

31 Two functions of the field frame on DC generators are?

1.) to hold the windings needed to produce a magnetic field 2.) to act as a mechanical support for the other parts of the generator

91 If the frequency strays more than _____% from the value, the electrical systems do not operate correctly.

10%

39 Aircraft AC alternators frequency is approximately _______Hz and the frequency strays more than ______% the electrical systems do not operate correctly.

400Hz, 10%

1 What type of voltage is being produced by the basic generator?

AC

28 The purpose of a rectifier in an electrical system is to change?

AC to DC

86 Why do all AC alternators rotate at a specific RPM

Keep voltage frequency within limits

15 what is the frequency of an alternator dependent upon?

RPM

68 When would it be appropriate to flash a DC generator field?

When performing operational test after inspection

40 AC alternators produce three separate voltages, the sine wave for these voltages are separated by?

120°

24 DC alternator, three phase rectifier assembly is comprised of ____ diodes.

6

41 Light aircraft uses DC power mostly, when only a small amount of AC is required what kind of device is used to provide AC power?

AC inverter

71 How are generators rated?

Amperes at rated voltage

21 the two most common units used to control AC alternators are?

BPCU and GCU

85 Often, aircraft generators have what kind of bearing

Ball bearing

35 How is a shunt wound DC generator connected?

Both fields are shunted across the armature

70 Modern AC alternator is often referred to as

Brushless alternator. 9-42

53 what kind of component is used to change AC to DC in generators

Commutator

87 In a vibrator type regulator, if the contact points remain open the voltage will

Decrease

12 What are the two basic types of generator controls?

Electro mechanical and solid state

51 To what depth is the mica insulation between the commutator bars of a dc generator undercut?

Equal to the width of the mica

25 True or False? DC Alternator brushes carry relatively high current, the brushes of an alternator are typically larger than DC generator brushes.

False

82 __________ are commonly used when only a small amount of AC is required for certain systems. ________ may also be used as a backup AC power source on aircraft that has an AC alternator.

Inverters

46 What is a cause of generator brush arcing?

Low spring tension

81 individual diodes in an alternators rectifier assembly may be tested for opens or shorts by using an

Ohmmeter

36 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

24 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 amount of current (amperes) passing through the coil

61 What is "coming in" speed on generators

The speed at which a generator produces its normal voltage

29 Why are the iron cores of most induction coils laminated?

To reduce the effects of eddy currents

66 In general, DC alternators are lighter and more efficient that DC generator

True

73 The compound DC generators are used where.?

Voltage regulation is of prime importance

80 A small aircraft alternator receives the power during initial operation from?

a battery

32 Find the correct description of the constant speed drive (CSD)

a hydraulic unit similar to an automatic transmission found in a modern automobile. The engine of the automobile can change rpm while the speed of the car remains constant.

18 The output voltage of a shunt generator can be controlled by means of

a rheostat

8 One purpose of a growler test is to determine the presence of

a shorted armature

22 During ground operation, aircraft generator cooling is usually accomplished by

an integral fan

58 DC alternator has two windings. What are they?

armature winding and field winding

10 What are the major parts or assemblies of a DC generator?

armature, field assembly, brush, and end frame

26 What are the two most common types of voltage regulators?

carbon pile regulator and three-unit regulator

56 In a vibrating type voltage regulator, if the system requires more generator output, what is the contact points status?

closed

62 What is a paralleling feature on a generator?

compares the voltages between two or more generators and adjusts the voltage regulation circuit accordingly

27 One unit in the three-unit regulator which contains a relay with a coil wired in series and the unit is sensitive to the current output of the generator. What is this unit?

current limiter

57 Find the three-unit regulator components.

current limiter, reverse current cutout, and a voltage regulator

50 The armature used in DC alternators contains three coils of wire and known as a three phase armature. What is the two common methods used to connect the three phase armature windings?

delta winding and y winding

72 One of the functions of generator control, this is designed to ensure all generator voltage values are within a close tolerance before being connected to the load bus. What is this?

differential voltage

33 In the brushless alternator, the need for brushes is eliminated by what components?

exciter generator, pilot exciter, and main AC alternator. The need for brushes is eliminated by using a combination of these 3 distinct generators.

60 Several alternators are cooled by oil system then how to cool down the oil temperature?

external cooling

54 The pole pieces or shoes used in a DC generator are a part of the

field assembly

74 What is a method used for restoring generator field residual magnetism?

flashing the fields

76 What is any machine that converts mechanical energy into electrical by electromagnetic induction?

generator

35 How is a shunt wound DC generator connected?

in parallel

7 In a series wound DC generator, when the aircraft electrical load is increased, the voltage ___________

increases

5 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

84 When testing alternator diodes with an ohmmeter, an open diode is indicated by a

infinite reading/very high resistance

30 The method most often used to overcome the effect of armature reaction is through the use of

interpoles

67 The effect of armature reaction (the amount that the neutral plane shifts) is proportional to the?

load on the generator

11 Generator rating and performance data are located?

on the generator plate

83 You are testing an alternator rotor with an ohmmeter. When the probes of the ohmmeter are placed on the slip rings of the rotor the ohmmeter reads infinity ohms, it is an indication of a/an

open

75 The overvoltage control automatically protects the generator system when excessive voltage is present by

opening the shunt field circuit

9 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.

17 On multiengine aircraft, a ____________ feature must be employed to ensure all generators operate within limits

paralleling

2 What is the component to connect each brush to the external circuit on a generator?

pig tail

47 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.

44 An ammeter in a battery charging system is for the purpose of indicating the

rate of current used to charge the battery

49 Some components on the alternator replace the commutator and brushes found on DC generators. What is this?

rectifier assembly

38 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

37 A voltage regulator controls generator voltage by changing the

resistance of the generator field circuit

63 What is the component name which opens the generator relay and disconnects the generator from the bus is current is flowing to the generator, not from the generator?

reverse current

65 In a starter-generator, during the start function, which field GCU must energize?

series field

16 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

77 What type of generator is being described from the following sentences? "The field winding is connected in parallel to the load and the armature, and all the current flowing in the external circuit passes only through the armature winding."

shunt-wound

43 One regulator type has no moving parts and is generally considered to be more reliable and provide better regulation than vibrating-type regulator. What is this?

solid state regulator

55 The only practical method of maintaining a constant voltage output from an aircraft generator under varying conditions of speed and load is to vary the

strength of a magnetic field

14 what does directly effect on the generator output?

strength of the magnetic field

34 To control AC alternators, the two most common units used are?

the bus power control unit (BPCU) and the GCU

3 Find the correct description regarding the external circuit on DC generators.

the external circuit is the electrical load powered by the generator

89 Which one describes about solid state regulators on DC alternator?

they rely on transistor circuitry to control alternator field current and alternator output

13 What is the purpose of the pigtail on a generator?

to conduct the current from the armature through the brushes, to the external circuit of the generator

59 What category aircraft employs AC alternators?

transport

52 A voltage regulator controls generator output voltage by

varying current flow to generator field coil

45 The voltage output of an alternator may be regulated by controlling the

voltage output of the dc exciter

79 What is the component to prevent too high voltage on a DC generator three unit regulator?

voltage regulator

20 The unit/component found in almost all voltage regulation is?

zener diode

42 What is the key component of any solid-state regulator?

zener diode

64 In a carbon pile, describe the symptoms if the resistance of the disks decreases

(1) The field current increases (2) Generator output increases

48 What are two types of regulators are used on most DC alternators?

(1) Vibrator type (2) Solid state type

90 Commutators and/or slip rings may be polished with

000 sandpaper or crocus cloth