Source text. Published from the recorded source PDF for NEETS Module 3: Circuit Protection, Control, and Measurement.
INDEX-1
Module 3 Index
A Ammeters, 1-16 to 1-23 connected in series, 1-17, 1-18 effect on circuit being measured, 1-18 ranges, 1-19 to 1-23 range selection, 1-23, 1-24 safety precautions, 1-24, 1-25 sensitivity, 1-19 Automatic switch, 3-5 B Basic meter movements, 1-4 to 1-16 compass and alternating current, 1-10, 1-11 compass and conducting wire, 1-4 to 1-6 damping, 1-12, 1-13 electrodynamic meter movement, 1-13 hot-wire and thermocouple meter movements 1-15, 1-16 indicating alternating current, 1-13 moving vane meter movements, 1-14 permanent-magnet moving-coil movement, 1-6 to 1-10 rectifier for ac measurement, 1-11, 1-12 C Cartridge fuse, 2-6, 2-7 Circuit breakers, 2-20 to 2-29 magnetic trip element, 2-23, 2-24 maintenance, 2-28, 2-29 physical types, 2-26, 2-27 thermal-magnetic trip element, 2-24, 2-25 thermal trip element, 2-23, 2-24 time delay rating, 2-26 trip-free/nontrip free, 2-25, 2-26 Circuit control devices, 3-2 to 3-31 maintenance and replacement of switches, 3-15 to 3-18 relays, 3-22 to 3-27 solenoids, 3-19 to 3-22 switch ratings, 3-15 switch types, 3-4 to 3-16 Circuit measurement, 1-2 to 1-58 ammeters, 1-16 to 1-24 basic meter movements 1-4 to 1-16 meters, others, 1-47 to 1-56 multimeter, 1-40 to 1-47 ohmmeter, 1-32 to 1-40 voltmeters, 1-24 to 1-32 Circuit protection, 2-2 to 2-29 checking and replacement of fuses, 2-15 to 2-19 circuit breaker maintenance, 2-28, 2-29 circuit breakers, 2-20 to 2-29 fuseholders, 2-13 to 2-15 fuse ratings, 2-8 to 2-10 fuse types, 2-6 to 2-8 identification of fuses, 2-10 to 2-13 Commercial designation, fuses, 2-12 to 2-13 new, 2-13 old, 2-12, 2-13 Compass and alternating current, 1-10, 1-11 Compass and conducting wire, 1-4 to 1-6 Cross reference of military and commercial fuse designations, AIV-l, AIV-2 Current rating, fuse, 2-8 D Damping, 1-12, 1-13 E Electrodynamic meter movement, 1-13 F Frequency meters, 1-50 to 1-53 moving-disk, 1-52, 1-53 vibrating-reed, 1-50 Fuseholders, 2-13 to 2-15 clip-type, 2-14 post-type, 2-14 Fuses, 2-4 to 2-20 checking and replacement of, 2-15 to 2-19 identification of, 2-10 to 2-13 ratings, 2-8 to 2-10 INDEX-2 Fuses—Continued types, 2-6 to 2-8 G Glossary, AI-1 to AI-3 H Hook-on type voltameter, 1-47 Hot-wire and thermocouple meter movements, 1-15, 1-16 I In-circuit meters, 1-4 Indicating alternating current, 1-13 L Laws of exponents, AII-1, AII-2 M Maintenance and replacement of switches, 3-15 to 3-18 checking switches, 3-15 to 3-18 preventive maintenance of switches, 3-18 replacement of switches, 3-17, 3-18 Manual switches, 3-5 Megohmmeter, 1-38 to 1-40 safety precautions, 1-39 using, 1-39 Meter movements, basic, 1-4 to 1-16 compass and alternating current, 1-10, 1-11 compass and conducting wire, 1-4 to 1-6 damping, 1-12, 1-13 electrodynamic meter movement, 1-13 hot-wire and thermocouple meter movements, 1-15, 1-16 indicating alternating current, 1-13 moving-vane meter movements, 1-14 permanent-magnet moving-coil 1-6 to 1-10 rectifier for ac measurement, 1-11, 1-12 Military designation, fuses, 2-10 to 2-12 new, 2-11, 2-12 old, 2-10, 2-11 Moving-disk frequency meter, 1-52, 1-53 Moving-vane meter movements, 1-14 Multicontact switches, 3-5 to 3-7 Multimeter, 1-40 to 1-48 function switches, 1-41 multimeter safety precautions, 1-46, 1-47 parallax error, 1-43 to 1-46 scales, 1-41 to 1-43 O Ohmmeters, 1-33 to 1-41 ranges, 1-34 to 1-36 safety precautions, 1-37, 1-38 shunt ohmmeter, 1-36, 1-37 using, 1-33, 1-34 Out-of-circuit meters, 1-4 P Permanent-magnet moving-coil movement, 1-6 to 1-10 Plug-type fuses, 2-6 R Ratings, fuse, 2-8 to 2-10 current rating, 2-8 time delay rating, 2-8 voltage rating, 2-8 Rating, switch, 3-15 current rating, 3-15 voltage rating, 3-15 Rectifier for ac measurement, 1-11, 1-12 Relays, 3-22 to 3-30 Replacement and maintenance of switches, 3-15 to 3-18 Replacement of fuses, 2-17 to 2-19 S Schematic symbols, AIII-1 to AIII-10 Shunt ohmmeter, 1-36, 1-37 Solenoids, 3-19 to 3-22 Switch types, 3-4 to 3-16 automatic, 3-5 manual, 3-5 multicontact, 3-5 to 3-7 INDEX-3 Switch types—Continued other types, 3-11 to 3-15 T Type of fuses, 2-6 to 2-8 cartridge, 2-6, 2-7 plug, 2-6 Time delay rating, fuse, 2-8 V Vibrating-reed frequency meter, 1-50 Voltage rating, fuse, 2-8 Voltmeters, 1-24 to 1-32 connected in parallel, 1-24, 1-25 Voltmeters—Continued electrostatic meter movement, 1-31, 1-32 loading effect, 1-25 to 1-27 making a voltmeter from a current sensitive meter movement, 1-27 ranges, 1-28 to 1-31 safety precautions, 1-32 sensitivity, 1-27 W Watt-hour meter, 1-49, 1-50 Wattmeter, 1-48, 1-49 Assignment Questions Information: The text pages that you are to study are provided at the beginning of the assignment questions.
1
Assignment 1
Textbook assignment: Chapter 1, “Circuit Protection Devices,” pages 1-1 through 1-73. ___________________________________________________________________________________ 1-1. Circuit measurement is used for which of the following purposes? 1. To find the weight of a circuit 2. To increase the power used in a circuit 3. To discover the length and width of a circuit 4. To determine the reason a circuit is not functioning properly 1-2. An in-circuit meter is used for which of the following purposes? 1. To reduce circuit losses 2. To monitor circuit operation 3. To control power to a circuit 4. To prevent circuit overload conditions 1-3. Out-of-circuit meters have which of the following advantages over in circuit meters?
1. They can be used on more than one device 2. They are lighter weight 3. They are more rugged 4. All of the above Figure 1-A.—Compass and wire (dc).
In Answering Questions 1-4 Through
1-6, REFER TO FIGURE 1-A. 1-4. When S1 is closed, the compass needle will align itself in which of the following manners? 1. With magnetic north 2. With geographic north 3. Parallel to the conductor 4. With the magnetic field around the wire 1-5. If the current through the conductor is decreased, what happens to the magnetic field around the conductor? 1. It reverses 2. It decreases 3. It increases 4. It oscillates 1-6. When the current through the conductor decreases, the compass needle will react in which of the following manners?
1. Point more to magnetic north 2. Move farther away from magnetic north 3. Swing back and forth from east to west 4. Vibrate rapidly back and forth around magnetic north 1-7. The d'Arsonval meter movement is based on which of the following principles? 1. Moving vane 2. Electrostatic 3. Electrodynamic 4. Permanent-magnet moving-coil 2 1-8. Current through a meter results in the pointer. In d'Arsonval meter movement, what force produces this deflection? 1. Thermocouple action 2. Electrostatic repulsion 3. Mechanical spring tension 4. The interaction of magnetic fields 1-9. The hairsprings in a d'Arsonval meter movement perform which of the following functions?
1. They keep the pointer in the position of the last indication when current is removed 2. They aid the movement of the pointer when there is current through the meter 3. They make electrical connections to the meter movement 4. All of the above Figure 1-B.Compass and wire (ac).
In Answering Questions 1-10 And 1-11,
Refer To Figure 1-B.
1-10. If the frequency of the ac source is 5 Hz, how will the compass needle react when S1 is closed? 1. It will swing back and forth 2. It will point directly at the wire 3. It will point directly away from the wire 4. It will vibrate rapidly around magnetic north 1-11. If the frequency of the ac source is 200 Hz, how will the compass needle react when S1 is closed? 1. It will swing back and forth 2. It will point directly at the wire 3. It will point directly away from the wire 4. It will vibrate rapidly around magnetic north 1-12. What device allows a d'Arsonval meter movement to measure ac by converting ac to pulsating dc?
1. A pulsator 2. A modulator 3. A rectifier 4. A converter 1-13. What is meant by the term "meter damping"? 1. Moistening the felt pads 2. Smoothing the oscillations of the pointer 3. Preventing excessive current through the coil 4. Compensating for electromagnetic induced interference 1-14. Which of the following methods is used to dampen a meter? 1. Mount the meter in a mu-metal case 2. Install a fuse in one of the input leads 3. Incorporate an airtight chamber containing a van 4. Provide a fluid reservoir and sponge arrangement next to the pads 3 1-15. A d'Arsonval meter movement reacts to which of the following values of voltage?
1. Peak 2. Average 3. Effective 4. Peak-to-peak 1-16. What value of ac is indicated by a meter scale? 1. Peak 2. Average 3. Effective 4. Peak-to-peak 1-17. Which of the following meter movements will measure either ac or dc without the use of a rectifier? 1. GMS 2. d'Arsonval 3. Electrostatic 4. Electrodynamic 1-18. What electrical property is reacted to by the electrodynamic, d'Arsonval, moving- vane, and thermocouple meter movements? 1. Power 2. Current 3. Voltage 4. Resistance 1-19. What electrical property is measured by an ammeter?
1. Power 2. Current 3. Voltage 4. Resistance 1-20. How are ammeters connected in an electrical circuit? 1. In series with the load 2. In parallel with the load 3. In accordance with Lenz's Law 4. In series-parallel with the load 1-21. How does an ammeter affect the circuit being measured? 1. It acts as a resistances in series and lowers the circuit current 2. It acts as a resistance in series and raises the circuit current 3. It acts as a resistance in parallel and lowers the circuit current 4. It acts as a resistance in parallel and raises the circuit current 1-22. How is the effect that an ammeter produces in a circuit kept to a minimum?
1. By using a large resistor in series with the ammeter 2. By using a large capacitor in parallel with the ammeter 3. By ensuring that the meter resistance is low compared to circuit resistance 4. By ensuring that the meter resistance is high compared to circuit resistance 1-23. The ammeter with the greatest sensitivity has which of the following characteristics? 1. The lowest amount of current for full- scale deflection indication 2. The highest amount of current for full- scale deflection indication 3. A low ratio of internal resistance to full-scale deflection indication 4. A high ratio of internal resistance to full-scale deflection indication 1-24. Ammeters measure various ranges through the addition of which of the following components?
1. Shunt resistors in series with the meter movement 2. Shunt resistors in parallel with the meter movement 3. Capacitors in series with the meter movement 4. Capacitors in parallel with the meter movement 4 1-25. What range of an ammeter should you use for an initial measurement? 1. The lowest range 2. The highest range 3. The mid-scale range 1-26. What portion of the ammeter scale should be used to take a final reading? 1. The upper half 2. The lower half 3. The mid-scale portion 4. Anywhere on the meter face 1-27. When, if ever, can you use a dc ammeter to measure ac values?
1. When the ac is high frequency 2. For low values 3. Always 4. Never 1-28. Which of the following safety precautions should be observed prior to connecting an ammeter into a circuit? 1. Switch to the highest range 2. Observe proper dc polarity 3. Deenergize the circuit 4. All of the above 1-29. What electrical property is measured by a voltmeter? 1. Power 2. Current 3. Voltage 4. Resistance 1-30. A voltmeter should be connected in an electrical circuit in what manner? 1. In series with the load 2. In parallel with the load 3. In accordance with Lenz's Law 4. In series-parallel with the load 1-31. A voltmeter has an effect on the circuit being measured; what is this effect called?
1. Loading 2. Damping 3. Rectification 4. Eddy-current drag 1-32. To keep the effect of a voltmeter on a circuit to a minimum, the internal resistance of the voltmeter must have which of the following relationships to the circuit load? 1. Equal to 2. Lower than 3. Higher than 4. In proportion to 1-33. Which of the following types of meters can be made from a current sensitive meter movement? 1. Ammeter 2. Ohmmeter 3. Voltmeter 4. Each of the above 1-34. A voltmeter has a high sensitivity when it has which of the following characteristics?
1. Low deflection indication 2. High deflection indication 3. Low ratio of internal resistance to full- scale deflection indication 4. High ratio of internal resistance to full-scale deflection indication 1-35. Which of the following configurations extends the range of a voltmeter? 1. A resistor in series with the meter movement 2. A resistor in parallel with the meter movement 3. A capacitor in series with the meter movement 4. A capacitor in parallel with the meter movement 5 1-36. What voltmeter range should be used for initial measurements?
1. The lowest 2. The highest 3. The mid-scale 1-37. The electrostatic meter movement reacts to which of the following electrical properties? 1. Power 2. Current 3. Voltage 4. Resistance 1-38. Electrostatic meter movements are used to measure which of the following current/voltage values? 1. Low voltage 2. Low current 3. High voltage 4. High current 1-39. Which of the following safety precautions should be observed when a voltmeter is used? 1. Deenergize the circuit before connecting the meter 2. Start with the lowest range of the meter 3. Connect the meter in series with the circuit 4. All of the above 1-40. What electrical property is measured with an ohmmeter?
1. Power 2. Current 3. Voltage 4. Resistance 1-41. An ohmmeter is used to check for which of the following conditions? 1. Continuity 2. Overheating 3. Overcurrent 4. Undercurrent 1-42. How should an ohmmeter be connected in an electrical circuit? 1. In series with the load 2. In parallel with the load 3. In parallel with the source 4. In series-parallel with the load 1-43. An ohmmeter can measure different ranges because of the use of which of the following components? 1. Range coils 2. Range resistors 3. Range capacitors 4. Range potentiometers 1-44. What area of an ohmmeter scale should be used when a measurement is taken?
1. Upper half 2. Lower half 3. Mid-scale portion 4. Anywhere on the meter face 1-45. Ohmmeter are classified by type. What are the two types of ohmmeters? 1. Series and shunt 2. Normal and reverse 3. Full- and half-scale 1-46. What is the most obvious differences in the two types of ohmmeters? 1. The ranges of the meters 2. The scales of the meters 3. The power sources of the meters 4. The size of the test leads of the meters 6 1-47. Which of the following safety precautions should be observed when an ohmmeter is used?
1. Always start with the highest scale of the meter 2. Deenergize the circuit before connecting the meter 3. Observe proper polarity 4. All of the above 1-48. Meggers (megohmmeters) are used to measure which of the following quantities? 1. Low voltage 2. High voltage 3. Low resistance 4. High resistance 1-49. When a megger is used to check the insulation of a wire, which of the following indications should be considered normal? 1. ∞ 2. 0 3. 500 V 4. 1000 V 1-50. Which of the following safety precautions should be observed when a megger is used?
1. Do not use a dc megger to measure circuits that are powered by ac 2. Always start with the highest scale selection of the meter 3. Do not touch the meter leads when a measurement is being taken 4. All of the above 1-51. A multimeter can be used to measure which of the following electrical properties? 1. Voltage 2. Current 3. Resistance 4. Each of the above 1-52. The function switch on a multimeter does NOT perform which of the following functions? 1. Selection of the meter range 2. Determination of the proper scale 3. Selection of ac or dc capability 4. Changing of the multimeter from an ammeter to a voltmeter 1-53. One of the problems encountered in building a multimeter is that the meter movement gives different readings for the same values of ac and dc. Which of the following features of a multimeter will solve this problem?
1. A rectifier 2. An ac/dc switch 3. Separate scales for ac and dc 4. A mirror on the face of the meter 1-54. Why is there a mirror on the face of a multimeter? 1. To illuminate the meter face 2. To aid in reducing parallax error 3. To reduce the friction between the pointer and the meter face 4. To compensate for the difference in ac and dc measurements 1-55. If the mirror on the face of a multimeter is used properly, where will the image of the pointer appear? 1. Hidden behind the pointer 2. Barely visible on either side of the pointer 3. Clearly visible to the left of the pointer 4. Clearly visible to the right of the pointer 7 1-56. Which of the following safety precautions does NOT apply to a multimeter?
1. Observe proper dc polarity when measuring dc 2. Deenergize the circuit before connecting the meter 3. Be sure the meter is switched to ac for ac measurements 4. Never apply power to the circuit when measuring voltage with the meter 1-57. If a multimeter has no OFF position, and it is returned to storage, on which of the following positions should the meter be set? 1. +dc; highest voltage range 2. −dc; higher resistance range 3. Ac; highest voltage range 4. Ac; highest current range 1-58. When the current in a conductor is measured without the conductor being disconnected, which of the following meters could be used?
1. Multimeter 2. Hook-on voltameter 3. Induction wattmeter 4. Transformer voltmeter 1-59. Which of the following electrical quantities is measured by a wattmeter? 1. Power 2. Energy 3. Voltage 4. Current 1-60. Which of the following electrical quantities is measured by a watt hour meter? 1. Power 2. Energy 3. Voltage 4. Current 8
Assignment 2
Textbook assignment: Chapter 2, “Circuit Protection Devices,” pages 2-1 through 2-42. _________________________________________________________________________________ 2-1. Circuit protection devices are used for which of the following purposes? 1. To protect people 2. To protect circuits 3. To guard against hazardous conditions 4. All of the above 2-2. Which of the following conditions does NOT require the use of a circuit protection device? 1. Direct short 2. High resistance 3. Excessive current 4. Abnormal heating 2-3. When a point in a circuit, where full system voltage is present, comes in direct contact with the ground or return side of the circuit, which of the following terms applies?
1. Direct short 2. High resistance 3. Excessive current 4. Abnormal heating 2-4. When circuit current increases beyond the designed current carrying capability of the circuit, which of the following terms applies? 1. Direct short 2. High resistance 3. Excessive current 4. Abnormal heating 2-5. If the bearings of a generator were to fail, which of the following circuit conditions would probably occur? 1. Direct short 2. High resistance 3. Excessive current 4. Abnormal heating 2-6. How are circuit protection devices connected to the circuit they are protecting?
1. Alongside 2. In series 3. In parallel 4. In series-parallel 2-7. Which of the following two are circuit protection devices? 1. Electrical plugs and CO 2 cartridges 2. CO 2 cartridges and circuit breakers 3. Fuses and circuit breakers 4. Fuses and electrical plugs
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9 Figure 2-A.—Recognition practice.
In Answering Questions 2-8
Through 2-13, Refer To Figure 2-A.
2-8. Which of the following is the schematic symbol for a fuse? 1. A 2. B 3. F 4. G 2-9. Which of the following is the schematic symbol for a circuit breaker? 1. A 2. B 3. F 4. G 2-10. Which of the following is an illustration of an open cartridge fuse? 1. C 2. D 3. E 4. I 2-11. Which of the following is an illustration of a good cartridge fuse? 1. C 2. D 3. E 4. I 2-12. Which of the following is an illustration of a good plug-type fuse? 1. C 2. D 3. E 4. H 2-13. Which of the following is an illustration of an open plug-type fuse?
1. C 2. D 3. E 4. H 2-14. Which of the following factors is NOT used to rate fuses? 1. Size 2. Current 3. Voltage 4. Time delay 2-15. A fuse current rating has which of the following definitions? 1. The maximum current that can flow through a circuit without causing the circuit to overheat 2. The maximum current that will flow through a circuit if there is a direct short 3. The maximum current that will flow through a fuse without opening the fuse 4. The maximum current that will not "jump" an open fuse 10 2-16. A fuse voltage rating has which of the following definitions?
1. The maximum voltage that can exist in a circuit without causing the circuit to overheat 2. The maximum voltage that can exist in a circuit if there is a direct short 3. The maximum voltage across a fuse that will not cause the fuse to open 4. The maximum voltage across a fuse that will not jump the open fuse _______________________________________
In Answering Questions 2-17
Through 2-19, Match The Time-
Delay Rating Listed In Column B To
The Electrical Device Listed In
Column A. Not All Items In Column
B Will Be Used.
A. Electrical
DEVICES
B. Time-Delay
RATINGS 2-17. Electric motor 1. Fast 2-18. Lighting circuit 2. Delay 2-19. Meter Movement 3. Standard 4. Intermediate _______________________________________ 2-20. What is the voltage rating for a fuse with the designation F03D1R00B? 1. 32 V or less 2. 125 V or less 3. 250 V or less 4. 500 V or less 2-21. What is the current rating for a fuse with the designation F03B0R50B? 1. 1/2 amp 2. 1.5 amp 3. 3 amp 4. 50 amp 2-22. What is the time-delay rating for a fuse with the designation F03A20R0C? 1. Fast 2. Delay 3. Standard 4. Intermediate 2-23. What is the voltage rating for a fuse with the designation F02B250V10AS?
1. 10 V or less 2. 32 V or less 3. 52 V or less 4. 250 V or less 2-24. What is the current rating for a fuse with the designation F03A125V5A? 1. 125 amp 2. 5 amp 3. 3 amp 4. 1/8 amp 2-25. What is the time-delay rating for a fuse with the designation F04C125V2AS? 1. Fast 2. Delay 3. Standard 4. Intermediate 2-26. What is the voltage rating for a fuse with the designation 3AG20125V? 1. 20 V or less 2. 90 V or less 3. 125 V or less 4. 250 V or less 2-27. What is the current rating for a fuse with the designation 3AG1032V?
1. 1 amp 2. 2 amp 3. 3 amp 4. 10 amp 11 2-28. What is the voltage rating for a fuse with the designation AGC5125V? 1. 12 V or less 2. 25 V or less 3. 51 V or less 4. 125 V or less 2-29. What is the current rating for a fuse with the designation AGC2125V? 1. 1 amp 2. 2 amp 3. 3 amp 4. 25 amp 2-30. What is the new military designation for a fuse with the old, military designation F03D1R50B? 1. F03A125V1.5A 2. F02B125V1.5A 3. F03A250V11/2A 4. F03B125V1.5A Figure 2-B.—Fuseholder identification.
In Answering Questions 2-31
Through 2-34, Refer To Figure 2-B.
2-31. What type of fuseholder is shown in figure 2-B(A)? 1. Clip 2. Post 3. Bayonet 4. Spring-loaded 2-32. What type of fuseholder is shown in figure 2-B(B)? 1. Clip 2. Post 3. Bayonet 4. Spring-loaded 2-33. When you use the fuseholder shown in figure 2-B(B), which connector should be connected to the power source? 1. Ground 2. Center 3. Inside 4. Outside 2-34. When you use the fuseholder shown in figure 2-B(B), which connector should be connected to the load? 1. Ground 2. Center 3. Inside 4. Outside 2-35. Which of the following methods will provide an ABSOLUTE determination as to whether or not a fuse is open?
1. A visual inspection 2. A check of the fuse indicator 3. A voltmeter check of the fuse 4. A thermometer check of the temperature of the fuse 2-36. A fuse is removed from a circuit, checked with an ohmmeter, and found to be shorted. What action should be taken? 1. Discard the fuse 2. Check the fuse with a voltmeter 3. Put the fuse back in the circuit 4. Return the fuse to the supply department 2-37. Which of the following methods should be used to check a .002 ampere fuse? 1. Use a megger and place a capacitor in parallel with the fuse 2. Use a megger and place a capacitor in series with the fuse 3. Use an ohmmeter and place a resistor in parallel with the fuse 4. Use an ohmmeter and place a resistor in series with the fuse 12 2-38. What should you use to remove a fuse from a clip-type fuseholder?
1. A scribe 2. A fusepuller 3. A screwdriver 4. A pair of pliers 2-39. Which of the following is a safety precaution to be observed when a fuse is checked? 1. Turn the power off and discharge the circuit before the fuse is removed 2. When you check a fuse with an ohmmeter, be careful to avoid short circuits 3. When you use a voltmeter to check a low current fuse, be careful to avoid opening the fuse by excessive current from the voltmeter 4. All of the above
You Have Found An Open Fuse In A
Piece Of Equipment And Have
Repaired The Casualty. The
Technical Manual For The
Equipment Specifies A Fuse Coded
F02A125V3A. No Fuses With That
Designation Are Available. The
Following Fuses Are Carried By
The Supply System.
A. F03D3R00A
B. 3Ag3250V
C. F02A3R00B
D. Agc3125V
E. F02D3R00C
F. Agc5250V
Figure 2-C.—Fuse replacement problem.
In Answering Questions 2-40
Through 2-46, Use The Information
In Figure 2-C.
2-40. What fuse is a direct replacement? 1. A 2. C 3. D 4. E 2-41. What fuse is the best substitute? 1. A 2. B 3. C 4. F 2-42. What fuse is the second best in the fuseholder substitute? 1. A 2. C 3. E 4. F 2-43. What fuse is unacceptable because the physical size is incorrect? 1. A 2. C 3. E 4. F 2-44. What fuse is unacceptable because of the current rating? 1. B 2. D 3. E 4. F 2-45. What fuse is unacceptable because of the voltage rating? 1. A 2. B 3. C 4. D 13 2-46. What fuse is unacceptable because of the time-delay rating?
1. A 2. C 3. D 4. E 2-47. Before replacing a fuse, you should check for which of the following conditions? 1. Proper fit 2. Proper fuse 3. Both 1 and 2 above 4. Proper input voltage 2-48. Which of the following is NOT a safety precaution to be observed when a fuse is changed? 1. Be sure to "tag out" the fuseholder when you remove the fuse 2. Remove the power from a circuit before removing and replacing a fuse 3. Remove any corrosion from the fuseholder before replacing a fuse 4. Be sure the fuse fits properly in the fuseholder 2-49. When you perform preventive maintenance on fuses, which of the following is NOT a condition you should check?
1. Corrosion 2. Shorted fuse 3. Improper fit 4. Improper fuse 2-50. What is the total number of main components in a circuit breaker? 1. Five 2. Two 3. Three 4. Four 2-51. Which of the following is NOT a type of trip element for a circuit breaker? 1. Thermal 2. Magnetic 3. Mechanical 4. Thermal-magnetic
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14 _______________________________________
In Answering Questions 2-52
Through 2-54, Select From Column
B The Trip Element That Is
Described By The Action Listed In
Column A. Not All Items In Column
B Will Be Used.
A. Actions
B. Trip Elements
2-52. An electromagnet is connected in series with the load 1. Thermal 2-53. A bimetallic strip is heated by the load current 2. Magnetic 2-54. A bimetallic strip is heated by the load current and electromagnet is connected in series with the load 3. Mechanical 4. Thermal-magnetic _______________________________________ 2-55. A circuit breaker that will trip even if the operating mechanism is held ON is known as what type of circuit breaker? 1. Standard 2. Emergency 3. Trip free 4. Nontrip free 2-56. What type of circuit breaker can be overridden if the operating mechanism is held ON?
1. Standard 2. Emergency 3. Trip free 4. Nontrip free 2-57. Which of the following is NOT a time- delay rating for a circuit breaker? 1. Long 2. Short 3. Standard 4. Instantaneous 2-58. Selective tripping is used to cause which of the following circuit breakers to trip when there is an overload? 1. The least expensive 2. The most accessible 3. The smallest current rating 4. The closest to the fault 2-59. Selective tripping is used to accomplish which of the following purposes? 1. To reduce wear and tear on circuit breakers 2. To isolate a faulty circuit without affecting other circuits 3. To simplify the task of resetting the circuit breaker 4. To enable the application of power to emergency circuits during an overload
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15 Figure 2-D.—Power distribution system using selective tripping.
In Answering Questions 2-60
Through 2-62, Refer To Figure 2-D.
2-60. Which of the following circuit breakers should have a long time delay? 1. CB1 2. CB2 3. CB3 4. CB4 2-61. Which of the following circuit breakers should have a short time delay? 1. CB1 2. CB2 3. CB5 4. CB4 2-62. Which of the following circuit breakers should have an instantaneous time delay? 1. CB1 2. CB2 3. CB3 4. CB4 2-63. The following actions must be taken prior to working on a circuit breaker. Arrange these items in the proper sequence, then select the choice below that lists the events in the proper sequence.
A. Tag the power switch B. Obtain the approval of the electrical officer C. Remove power to the circuit breaker D. Check the applicable technical manual 1. A, B, C, D 2. C, B, D, A 3. D, B, C, A 4. B, A, D, C 2-64. Which of the following items is NOT checked during maintenance on a circuit breaker? 1. Input power voltage 2. Operating mechanism smoothness 3. Terminal tightness and corrosion 4. Contact surfaces for pitting 16
Assignment 3
Textbook assignment: Chapter 3, “Circuit Control Devices,” pages 3-1 through 3-73. _________________________________________________________________________________ 3-1. Circuit control devices should NOT be used for which of the following reasons? 1. To adjust the power level of a device 2. To remove power from a malfunctioning device 3. To apply power to a device when work is completed on it 4. To select the function or circuit desired within a device 3-2. Which of the following are types of circuit control devices?
1. Relays 2. Switches 3. Solenoids 4. All of the above _______________________________________
In Answering Questions 3-3
Through 3-5, Match The Schematic
Symbol Shown In Column B To The
Device Listed In Column A.
_______________________________________ 3-6. Which of the following is a manual switch? 1. A light switch 2. A limit switch 3. A thermostat 4. A distributor 3-7. Which of the following is an automatic switch? 1. An ignition switch on a motor vehicle 2. A switch that turns on a light in a refrigerator 3. A channel selector on a television 4. A dial or push button on a telephone 3-8. Control or selection of one or more circuits is a function of which of the following switches? 1. A manual switch 2. An automatic switch 3. A multicontact switch 4. A single contact switch
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17 Figure 3-A.—Switch schematics.
In Answering Questions 3-9
Through 3-15, Refer To Figure 3-A.
Select The Symbol That Represents
The Type Of Switch Stated In Each
Question.
3-9. A single-pole, double-throw switch. 1. A 2. B 3. C 4. D 3-10. A double-pole, double-throw switch. 1. B 2. E 3. G 4. H 3-11. A single-pole, four-throw switch. 1. B 2. D 3. F 4. H 3-12. A double-pole, single-throw switch. 1. B 2. C 3. E 4. H 3-13. A single-pole, single-throw switch. 1. A 2. B 3. C 4. D 3-14. A three-pole, double-throw switch. 1. E 2. F 3. G 4. H 3-15. A single-pole, triple-throw switch. 1. B 2. D 3. E 4. G
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18 Figure 3-B.—Switch schematics.
In Answering Questions 3-16
Through 3-24, Refer To Figure 3-B.
Select The Symbol That Represents
The Type Of Switch Stated In Each
Question.
3-16. A single-pole, single-throw, double- break switch. 1. A 2. C 3. D 4. E 3-17. A double-pole, single-throw, double- break switch. 1. F 2. H 3. I 4. J 3-18. A single-pole, double-throw, single- break switch. 1. A 2. D 3. E 4. F 3-19. A single-pole, double-throw, double- break switch. 1. E 2. F 3. H 4. I 3-20. A double-pole, single-throw, single- break switch. 1. E 2. H 3. I 4. J 3-21. A double-pole, double-throw, double- break switch. 1. B 2. F 3. H 4. I 3-22. A double-pole, double-throw, single- break switch. 1. F 2. H 3. I 4. J 3-23. A rotary switch.
1. C 2. D 3. H 4. I 19 3-24. A wafer switch. 1. D 2. E 3. G 4. H 3-25. A switch actuator is described by which of the following terms? 1. Momentary 2. Two-position 3. Toggle 4. Four-position 3-26. What is the maximum number of different single-pole, single throw switch positions possible? 1. One 2. Two 3. Three 4. Four 3-27. What is the maximum number of different single-pole, double throw switch positions possible? 1. One 2. Two 3. Three 4. Four 3-28. Control of a circuit requiring a temporary actuation signal is provided by which of the following switches?
1. Momentary 2. Locked-in 3. Locked-out 4. Rotary 3-29. To guard against the accidental actuation of a circuit, which of the following types of switches are used? 1. Momentary 2. Locked-in 3. Locked-out 4. Rotary 3-30. To guard against the accidental turning off of a circuit, which of the following types of switches are used? 1. Momentary 2. Locked-in 3. Locked-out 4. Rotary 3-31. What is the common name for a accurate snap-acting switch? 1. Maxiswitch 2. Multiswitch 3. Miniswitch 4. Microswitch 3-32. Designation of switch current rating is based on which of the following current values?
1. Maximum 2. Minimum 3. Nominal 4. Average 3-33. Designation of switch voltage rating is based on which of the following voltage values? 1. Maximum 2. Minimum 3. Nominal 4. Average 3-34. Checking a switch with the circuit power NOT applied is accomplished by using which of the following meters? 1. Wattmeter 2. Frequency meter 3. Temperature meter 4. Ohmmeter 20 3-35. Checking a switch with the power applied is accomplished by using which of the following meters? 1. Megger 2. Ohmmeter 3. Wattmeter 4. Voltmeter Figure 3-C.—Switch replacement problem.
In Answering Questions 3-36
Through 3-45, Refer To Figure 3-C.
3-36. What switch is the best substitute? 1. C 2. F 3. G 4. H 3-37. What switch is the second best substitute? 1. C 2. F 3. G 4. H 3-38. Which of the following switches is unacceptable because of the number of poles? 1. A 2. D 3. F 4. G 3-39. Which of the following switches is unacceptable because of the number of throws? 1. A 2. B 3. D 4. E 3-40. Which of the following switches is unacceptable because of the number of breaks? 1. A 2. C 3. E 4. G 3-41. Which of the following switches is unacceptable because of the number of positions?
1. C 2. D 3. E 4. F 21 3-42. Which of the following switches is unacceptable because of the momentary position? 1. C 2. F 3. G 4. H 3-43. Which of the following switches has the wrong locked position? 1. B 2. D 3. F 4. G 3-44. Which of the following switches has an unacceptable voltage rating? 1. B 2. D 3. E 4. F 3-45. Which of the following switches has an unacceptable current rating? 1. B 2. C 3. D 4. F 3-46. When you perform preventive maintenance on a switch, which of the following items should be checked? 1. The terminals for corrosion 2. The physical condition of the switch 3. The switch operation for smooth and correct operation 4. All of the above 3-47. A solenoid is based upon which of the following principles?
1. A bimetallic strip bends when it is heated 2. A thermocouple produces a current when heated 3. A coil attracts a soft iron core when current flows in the coil 4. A soft iron core moving in a magnetic field creates a current 3-48. A solenoid is commonly used in which of the following devices? 1. A fuel quantity indicating system 2. A shipboard lighting system 3. A sound-powered telephone system 4. A starter for a motor vehicle 3-49. If a solenoid is not operating properly, which of the following items need NOT be checked?
1. Coil 2. Armature 3. Plunger 4. Energizing voltage _______________________________________
In Answering Questions 3-50
Through 3-54, Match The Device(S)
Listed In Column B To The
Statements In Column A. The
Devices In Column B May Be Used
More Than Once.
A. Statements
B. Devices
3-50. An electromagnetic device 1. A switch only 3-51. A device with a movable plunger 2. A solenoid only 3-52. A device with a fixed core 3. A relay only 3-53. A device classified as power or control 4. A relay and a solenoid 3-54. A device containing an armature _______________________________________ 22 3-55. If a relay is hermetically sealed with an opaque cover, which of the following methods should be used to determine whether the relay is operating? 1. Shake the relay and listen for loose parts 2. Place your finger on the cover and feel the relay contact movement 3. Remove the cover and visually observe the relay contacts when the relay is activated 4. Activate the relay and observe whether a metal object is attracted by the magnetic field 3-56. If a relay is NOT operating properly, which of the following items need NOT be checked?
1. The armature resistance 2. The terminal leads 3. The contact surfaces 4. The contact spacing 3-57. What should be used to clean the contacts of a relay? 1. Sandpaper 2. Emery cloth 3. A jeweler's file 4. A burnishing tool 3-58. What should be used to adjust contact clearances on a relay? 1. A point bender 2. A burnishing tool 3. A pair of pliers 4. A pair of hemostats