Motor And Motor Control Circuits And Special Purpose Systems
This volume covers the different aspect of motors and motors controls, electrical procudures used in hazardous locations, applications of special equipment, cathod protection for corrosion control, and alarms systems.
Questions and Answers
- 1.
In a DC motor, how are coil ends from the amature winding attached to the riser?
- A.
Welded
- B.
Wedge
- C.
Soldered
- D.
Brazed
Correct Answer
C. SolderedExplanation
The coil ends from the amature winding in a DC motor are attached to the riser by soldering them together. Soldering is a process in which a metal alloy with a low melting point is used to join two or more metal surfaces. In this case, soldering is used to create a strong and reliable connection between the coil ends and the riser, ensuring proper electrical conductivity and mechanical stability.Rate this question:
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- 2.
The DC motor with the highest starting torque is the
- A.
Series motor
- B.
Shunt motor
- C.
Universal motor
- D.
Compound motor
Correct Answer
A. Series motorExplanation
The series motor has the highest starting torque because it has a high starting current due to its field winding being in series with the armature winding. This high starting current produces a strong magnetic field, resulting in a high torque at startup. Additionally, the series motor has a characteristic of decreasing speed as the load increases, allowing it to maintain a high torque even under heavy loads.Rate this question:
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- 3.
The DC shunt motor connects the field coils and armature in
- A.
Series
- B.
Parallel
- C.
Series-parallel
- D.
Parallel-series
Correct Answer
B. ParallelExplanation
The DC shunt motor connects the field coils and armature in parallel. In a parallel connection, the field coils and armature are connected side by side, allowing the current to flow independently through each component. This configuration allows for independent control of the field current and armature current, making the motor suitable for applications that require variable speed control.Rate this question:
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- 4.
What part of a three-phase motor is connected to the supply voltage?
- A.
Centrifugal switch
- B.
Base
- C.
Rotor
- D.
Stator
Correct Answer
D. StatorExplanation
The stator is the part of a three-phase motor that is connected to the supply voltage. It is the stationary component of the motor and contains the coils of wire that create a rotating magnetic field when energized by the supply voltage. The rotating magnetic field interacts with the rotor, causing it to turn and drive the motor's mechanical load. The stator is responsible for generating the magnetic field necessary for the motor's operation.Rate this question:
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- 5.
The component of a three-phase motor connected to the load is the
- A.
Amature
- B.
End bell
- C.
Rotor
- D.
Stator
Correct Answer
C. RotorExplanation
The rotor is the component of a three-phase motor that is connected to the load. It is the rotating part of the motor that converts electrical energy into mechanical energy. The stator, on the other hand, is the stationary part of the motor that houses the windings. The end bell is a part of the motor that covers and protects the rotor and stator. The armature is a component found in DC motors, not three-phase motors. Therefore, the correct answer is the rotor.Rate this question:
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- 6.
The magnetic field of a three-phase motor rotor is caused by
- A.
Resistance in the squirrel cage
- B.
Current flow in the rotor
- C.
Impedance of the stator
- D.
Voltage in the end bells
Correct Answer
B. Current flow in the rotorExplanation
The magnetic field of a three-phase motor rotor is caused by the current flow in the rotor. When electrical current flows through the rotor windings, it creates a magnetic field. This magnetic field interacts with the stator's magnetic field, causing the rotor to rotate. The resistance in the squirrel cage, impedance of the stator, and voltage in the end bells are not directly responsible for generating the magnetic field in the rotor.Rate this question:
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- 7.
Which motor would have the highest rpm if each were connected to the same power supply?
- A.
4-pole motor
- B.
6-pole motor
- C.
12-pole motor
- D.
24-pole motor
Correct Answer
A. 4-pole motorExplanation
The 4-pole motor would have the highest rpm if each were connected to the same power supply. This is because the number of poles in a motor is inversely proportional to its speed. A motor with fewer poles will have a higher rotational speed compared to a motor with more poles when connected to the same power supply. Therefore, the 4-pole motor will have the highest rpm among the given options.Rate this question:
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- 8.
The internal winding of all three-phase motors are
- A.
Either connected in series or parallel
- B.
Either wye or delta connected
- C.
Are always in series with the supply
- D.
Are always in parallel with the load
Correct Answer
B. Either wye or delta connectedExplanation
The internal winding of all three-phase motors can be connected in either a wye or delta configuration. This means that the windings can be connected in a star (wye) or triangle (delta) pattern. The choice of connection depends on the motor design and the desired performance characteristics. Both configurations have their advantages and disadvantages, and the selection is made based on factors such as motor efficiency, starting torque, and voltage requirements.Rate this question:
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- 9.
The motor that requires some starting means is the
- A.
Universal motor
- B.
DC shunt motor
- C.
Three-phase AC motor
- D.
Single-phase AC motor
Correct Answer
D. Single-phase AC motorExplanation
A single-phase AC motor requires some starting means because it has a single alternating current phase, which produces a pulsating torque that is not sufficient to start the motor on its own. Starting means such as a capacitor or a centrifugal switch are used to provide an initial boost to the motor's starting torque. This helps the motor overcome the initial inertia and start rotating smoothly. In contrast, three-phase AC motors do not require additional starting means as they have a balanced three-phase power supply, which generates a rotating magnetic field that provides enough starting torque.Rate this question:
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- 10.
A centrifugal switch is used in a single-phase motor to
- A.
Engage the power leads
- B.
De-energize the start windings
- C.
Engage the run windings
- D.
De-energize the field windings
Correct Answer
B. De-energize the start windingsExplanation
A centrifugal switch is used in a single-phase motor to de-energize the start windings. This is because the start windings are only needed during the starting phase of the motor, and once the motor reaches a certain speed, the centrifugal switch is triggered to disconnect the start windings. This prevents the start windings from overheating and causing damage to the motor. By de-energizing the start windings, the motor can smoothly transition to using the run windings for continuous operation.Rate this question:
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- 11.
The squirrel-cage winding has high-inductive reactance and is placed beneath the
- A.
Left endbell
- B.
Right endbell
- C.
Housing section
- D.
Wound rotor section
Correct Answer
D. Wound rotor sectionExplanation
The squirrel-cage winding is placed in the wound rotor section. This is because the squirrel-cage winding has high-inductive reactance, which helps in controlling the speed and torque characteristics of the motor. Placing it in the wound rotor section allows for easy access to the winding and ensures efficient functioning of the motor.Rate this question:
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- 12.
What should you connect to operate a single-phase dual-voltage motor on high voltage?
- A.
Run windings in series
- B.
Run windings in delta
- C.
Start windings in parallel
- D.
Start windings in wye
Correct Answer
A. Run windings in seriesExplanation
To operate a single-phase dual-voltage motor on high voltage, the run windings should be connected in series. This configuration allows the motor to handle the higher voltage effectively. When the run windings are connected in series, the voltage across each winding is divided, reducing the overall voltage and allowing the motor to operate at the desired high voltage. This series connection ensures that the windings work together to generate the required magnetic field and enable the motor to run smoothly at high voltage.Rate this question:
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- 13.
Normally, an across-the-line motor control incoporate some type of
- A.
Lightning protection
- B.
Motor overcurrent protection
- C.
Motor speed control
- D.
Frequency control
Correct Answer
B. Motor overcurrent protectionExplanation
An across-the-line motor control typically includes motor overcurrent protection. This is important because it helps prevent damage to the motor and other equipment in the event of excessive current flow. Overcurrent protection devices, such as fuses or circuit breakers, are used to detect and interrupt excessive current, thereby safeguarding the motor from potential damage.Rate this question:
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- 14.
How many basic types of across-the-line motor control are there?
- A.
Five
- B.
Four
- C.
Three
- D.
Two
Correct Answer
D. TwoExplanation
There are two basic types of across-the-line motor control.Rate this question:
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- 15.
The basic types of overload relays are
- A.
Mechancial and magnetic
- B.
Undervoltage and overcurrent
- C.
Thermal and magnetic
- D.
Single-and three-phase
Correct Answer
C. Thermal and magneticExplanation
The basic types of overload relays are thermal and magnetic. Thermal overload relays are designed to protect motors from overheating by monitoring the motor's current and temperature. They use a bimetallic strip that bends and activates a switch when the temperature exceeds a certain threshold. Magnetic overload relays, on the other hand, are used to protect motors from excessive current. They use a magnetic coil that generates a magnetic field when the current exceeds a set value, causing the relay to trip and disconnect the motor.Rate this question:
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- 16.
The method used to open the contacts on an across-the -line magnetic controller are
- A.
Magnetic and thermal
- B.
Spring tension and gravity
- C.
Thermal and hydraulic
- D.
Metallic and magnetic
Correct Answer
B. Spring tension and gravityExplanation
The method used to open the contacts on an across-the-line magnetic controller is spring tension and gravity. This means that the contacts are held closed by the force of a spring, and they open when the spring tension is released and gravity pulls the contacts apart. This method allows for a reliable and efficient way to control the flow of electricity in the controller.Rate this question:
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- 17.
What type of motor enclosure is designed to prevent liquids or solids from entering it except at indirect angles?
- A.
Open
- B.
Splash-proof
- C.
Drip-proof
- D.
Explosive-proof
Correct Answer
B. Splash-proofExplanation
A splash-proof motor enclosure is designed to prevent liquids or solids from entering the motor, except at indirect angles. This means that the enclosure is constructed in a way that it can withstand splashes or sprays of liquid, such as water, without allowing them to directly enter the motor. It provides a level of protection against moisture and debris, making it suitable for environments where there is a possibility of splashing or indirect exposure to liquids.Rate this question:
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- 18.
What should be your first check on a motor that seems to be overheating?
- A.
Wire size
- B.
Shorted winding
- C.
Ventilation
- D.
Load too big for the motor
Correct Answer
C. VentilationExplanation
The first check on a motor that seems to be overheating should be ventilation. Ventilation refers to the proper airflow around the motor, which helps dissipate heat and prevent overheating. If the motor is not receiving adequate ventilation, it can lead to excessive heat buildup and potential damage to the motor. Therefore, checking the ventilation is crucial in troubleshooting an overheating motor.Rate this question:
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- 19.
The end ply of a motor should not exceed
- A.
1/8 of an inch
- B.
1/16 of an inch
- C.
1/32 of an inch
- D.
1/64 of an inch
Correct Answer
D. 1/64 of an inchExplanation
The end ply of a motor should not exceed 1/64 of an inch because exceeding this limit could result in improper functioning and damage to the motor. Maintaining a small end ply ensures that the motor operates smoothly and efficiently, without any unnecessary friction or wear.Rate this question:
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- 20.
An indication of an open rotor in a squirrel-cage motor is
- A.
Excessive sparking
- B.
The motor speeding up
- C.
Excessive noise and heat
- D.
The motor slowing down under load
Correct Answer
D. The motor slowing down under loadExplanation
When a squirrel-cage motor has an open rotor, it means that one or more of the conductive bars in the rotor are broken or disconnected. This results in a decrease in the motor's torque production, causing it to slow down under load. As the rotor is unable to generate enough magnetic field to maintain the required speed, the motor's performance is affected, leading to a decrease in its rotational speed.Rate this question:
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- 21.
The conductor common to both the starting and holding circuits is connected to
- A.
L1
- B.
T1
- C.
L2
- D.
T2
Correct Answer
A. L1Explanation
The conductor common to both the starting and holding circuits is connected to L1. This means that the starting and holding circuits share a common connection with the L1 phase. This connection allows for the flow of current between the two circuits, ensuring that the motor can start and continue running smoothly.Rate this question:
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- 22.
A motor that operates slowly may have a
- A.
Deficient voltage supply
- B.
Ventilation problem
- C.
Bad conductor
- D.
Blown fuse
Correct Answer
A. Deficient voltage supplyExplanation
A motor that operates slowly may have a deficient voltage supply. When the voltage supply is insufficient, it can result in a decrease in the motor's speed and performance. This can occur due to various reasons such as low power supply, damaged wiring, or loose connections. In such cases, the motor may not receive enough power to operate at its optimal speed, leading to a slower operation.Rate this question:
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- 23.
Motor voltage must be within what percent of the voltage rating
- A.
1
- B.
3
- C.
5
- D.
10
Correct Answer
D. 10Explanation
The motor voltage must be within 10% of the voltage rating. This means that the actual voltage supplied to the motor should not deviate more than 10% from the rated voltage. This is important because exceeding this range can lead to inefficient performance, overheating, and potential damage to the motor. Therefore, it is crucial to ensure that the motor is operated within this specified voltage range to maintain its optimal functioning and longevity.Rate this question:
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- 24.
A woodworking shop would constitute what class of electrical hazard?
- A.
Class 1
- B.
Class 2
- C.
Class 3
- D.
Class 4
Correct Answer
C. Class 3Explanation
A woodworking shop would constitute a Class 3 electrical hazard because Class 3 hazards involve equipment that operates at extra-low voltage, typically less than 50 volts. In a woodworking shop, power tools and machinery often operate at low voltages to reduce the risk of electrical shock. Class 3 hazards are considered less dangerous compared to higher voltage classes, but proper safety precautions should still be followed to prevent accidents and injuries.Rate this question:
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- 25.
Electrical equipment used in class 1 locations must be
- A.
Sparkproof
- B.
Dustproof
- C.
Waterproof
- D.
Explosion-proof
Correct Answer
D. Explosion-proofExplanation
Electrical equipment used in class 1 locations must be explosion-proof because these locations have a high risk of explosive atmospheres due to the presence of flammable gases, vapors, or liquids. Explosion-proof equipment is designed to contain any potential sparks or explosions within its enclosure, preventing them from igniting the surrounding hazardous atmosphere. This ensures the safety of personnel and property in such environments by minimizing the risk of explosions and subsequent fires.Rate this question:
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- 26.
Sparkproof electrical equipment must be used in what class lacations?
- A.
Class 1
- B.
Class 2
- C.
Class 3
- D.
Class 4
Correct Answer
C. Class 3Explanation
Sparkproof electrical equipment must be used in Class 3 locations. Class 3 locations are areas where easily ignitable fibers or materials producing combustible flyings are handled, manufactured, or used. The use of sparkproof electrical equipment is necessary in these locations to prevent the ignition of these materials and reduce the risk of fire. Class 1 locations involve flammable gases or vapors, Class 2 locations involve combustible dust, and Class 4 locations involve easily ignitable materials.Rate this question:
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- 27.
To prevent explosive materials from passing from one part of an explosion-proof conduit system to another, you should use
- A.
Epoxy
- B.
Cork seals
- C.
Rubber seals
- D.
Sealing compound
Correct Answer
D. Sealing compoundExplanation
To prevent explosive materials from passing from one part of an explosion-proof conduit system to another, a sealing compound should be used. A sealing compound is a substance that is applied to the joints and connections of the conduit system to create a tight seal and prevent the passage of explosive materials. It is specifically designed to withstand the pressure and temperature changes that may occur during an explosion, ensuring the integrity of the conduit system and minimizing the risk of explosions spreading.Rate this question:
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- 28.
Before working on an electrical system, you always should
- A.
Use approve tools
- B.
Deenergize the power to the circuit
- C.
Disassemble the enclosures
- D.
Wear rubber protective equipment
Correct Answer
B. Deenergize the power to the circuitExplanation
Before working on an electrical system, it is important to deenergize the power to the circuit. This ensures that there is no electrical current flowing through the system, reducing the risk of electric shock or injury. Deenergizing the power involves turning off the power source, such as flipping a switch or unplugging the device. This step is crucial for the safety of the person working on the system and prevents any potential damage to the equipment or surrounding areas.Rate this question:
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- 29.
When you work in a class 1 hazardous location, you should use all the equipment listed below except
- A.
Class 1 flashlights or laterns
- B.
Non-sparking metal handtools
- C.
SO flexible hard-service cord
- D.
Battery-power test equipment
Correct Answer
B. Non-sparking metal handtoolsExplanation
When working in a class 1 hazardous location, it is important to use equipment that is safe and does not create sparks, as sparks can ignite flammable substances present in the environment. Class 1 flashlights or lanterns are designed to be safe for use in these locations. SO flexible hard-service cord and battery-powered test equipment are also safe options as they do not generate sparks. However, non-sparking metal handtools are not recommended as they can potentially create sparks, making them unsafe for use in a hazardous location.Rate this question:
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- 30.
If work must be done on equipment exposed to hazardous material, the equipment should be
- A.
Painted
- B.
Grounded
- C.
Cleaned and tagged
- D.
Removed and taken to a lab area
Correct Answer
C. Cleaned and taggedExplanation
When work needs to be done on equipment exposed to hazardous material, it is important to ensure the safety of the workers. Cleaning the equipment helps to remove any hazardous material residue, reducing the risk of exposure. Tagging the equipment after cleaning is necessary to indicate that it has been cleaned and is safe to work on. This helps to prevent any accidental use of contaminated equipment. Therefore, cleaning and tagging the equipment is the appropriate course of action in this situation.Rate this question:
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- 31.
Emergency lights are powered by
- A.
AC power
- B.
DC power
- C.
Generators
- D.
Transformers rectifiers
Correct Answer
B. DC powerExplanation
Emergency lights are powered by DC power because they need to be able to function even when there is a power outage. DC power, which stands for direct current, provides a continuous flow of electricity in one direction. This ensures that the emergency lights can stay on for an extended period of time without relying on the fluctuating AC power supply. Additionally, using DC power allows for more efficient and reliable operation of the emergency lights, making them a suitable choice for emergency situations.Rate this question:
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- 32.
The bulb normall used with incandescent emergency lights is a
- A.
20-watt fluorescent tube
- B.
40-watt, 120-volt incandescent bulb
- C.
25-watt, 6-volt sealed-beam lamp
- D.
250-watt, 120-volt HID bulb
Correct Answer
C. 25-watt, 6-volt sealed-beam lampExplanation
The correct answer is 25-watt, 6-volt sealed-beam lamp. Incandescent emergency lights typically use a 25-watt, 6-volt sealed-beam lamp because it provides a sufficient amount of light for emergency situations. A sealed-beam lamp is a type of incandescent lamp that is sealed and contains both the filament and reflector in one unit. It is commonly used in emergency lights due to its durability and ability to withstand harsh conditions. The 6-volt rating is important because it matches the voltage supplied by the emergency light's battery.Rate this question:
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- 33.
According to the NEC, the wiring for emergency lighting system must be
- A.
Any branch circuit of the proper size
- B.
Run in conduit
- C.
Off at least No.6 wire or equivalent
- D.
Independent of the regular wiring used for appliances
Correct Answer
D. Independent of the regular wiring used for appliancesExplanation
The correct answer is "independent of the regular wiring used for appliances". This means that the wiring for the emergency lighting system should not be connected or dependent on the regular wiring used for appliances. It should be a separate and dedicated wiring system specifically for the emergency lighting. This ensures that the emergency lighting system will have its own power source and will not be affected or compromised by any issues with the regular wiring or appliances in the building.Rate this question:
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- 34.
How often should a total discharge of emergency -light batteries and recharge be done?
- A.
Yearly
- B.
Every 6 months
- C.
Monthly
- D.
Weekly
Correct Answer
B. Every 6 monthsExplanation
The correct answer is Every 6 months. It is important to regularly discharge and recharge emergency light batteries to ensure their proper functioning during an emergency. Doing this every 6 months helps to maintain the battery's capacity and prolong its lifespan. This regular maintenance schedule ensures that the batteries are always ready to provide adequate lighting when needed.Rate this question:
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- 35.
The electric range produces heat by
- A.
Producing voltage to a switch
- B.
Producing current to a switch
- C.
Passing current through a resistor
- D.
Passing voltage through a resistor
Correct Answer
C. Passing current through a resistorExplanation
The electric range produces heat by passing current through a resistor. When current flows through a resistor, it encounters resistance, which causes the electrons to collide with the atoms in the resistor material. This collision generates heat energy, which is then used to heat the range.Rate this question:
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- 36.
What is the most desirable water heater temperature control setting for general purposes?
- A.
110 F
- B.
150 F
- C.
180 F
- D.
230 F
Correct Answer
B. 150 FExplanation
The most desirable water heater temperature control setting for general purposes is 150°F. This temperature is considered safe and efficient for most household needs. It is hot enough to provide comfortable hot water for bathing and cleaning, while also minimizing the risk of scalding. Additionally, setting the water heater at 150°F can help prevent the growth of harmful bacteria, such as Legionella, in the water system.Rate this question:
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- 37.
The most common appliance repairs made are to motors, switches, and
- A.
Heating elements
- B.
Receptacles
- C.
Circuit breakers
- D.
Timers
Correct Answer
A. Heating elementsExplanation
The most common appliance repairs made are to motors, switches, and heating elements. Heating elements are frequently repaired because they are a crucial component in appliances such as ovens, toasters, and dryers. Over time, heating elements can wear out or become damaged, leading to a decrease in their efficiency or complete malfunction. Therefore, it is not surprising that heating elements are among the most commonly repaired parts in appliances.Rate this question:
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- 38.
What type of grease should you use when you lubricate switches and controls in appliances?
- A.
Thin
- B.
Thick
- C.
Oxide
- D.
Nonoxide
Correct Answer
D. NonoxideExplanation
When lubricating switches and controls in appliances, it is important to use a nonoxide grease. This type of grease is specifically designed to prevent the formation of oxides, which can cause corrosion and hinder the smooth functioning of the switches and controls. By using a nonoxide grease, you can ensure that the switches and controls remain properly lubricated, reducing friction and enhancing their overall performance.Rate this question:
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- 39.
What is the first step in troubleshooting an appliance
- A.
Power check
- B.
Visual inspection
- C.
Operational check
- D.
Disassemble the appliance
Correct Answer
B. Visual inspectionExplanation
The first step in troubleshooting an appliance is to perform a visual inspection. This involves examining the appliance for any obvious signs of damage, such as loose connections, frayed wires, or burnt components. By visually inspecting the appliance, you can identify any visible issues that may be causing the problem. This step is important as it helps to narrow down the possible causes of the appliance malfunction and guides further troubleshooting steps.Rate this question:
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- 40.
To prevent others from tampering with switches, you will
- A.
Mark them
- B.
Turn them off
- C.
Deenergize them
- D.
Lock and tag them
Correct Answer
D. Lock and tag themExplanation
To prevent others from tampering with switches, it is necessary to lock and tag them. This ensures that unauthorized individuals are unable to access or manipulate the switches, thereby maintaining safety and security. Locking the switches prevents physical access, while tagging provides a clear indication that the switches are locked and should not be touched. This combination of measures is an effective way to prevent tampering and promote safety in switch usage.Rate this question:
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- 41.
If you check a heating element and the Ohmmeter reads "0" Ohms, the element is
- A.
Good
- B.
Open
- C.
Shorted
- D.
Grounded
Correct Answer
A. GoodExplanation
If the Ohmmeter reads "0" Ohms when checking a heating element, it indicates that there is continuity in the circuit and the element is functioning properly. A reading of "0" Ohms means that there is no resistance in the element, which is what we would expect from a good heating element.Rate this question:
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- 42.
A signal head may have a maximum of how many signal faces?
- A.
3
- B.
5
- C.
7
- D.
9
Correct Answer
B. 5Explanation
A signal head refers to the device that displays traffic signals. It typically consists of multiple signal faces, each representing a different direction or type of traffic movement. The question asks for the maximum number of signal faces that a signal head can have. The correct answer is 5, indicating that a signal head can display up to 5 different signal faces to control traffic flow effectively.Rate this question:
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- 43.
The most common type of detectors for traffic controls are
- A.
Pressure and heat
- B.
Heat and infra red
- C.
Infra red and loop
- D.
Pressure and loop
Correct Answer
D. Pressure and loopExplanation
The correct answer is pressure and loop. Pressure detectors are commonly used in traffic controls to detect the presence of vehicles by measuring the pressure exerted on the road surface. Loop detectors, on the other hand, use electromagnetic induction to detect vehicles by sensing changes in the magnetic field caused by the presence of metal. Both pressure and loop detectors are reliable and widely used in traffic control systems to monitor and manage traffic flow efficiently.Rate this question:
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- 44.
Which of the following do you use on a traffic control system?
- A.
AM and FM
- B.
AM and MED
- C.
AM
- D.
FM
Correct Answer
D. FMExplanation
FM (Frequency Modulation) is used on a traffic control system. AM (Amplitude Modulation) is not used, and neither is MED (which is not a recognized abbreviation in this context). FM is commonly used in traffic control systems to transmit information and signals, as it provides better sound quality and is less susceptible to interference compared to AM.Rate this question:
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- 45.
The controller operates loop and lead-in system whose total inductance is between
- A.
10 and 20 microhenries
- B.
20 and 70 microhenries
- C.
70 and 100 microhenries
- D.
100 and 170 microhenries
Correct Answer
B. 20 and 70 microhenriesExplanation
The controller operates a loop and lead-in system, which implies that it requires a specific range of inductance to function properly. The correct answer states that the total inductance of the loop and lead-in system is between 20 and 70 microhenries. This suggests that any inductance value below 20 or above 70 microhenries would not be suitable for the controller's operation.Rate this question:
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- 46.
Most repairs made in the controller cabinet of a traffic control system are made by replacing
- A.
Burned-out bulbs
- B.
A module or curcuit board
- C.
Crimp-on spade connectors
- D.
The resistors for the detector loops
Correct Answer
B. A module or curcuit boardExplanation
The correct answer is a module or circuit board. When repairs are needed in the controller cabinet of a traffic control system, it is common to replace a malfunctioning module or circuit board. This is because these components are crucial for the proper functioning of the system and are more likely to fail compared to other components like burned-out bulbs or crimp-on spade connectors. Replacing the faulty module or circuit board ensures that the traffic control system can continue to operate efficiently.Rate this question:
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- 47.
What are te standard size for signal lenses?
- A.
2" and 4" nominal in diameter
- B.
4" and 6" nominal in diameter
- C.
8" and 12" nominal in diameter
- D.
6" and 12" nominal in diameter
Correct Answer
C. 8" and 12" nominal in diameterExplanation
The standard size for signal lenses is 8" and 12" nominal in diameter.Rate this question:
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- 48.
What is the minimum mounting clearance required for the signal head?
- A.
12 feet
- B.
15 feet
- C.
18 feet
- D.
21 feet
Correct Answer
B. 15 feetExplanation
The minimum mounting clearance required for the signal head is 15 feet. This means that there should be a vertical distance of at least 15 feet between the ground and the signal head when it is mounted. This clearance is necessary to ensure that the signal head is visible and unobstructed by any objects or structures, allowing drivers and pedestrians to easily see and interpret the signals. Mounting the signal head at a lower height may lead to reduced visibility and potential safety hazards on the road.Rate this question:
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- 49.
The purpose of the motor on a siren for a base warning system is to rotate the siren
- A.
A quarter of a turn and stop
- B.
A quarter of a turn and return to the starting point
- C.
180 degree
- D.
360 degree
Correct Answer
D. 360 degreeExplanation
The purpose of the motor on a siren for a base warning system is to rotate the siren 360 degrees. This allows the siren to emit sound in all directions, ensuring that the warning is heard by as many people as possible. A full rotation also helps to create a sense of urgency and grab attention.Rate this question:
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- 50.
Which organization is responsible for turning on the base warning siren?
- A.
BCE
- B.
Command post
- C.
Wing commander
- D.
Base fire department
Correct Answer
B. Command postExplanation
The command post is responsible for turning on the base warning siren. This is because the command post is the central hub of communication and coordination on a military base, and they are responsible for issuing alerts and warnings in emergency situations. The base warning siren is a crucial tool for alerting personnel on the base of potential threats or dangers, and it is the command post's responsibility to activate it when necessary.Rate this question:
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