2A672 Volume 1 Quiz

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Quizzes Created: 4 | Total Attempts: 900

Questions: 60 | Attempts: 397 | Updated: Mar 20, 2023

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Unit Review Questions from CDC 2A672 Volume 1

Questions and Answers

1.

What is the simplest form of matter?
- A.
  
  Element
- B.
  
  Mixture
- C.
  
  Electrons
- D.
  
  Compound
Correct Answer
A. Element

Explanation
An element is the simplest form of matter because it consists of only one type of atom. It cannot be broken down into simpler substances by chemical means. In contrast, a mixture is a combination of two or more substances, and a compound is a substance made up of two or more different elements chemically combined. Electrons, on the other hand, are subatomic particles and not a form of matter on their own.

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2.

In an atom, what electrons contain the most energy?
- A.
  
  The energy is shared equally by all electrons
- B.
  
  Orbiting electrons
- C.
  
  Valence electrons
- D.
  
  K shell electrons
Correct Answer
C. Valence electrons

Explanation
Valence electrons are the electrons in the outermost shell of an atom. These electrons are involved in chemical reactions and are responsible for the atom's ability to form bonds with other atoms. Since valence electrons are farther from the nucleus compared to other electrons, they experience less attraction from the positive charge of the nucleus. This results in valence electrons having higher energy levels compared to electrons in inner shells. Therefore, valence electrons contain the most energy in an atom.

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3.

Atoms having more than four electrons, but less than eight are known as
- A.
  
  Insulators
- B.
  
  Conductors
- C.
  
  Stable atoms
- D.
  
  Semiconductors
Correct Answer
A. Insulators

Explanation
Atoms having more than four electrons, but less than eight are known as insulators. Insulators are materials that do not conduct electricity easily because their outermost electron shells are fully occupied or nearly fully occupied. This means that they have a stable electron configuration and do not readily gain or lose electrons to become charged ions. As a result, insulators have high resistivity and do not allow the flow of electric current easily.

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4.

The electrostatic fields around a positive ion move
- A.
  
  Inward
- B.
  
  Outward
- C.
  
  Inward, then outward
- D.
  
  Outward, then inward
Correct Answer
B. Outward

Explanation
The electrostatic fields around a positive ion move outward. This is because positive ions have a deficiency of electrons, resulting in an excess of positive charge. As a result, the positive charge is repelled and moves away from the ion, creating an outward flow of the electrostatic fields.

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5.

What are factors that affect the resistance of a material?
- A.
  
  Area, weight, and state of material
- B.
  
  Area, temperature, and type of material
- C.
  
  Temperature, weight, and state of material
- D.
  
  Temperature, type of material, and state of material
Correct Answer
B. Area, temperature, and type of material

Explanation
The factors that affect the resistance of a material are the area, temperature, and type of material. The area of the material affects resistance because a larger area allows for more current to flow, resulting in lower resistance. The temperature of the material affects resistance because as the temperature increases, the resistance also increases. The type of material affects resistance because different materials have different resistivities, which determine how easily they allow current to flow.

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6.

What is the resistance in a circuit if the power rating is 40 watts and total current is 2 amps?
- A.
  
  40 ohms
- B.
  
  20 ohms
- C.
  
  10 ohms
- D.
  
  0.5 ohms
Correct Answer
C. 10 ohms

Explanation
40/2^2 = 40/4 = 10 ohms

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7.

Convert 500 milliamps to standard amperage.
- A.
  
  .005 amps
- B.
  
  .05 amps
- C.
  
  .5 amps
- D.
  
  50 amps
Correct Answer
C. .5 amps

Explanation
To convert milliamps to standard amperage, you divide the value by 1000. In this case, 500 milliamps divided by 1000 equals 0.5 amps.

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8.

In a series-parallel circuit, find RT if series resistor R1 = 7 ohms, and parallel resistors R2 and R3 = 8 ohms.
- A.
  
  23 ohms
- B.
  
  15 ohms
- C.
  
  11 ohms
- D.
  
  8 ohms
Correct Answer
C. 11 ohms

Explanation
Find RT of parallel resistors: RT = 8x8/8+8 = 64/16 = 4
New R2 is RT of parallel resistors. Now use RT = R1 (7) + R2 (4) = 11 ohms

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9.

In a series-parallel circuit, the series current at I1 = 9 amps; in the two parallel branches, I2 = 5 amps; and the value of I3 is not listed. Use Ohms's law to find the value of I3 and IT.
- A.
  
  I3 = 5 amps and IT = 14 amps
- B.
  
  I3 = 4 amps and IT = 9 amps
- C.
  
  I3 = 4 amps and IT =18 amps
- D.
  
  Not enough information to solve
Correct Answer
B. I3 = 4 amps and IT = 9 amps

Explanation
Total current is equal throughout series part of circuit. So since I1 (in series part) = 9 amps, IT = 9 amps. Parallel branches always add up to equal current flow in series part. So, I2 (5 amps) + I3 (?) = 9 amps. I3 has to equal 4 amps.

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10.

What is the difference between and open and a short?
- A.
  
  An open causes resistance to decrease; a short causes resistance to increase
- B.
  
  Excessive current flow in an open circuit; no current flow in a shorted component
- C.
  
  No current flow in an open circuit; excessive current flow in a shorted component
- D.
  
  Minimum voltage development across the open component; maximum voltage development across the shorted component
Correct Answer
C. No current flow in an open circuit; excessive current flow in a shorted component

Explanation
In an open circuit, there is no complete path for the current to flow, resulting in no current flow. On the other hand, in a short circuit, there is a direct connection between two points with very low resistance, causing excessive current flow. Therefore, the correct answer is "No current flow in an open circuit; excessive current flow in a shorted component."

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11.

Voltage induced into a conductor by the expanding and collapsing of a magnetic field is
- A.
  
  Magnetism
- B.
  
  Reluctance
- C.
  
  Direct current
- D.
  
  Electromagnetic induction
Correct Answer
D. Electromagnetic induction

Explanation
Electromagnetic induction is the correct answer because when a magnetic field expands or collapses, it creates a change in magnetic flux through a conductor. This change in magnetic flux induces a voltage in the conductor according to Faraday's law of electromagnetic induction. This phenomenon is the basis for the generation of electric power in generators and is a fundamental principle in electromagnetism.

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12.

In an inductor, what happens to the magnetic lines of force if the diameter of the core is increased in size?
- A.
  
  Permeability increases
- B.
  
  Magnetic field decreases
- C.
  
  Induction of the coil increases
- D.
  
  Induction of the coil decreases
Correct Answer
C. Induction of the coil increases

Explanation
When the diameter of the core in an inductor is increased in size, it allows for more magnetic lines of force to pass through the coil. This increase in magnetic lines of force leads to a higher level of induction of the coil.

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13.

What is the basic principle of operation for transformers?
- A.
  
  Mutual induction
- B.
  
  Magnetic induction
- C.
  
  Counterelectromotive force
- D.
  
  Primary and secondary induction
Correct Answer
A. Mutual induction

Explanation
Mutual induction is the basic principle of operation for transformers. This principle states that when the current in the primary coil of a transformer changes, it creates a changing magnetic field. This changing magnetic field induces a voltage in the secondary coil, which can then be used to transfer electrical energy from one circuit to another. Mutual induction allows transformers to efficiently increase or decrease the voltage of an alternating current while maintaining power conservation.

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14.

What type of transformer contains more turns in the primary winding than in the secondary winding?
- A.
  
  Current
- B.
  
  Step up
- C.
  
  Rectifier
- D.
  
  Step down
Correct Answer
D. Step down

Explanation
A step-down transformer contains more turns in the primary winding than in the secondary winding. This type of transformer is designed to reduce the voltage level from the primary side to the secondary side. By having more turns in the primary winding, the transformer increases the voltage on the primary side and decreases it on the secondary side, resulting in a step-down effect. This is commonly used in power distribution systems to lower the high voltage from power plants to a safer and more usable level for homes and businesses.

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15.

If the size of the plates of a capacitor is increased, how is capacitance affected?
- A.
  
  Capacitance increases
- B.
  
  Capacitance decreases
- C.
  
  Electrons are distorted and scattered
- D.
  
  Electrostatic force between the plates decreases
Correct Answer
A. Capacitance increases

Explanation
When the size of the plates of a capacitor is increased, the capacitance increases. This is because capacitance is directly proportional to the area of the plates. As the size of the plates increases, there is more surface area available for the electric field to store charge, resulting in an increase in capacitance.

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16.

What statement best describes a capacitive circuit?
- A.
  
  Current leads applied voltage by 90 degrees
- B.
  
  Applied voltage leads current by 90 degrees
- C.
  
  Has the ability to conduct in one direction and not in the other
- D.
  
  Has the ability to conduct in all directions when gated or discharged
Correct Answer
A. Current leads applied voltage by 90 degrees

Explanation
A capacitive circuit is characterized by the fact that the current leads the applied voltage by 90 degrees. This means that the current reaches its maximum value before the voltage does, and the phase angle between the current and voltage is 90 degrees. This behavior is typical of capacitors, which store and release energy in response to changes in voltage.

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17.

How many electrons does the valance band of an intrinsic semiconductor have?
- A.
  
  3
- B.
  
  4
- C.
  
  5
- D.
  
  6
Correct Answer
B. 4

Explanation
The valence band of an intrinsic semiconductor has 4 electrons. In an intrinsic semiconductor, the valence band is completely filled with electrons at absolute zero temperature. Each electron in the valence band is bonded to its respective atom's nucleus, creating a stable lattice structure. These valence electrons are responsible for the semiconductor's electrical conductivity.

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1
0
18.

What are the minority carriers in P-type material?
- A.
  
  Holes
- B.
  
  Protons
- C.
  
  Neutrons
- D.
  
  Electrons
Correct Answer
D. Electrons

Explanation
In P-type material, the majority carriers are holes, which are positively charged. Minority carriers, on the other hand, are the minority of charge carriers in the material. In P-type material, the minority carriers are electrons, which are negatively charged. These electrons are present due to the doping of the material with impurities, which introduces extra electrons into the crystal lattice.

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19.

The area of a semiconductor where P-type material is joined to N-type material is known as
- A.
  
  Dielectric region
- B.
  
  Depletion region
- C.
  
  Depletion field
- D.
  
  PN region
Correct Answer
B. Depletion region

Explanation
The area where P-type material is joined to N-type material in a semiconductor is known as the depletion region. This region is depleted of majority carriers due to the diffusion of minority carriers from both sides, creating a region with no free charge carriers. The depletion region acts as a barrier to the flow of current and plays a crucial role in the operation of semiconductor devices such as diodes and transistors.

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20.

A junction diode has how many PN junction(s)?
- A.
  
  1
- B.
  
  2
- C.
  
  3
- D.
  
  4
Correct Answer
A. 1

Explanation
A junction diode has only one PN junction. A PN junction is formed by the combination of a P-type semiconductor and an N-type semiconductor, creating a boundary between the two regions. This junction is responsible for the diode's characteristic behavior, allowing current to flow in one direction while blocking it in the opposite direction. Therefore, a junction diode has one PN junction.

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21.

In a circuit using a bridge rectifier, how many diodes are forward biased during the first cycle of alternating current (AC)?
- A.
  
  4
- B.
  
  3
- C.
  
  2
- D.
  
  1
Correct Answer
C. 2

Explanation
During the first cycle of alternating current (AC) in a circuit using a bridge rectifier, two diodes are forward biased. A bridge rectifier consists of four diodes arranged in a bridge configuration. During the positive half cycle of the AC input, two diodes (D1 and D2) become forward biased and conduct current, while the other two diodes (D3 and D4) are reverse biased and do not conduct. This allows the positive half cycle of the AC input to pass through the circuit. Therefore, the correct answer is 2.

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22.

If a zener diode is installed in the forward bias mode in a circuit, it acts as a
- A.
  
  Regular diode
- B.
  
  Spike protector
- C.
  
  Voltage reference
- D.
  
  Voltage regulator
Correct Answer
A. Regular diode

Explanation
When a zener diode is installed in the forward bias mode, it behaves like a regular diode. In this mode, the diode allows current to flow in the forward direction, just like a normal diode. The zener diode will not exhibit its characteristic zener breakdown voltage behavior in forward bias mode. Therefore, it will not act as a spike protector, voltage reference, or voltage regulator. Instead, it will function as a regular diode, allowing current to flow in the forward direction and blocking it in the reverse direction.

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23.

How is a zener diode connected in a circuit to regulate voltage?
- A.
  
  In parallel to the load
- B.
  
  In series with the load
- C.
  
  In parallel to the resistor
- D.
  
  In series with the resistor
Correct Answer
A. In parallel to the load

Explanation
A zener diode is connected in parallel to the load in order to regulate voltage. When connected in this manner, the zener diode acts as a voltage regulator by maintaining a constant voltage across the load, regardless of variations in the input voltage. This is achieved by allowing current to flow through the zener diode in the reverse direction when the voltage exceeds the zener breakdown voltage. This ensures that the voltage across the load remains constant, providing a stable power supply for the circuit.

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24.

If a schematic diagram doesn't list a reference for the zener diode, the diode is probably being used as a
- A.
  
  Reference
- B.
  
  Normal diode
- C.
  
  Spike protector
- D.
  
  Voltage regulator
Correct Answer
C. Spike protector

Explanation
If a schematic diagram doesn't list a reference for the zener diode, it is likely being used as a spike protector. A spike protector is a device that protects electronic circuits from voltage spikes or surges. Zener diodes are commonly used in spike protection circuits because they have a breakdown voltage that allows them to conduct when the voltage exceeds a certain threshold. By diverting excessive voltage away from the circuit, the zener diode helps to protect the components from damage. Therefore, if a schematic diagram doesn't specify the purpose of the zener diode, it is reasonable to assume that it is being used as a spike protector.

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25.

How is the zener diode connected in a circuit to protect the load?
- A.
  
  In parallel to the resistor
- B.
  
  In series with the load
- C.
  
  In parallel to the load
- D.
  
  Forward biased
Correct Answer
C. In parallel to the load

Explanation
The zener diode is connected in parallel to the load in order to protect it. When the voltage across the load exceeds the breakdown voltage of the zener diode, it starts conducting in reverse bias and limits the voltage across the load. This prevents the load from being damaged by excessive voltage.

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26.

What is the primary use of a silicon-controlled rectifier (SCR)?
- A.
  
  Electronic switch
- B.
  
  Voltage regulator
- C.
  
  Circuit amplifier
- D.
  
  Spike protector
Correct Answer
A. Electronic switch

Explanation
A silicon-controlled rectifier (SCR) is primarily used as an electronic switch. It is a semiconductor device that can control the flow of electric current. When a small control current is applied to the gate terminal, the SCR allows a larger current to flow from the anode to the cathode. This makes it useful for applications where precise control of high-power AC or DC currents is required, such as in motor control, power supplies, and lighting systems. The SCR can turn on and off rapidly, making it an efficient and reliable electronic switch.

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27.

The silicon-controlled rectifier (SCR) has how many layers?
- A.
  
  1
- B.
  
  2
- C.
  
  3
- D.
  
  4
Correct Answer
D. 4

Explanation
The silicon-controlled rectifier (SCR) is a four-layer semiconductor device that acts as a switch for high-power electrical circuits. It consists of three P-N junctions and four layers of alternating P-type and N-type materials. The four layers allow the SCR to control the flow of current in a circuit by using a small triggering current to turn on a larger current.

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28.

If a small potential is applied to the gate of a silicon-controlled rectifier (SCR), the
- A.
  
  Middle junction of the SCR is reversed biased and the SCR turns off
- B.
  
  Middle junction of the SCR is forward biased and the SCR turns on
- C.
  
  Depletion region increases in size and blocks current flow
- D.
  
  Depletion region decreases in size and stops current flow
Correct Answer
B. Middle junction of the SCR is forward biased and the SCR turns on

Explanation
When a small potential is applied to the gate of an SCR, it causes the middle junction of the SCR to become forward biased. This means that the voltage at the gate is higher than the voltage at the cathode, allowing current to flow through the SCR and turning it on.

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29.

What is the major difference between an NPN transistor and a PNP transistor?
- A.
  
  A PNP transistor can only be used as a regulator
- B.
  
  An NPN transistor can only be used as a switch
- C.
  
  Direction of current flow
- D.
  
  Number of junctions
Correct Answer
C. Direction of current flow

Explanation
The major difference between an NPN transistor and a PNP transistor is the direction of current flow. In an NPN transistor, the current flows from the collector to the emitter, while in a PNP transistor, the current flows from the emitter to the collector. This difference in current flow direction is due to the arrangement and doping of the semiconductor materials within the transistor.

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30.

If the arrow in a bipolar transistor is pointing away from the base, what type of transister is it?
- A.
  
  N-type
- B.
  
  P-type
- C.
  
  NPN
- D.
  
  PNP
Correct Answer
C. NPN

Explanation
If the arrow in a bipolar transistor is pointing away from the base, it indicates that the transistor is an NPN type. In an NPN transistor, the majority charge carriers are negative electrons, hence the arrow pointing away from the base represents the flow of electrons from the emitter to the base and then to the collector.

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31.

The circuit in the bipolar transistor that carries 5 percent of the current flow is the
- A.
  
  Basecircuit circuit
- B.
  
  Load circuit
- C.
  
  Control circuit
- D.
  
  Emmiter-collector
Correct Answer
C. Control circuit

Explanation
The control circuit in a bipolar transistor is responsible for regulating the flow of current. It determines the amount of current that flows through the transistor by controlling the base current. In this case, since the control circuit carries only 5 percent of the total current flow, it indicates that it has a smaller role in controlling the overall current flow compared to the other circuits.

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32.

What happens if the emitter-base (E-B) current is increased in a transistor amplifier?
- A.
  
  Resitance decreases and current through the load circuit decreases
- B.
  
  Current decreases through the emitter-collector (E-C) circuit
- C.
  
  Resistance increases and current flow decreases
- D.
  
  Current increases through the E-C circuit
Correct Answer
D. Current increases through the E-C circuit

Explanation
If the emitter-base current is increased in a transistor amplifier, it will cause the current to increase through the emitter-collector (E-C) circuit. This is because the emitter-base junction acts as a current amplifier, and an increase in the input current will result in a proportional increase in the output current through the E-C circuit.

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33.

How many junctions are in a unijunction transister (UJT)?
- A.
  
  1
- B.
  
  2
- C.
  
  3
- D.
  
  4
Correct Answer
A. 1

Explanation
A unijunction transistor (UJT) typically has only one junction. This junction is formed between the emitter and the base regions of the transistor. The UJT operates by controlling the current flow between the emitter and the base junction, which in turn controls the current flow between the emitter and the collector terminals. Therefore, the correct answer is 1, as there is only one junction in a UJT.

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34.

What are the three leads in a unijunction transistor (UJT) called?
- A.
  
  Anode, cathose, and gate
- B.
  
  Emitter, base 1, and base 2
- C.
  
  Emitter, collector, and base
- D.
  
  Common emitter, common collector, and common base
Correct Answer
B. Emitter, base 1, and base 2

Explanation
The three leads in a unijunction transistor (UJT) are called emitter, base 1, and base 2.

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35.

The emitter in a unijunction transister always points toward the
- A.
  
  Base 1 lead
- B.
  
  Collector
- C.
  
  Emitter
- D.
  
  Gate
Correct Answer
A. Base 1 lead

Explanation
The emitter in a unijunction transistor always points toward the base 1 lead. This is because the base 1 lead is the terminal that controls the current flow through the transistor. By pointing the emitter towards the base 1 lead, the transistor is able to regulate the current effectively. The emitter is responsible for emitting the majority charge carriers, and by aligning it with the base 1 lead, the transistor can function properly and perform its intended tasks.

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36.

The amount of voltage it takes for a unijunction transistor (UJT) to fire is determined by the position
- A.
  
  The emitter is placed on the N-type material
- B.
  
  The emitter is placed on the P-type material
- C.
  
  Of B1 and B2 on the P-type material
- D.
  
  Of the UJT in the circuit
Correct Answer
A. The emitter is placed on the N-type material

Explanation
The correct answer is that the amount of voltage it takes for a unijunction transistor (UJT) to fire is determined by the position of the emitter on the N-type material. This is because the UJT is a three-layer, two-junction semiconductor device, with one of the junctions being the emitter-base junction. The position of the emitter on the N-type material affects the characteristics of this junction and determines the firing voltage of the UJT. Placing the emitter on the N-type material allows for the desired voltage threshold to be achieved for the UJT to fire.

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37.

What controls the firing time of the unijunction transistor (UJT)?
- A.
  
  Intrinsic standoff ratio
- B.
  
  Resistance in the circuit
- C.
  
  Capacitance in the circuit
- D.
  
  Resistance and capacitance in the circuit
Correct Answer
D. Resistance and capacitance in the circuit

Explanation
The firing time of the unijunction transistor (UJT) is controlled by the resistance and capacitance in the circuit. These two components determine the charging and discharging times of the UJT, which in turn affect the firing time. The resistance determines the rate at which the capacitor charges, while the capacitance determines the amount of charge that can be stored. By adjusting these values, the firing time of the UJT can be controlled.

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38.

In what position must the line drop switch be placed when adjustments are made to a voltage regulator?
- A.
  
  ON
- B.
  
  OFF
- C.
  
  Adjust
- D.
  
  Regulator
Correct Answer
A. ON

Explanation
The line drop switch must be placed in the ON position when adjustments are made to a voltage regulator. This is because the ON position allows the flow of electricity through the regulator, enabling adjustments to be made to the voltage output. Placing the switch in the OFF position would interrupt the flow of electricity and prevent any adjustments from being made. The Adjust and Regulator options are not relevant to the position of the line drop switch.

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39.

What component of the voltage regulator compensates for losses in the power cable by sensing changes in current flow?
- A.
  
  Load rheostat
- B.
  
  No load rheostat
- C.
  
  Line drop switch
- D.
  
  Voltage adjustment rheostat
Correct Answer
A. Load rheostat

Explanation
The load rheostat is the component of the voltage regulator that compensates for losses in the power cable by sensing changes in current flow. It adjusts the resistance in the circuit to regulate the voltage output and ensure that it remains constant, compensating for any losses in the power cable. The load rheostat helps to maintain a stable and reliable power supply by adjusting the current flow as needed.

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40.

The portion of the voltage regulator that supplies exciter field voltage is transformer
- A.
  
  (T1) and rectifier (B3)
- B.
  
  (T3) and rectifier (B2)
- C.
  
  (T2) and rectifier (B1)
- D.
  
  (T1) and rectifier (CR26)
Correct Answer
D. (T1) and rectifier (CR26)

Explanation
The correct answer is (T1) and rectifier (CR26). In a voltage regulator, the exciter field voltage is supplied by a transformer (T1) and a rectifier (CR26). The transformer steps down the voltage from the main generator and the rectifier converts the AC voltage into DC voltage. This combination of T1 and CR26 ensures that the exciter field receives the appropriate voltage to regulate the output voltage of the generator.

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41.

What component controls the strength of the -86D exciter field L2?
- A.
  
  Excitation relay K16
- B.
  
  Time delay relay K14
- C.
  
  Voltage regulator VR1
- D.
  
  Automatic manual switch S1
Correct Answer
C. Voltage regulator VR1

Explanation
The voltage regulator VR1 controls the strength of the -86D exciter field L2. This means that it regulates the voltage supplied to the exciter field, which in turn determines the strength of the field. By adjusting the voltage, the voltage regulator can control the output of the exciter field and ensure that it is at the desired level.

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42.

A -86D is operating and the alternating current (AC) voltmeter is reading 200 volts alternating current (VAC) on all three phases. What do you do?
- A.
  
  Adjust VR1
- B.
  
  Adjust R61
- C.
  
  Adjust VR1 or R61
- D.
  
  Switch S15 to the L-N position
Correct Answer
D. Switch S15 to the L-N position
43.

While operating a -86D at governed speed, you place S13 in the build up position and the undervoltage light comes on. What is the probable cause of this trouble?
- A.
  
  Voltage regulator
- B.
  
  Plug interlock relay
- C.
  
  Memory time delay relay
- D.
  
  Overvoltage/undervoltage relay
Correct Answer
C. Memory time delay relay

Explanation
The probable cause of the undervoltage light coming on when placing S13 in the build up position while operating a -86D at governed speed is the memory time delay relay.

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44.

The -86D is applying 115 VAC to the aircraft and all of a sudden the AC contactor opens and there is no voltage indication on M2. What is the probable cause of this trouble?
- A.
  
  Load contactor
- B.
  
  CR 17 forward biased
- C.
  
  Overvoltage/undervoltage relay
- D.
  
  Memory time-delay relay energized
Correct Answer
D. Memory time-delay relay energized

Explanation
The probable cause of the trouble is that the memory time-delay relay is energized. This relay is designed to introduce a time delay before allowing power to be applied or removed from a circuit. In this case, it is likely that the memory time-delay relay has been activated, causing a delay in supplying voltage to M2. This could be due to a malfunction or a preset time delay that has been triggered.

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45.

You are driving on the flight line and notice a -86D power unit with all the fault lights on. You try to reset S23, but the lights stay on. What is a probable cause of this trouble?
- A.
  
  S30 is shorted
- B.
  
  S23 is stuck open
- C.
  
  K17 contacts are closed
- D.
  
  K23 contacts are open
Correct Answer
A. S30 is shorted

Explanation
If the -86D power unit has all the fault lights on and resetting S23 does not fix the issue, a probable cause of this trouble could be that S30 is shorted. A shorted S30 would prevent the fault lights from turning off even after attempting to reset S23.

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46.

What component on the B809A generator set fuel system distributes and delivers an accurate amount of fuel to the engine cylinders?
- A.
  
  Injector pump
- B.
  
  Transfer pump
- C.
  
  Injector nozzles
- D.
  
  Throttle actuator
Correct Answer
A. Injector pump

Explanation
The injector pump is the component on the B809A generator set fuel system that distributes and delivers an accurate amount of fuel to the engine cylinders. It is responsible for pressurizing the fuel and injecting it into the cylinders at the correct time and in the correct quantity to ensure efficient combustion. The injector pump plays a crucial role in maintaining the engine's performance and fuel efficiency.

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47.

What contacts on the annunciator card of the B809A generator set control the alternating current (AC) power input to the voltage regulator?
- A.
  
  Engine fault
- B.
  
  Regulator fault
- C.
  
  Generator fault
- D.
  
  Contactor fault
Correct Answer
C. Generator fault

Explanation
The contacts on the annunciator card of the B809A generator set that control the AC power input to the voltage regulator are referred to as "generator fault." These contacts are responsible for monitoring and detecting any faults or issues related to the generator. When a fault is detected, these contacts will send a signal to the voltage regulator, indicating that there is a problem with the generator's AC power input.

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48.

What signal powers the regulator card output pulse sent to the exciter field of the B809A generator?
- A.
  
  28.5 volts direct current (VDC)
- B.
  
  110 VDC
- C.
  
  115 volts alternating current (VAC)
- D.
  
  200 VAC
Correct Answer
B. 110 VDC

Explanation
The regulator card output pulse sent to the exciter field of the B809A generator is powered by 110 VDC. This means that the pulse is generated using a direct current with a voltage of 110 volts.

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49.

What B809A generator set engine safety circuit incorporates a seven-second time delay before activation?
- A.
  
  Low fuel fault
- B.
  
  Overspeed fault
- C.
  
  Low lube pressure
- D.
  
  Coolant temperature
Correct Answer
C. Low lube pressure

Explanation
The correct answer is low lube pressure. The B809A generator set engine safety circuit incorporates a seven-second time delay before activation in order to prevent false alarms or unnecessary shutdowns. This delay allows the engine to stabilize and ensures that the low lube pressure condition is consistent before triggering the safety circuit. By incorporating this time delay, the engine is protected from potential damage or failure caused by insufficient lubrication.

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50.

What action occurs when the B809A generator set AC card senses an AC supply fault?
- A.
  
  Only generator output stops
- B.
  
  Only the AC contactor opens
- C.
  
  AC supply warning light illuminates
- D.
  
  AC contactor opens and generator output stops
Correct Answer
D. AC contactor opens and generator output stops

Explanation
When the B809A generator set AC card senses an AC supply fault, the AC contactor opens and the generator output stops. This means that the AC contactor, which is responsible for controlling the flow of electricity to the generator, opens or disconnects the circuit. As a result, the generator stops producing electrical output. This action is taken to protect the system from any potential damage or danger caused by the AC supply fault.

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Current Version
Mar 20, 2023

Quiz Edited by
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Dec 13, 2013

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2A672 Volume 1 Quiz

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You are driving on the flight line and notice a -86D power unit with all the fault lights on. You try to reset S23, but the lights stay on. What is a probable cause of this trouble?

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What contacts on the annunciator card of the B809A generator set control the alternating current (AC) power input to the voltage regulator?

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What B809A generator set engine safety circuit incorporates a seven-second time delay before activation?

What action occurs when the B809A generator set AC card senses an AC supply fault?