1. For lighting and electric heating load, the safe current carrying capacity of the conductor (A) ≥ the sum of the rated currents of all electrical appliances. ( √ )
2. For lighting and electric heating load, the safe current carrying capacity of the conductor (A) ≥ the sum of the rated voltages of all electrical appliances. ( × )
3. For the power load, when using a motor, the wire safe current carrying capacity (A) ≥ the rated current of the motor. ( √ )
4. For the power load, when using a motor, the wire safe current carrying capacity (A) ≥ the rated voltage of the motor. ( × )
5, lighting circuit, wire safe current capacity ≥ melt rated current. ( √ )
6, lighting line, wire safe current capacity ≥ melt rated voltage. ( × )
7. The current carrying capacity of the three-phase four-wire neutral line should be 50% or more of the phase current carrying capacity. ( √ )
8. The current carrying capacity of the three-phase four-wire neutral line should be 30% or more of the phase current carrying capacity. ( × )
9. The loading surface of the N-line and PE lines of the two-phase three-wire or single-phase line should be the same as the phase line. ( √ )
10. The loading surface of the N-line and PE lines of the two-phase three-wire or single-phase line should be different from the phase line. ( × )
11. For the distribution line, the voltage loss or voltage drop to be generated when the load current passes through the line should also be considered. The voltage loss of low-voltage distribution lines should generally not exceed 5%. ( √ )
12. For the distribution line, the voltage loss or voltage drop to be generated when the load current passes through the line should also be considered. The voltage loss of low-voltage distribution lines should generally not exceed 10%. ( × )
13. Before the power supply is completed after the laying of the low-voltage line, the insulation resistance measurement should be carried out: measure each line of the line with a 500V shake meter. ( √ )
14. Before the power supply is completed after the laying of the low-voltage line, the insulation resistance measurement should be carried out: measure each line of the line with a 250V shake meter. ( × )
15. The insulation resistance of the new line device should not be less than 0.5MΩ. ( √ )
16. The insulation resistance of the newly built line device should not be less than 0.225 MΩ. ( × )
17. The insulation resistance can be appropriately reduced for the running line, relatively zero or ground ≥0.22MΩ ( √ )
18. The insulation resistance can be appropriately reduced for the running line, and the relative phase is ≥0.38MΩ ( √ )
19. The insulation resistance can be appropriately reduced in the running line. For 36V safe low voltage line, the insulation resistance should not be less than 0.22MΩ ( √ )
20. The insulation of the wires inside the pipe must be good, and the voltage level must not be lower than 250 VAC. ( × )
21. Generally, the total cross-sectional area of ​​the inner conductor (including the insulating layer) is not more than 40% of the cross-sectional area of ​​the inner diameter of the conduit. ( √ )
22. Generally, the total cross-sectional area of ​​the inner conductor (including the insulating layer) is not more than 60% of the cross-sectional area of ​​the inner diameter of the conduit. ( × )
23. There shall be no joints in the wires of the wire laying pipe. ( √ )
24. The wire inside the wire laying pipe can have a joint. ( × )
25. The different voltage circuits of the wires in the wire laying pipe shall not be installed in the same pipe. ( √ )
26. The different voltage loops of the wires in the wire laying pipe can be installed in the same pipe. ( × )
27. When the steel pipe is used for wire laying, it is sufficient that the wire is not more than 10 in the pipe diameter. ( × )
28. When the wire is laid, the number of wires installed in one pipe shall not exceed 8. ( √ )
29, when the power line is laid in the steel pipe, a steel pipe is required to wear a wire. ( × )
30. When the power line is laid through the steel pipe, one wire is not allowed to wear a steel pipe. ( √ )
31. When the pipe is a steel pipe (iron pipe), the pipe must be reliably grounded. ( √ )
32. When the steel pipe or PVC pipe is directly connected to the equipment, the pipe should be laid into the wiring of the equipment. ( √ )
33. When the steel pipe or PVC pipe is directly connected to the equipment, the pipe does not have to be laid into the wiring of the equipment. ( × )
34. When the pipe is a steel pipe (iron pipe), a plastic protective cover must be added at both ends of the pipe outlet. ( √ )
35. When the pipe is a steel pipe (iron pipe), it is not necessary to add a plastic protective cover at both ends of the pipe outlet. ( × )
36. When connecting with PVC pipe, the tube and the joint (box) and other devices should be connected by inserting method, and the joint surface of the joint should be coated with special glue. ( √ )
37. When connecting with PVC pipe, the tube and the joint (box) and other devices should be connected by the banding method, and the bonding surface of the joint should be coated with special glue. ( × )
38. When the wire is laid (semi-hard pipe), the length of the pipe is more than 30 meters, and a junction box should be installed in the middle. ( √ )
39. When the wire is laid (semi-hard pipe), the length of the pipe is more than 20 meters, and a junction box should be installed in the middle. ( × )
40. When the wire is laid on the wire pipe (semi-hard pipe), there are two bending pipe lengths not exceeding 15 meters. ( √ )
41. When the wire is laid on the wire pipe (semi-hard pipe), there is a bending pipe length not exceeding 20 meters. ( √ )
42. When the wire is laid on the wire pipe (semi-hard pipe), there are three bending pipe lengths not exceeding 8 meters. ( √ )
43. The low-voltage automatic air switch can only serve as a short-circuit protection. ( × )
44, leakage switch can only play a role in leakage protection. ( × )
45, the fuse can play the role of overload, short circuit, undervoltage protection. ( × )
46. ​​Temporary use of electricity for construction, its length should generally not exceed 100 meters. ( √ )
47. Temporary use of electricity for construction, its length should generally not exceed 300 meters. ( × )
48. Temporary use of electricity for construction shall be no less than 2.7 meters from the ground. ( √ )
49. Temporary use of electricity for construction shall not be less than 1.7 meters from the ground. ( × )
50. Temporary use of electricity for construction shall be carried out by means of protective zeroing (or protective earthing) or other safety measures. ( √ )
51. The length of the temporary overhead line for construction shall not exceed 500 meters. ( √ )
52. The length of the temporary overhead line for construction shall not exceed 300 meters. ( × )
53. Temporary overhead line for construction, the height from the ground should not be less than 4-5 meters. ( √ )
54. Temporary construction lines should have a limitation on the period of use, and should not exceed three months. ( √ )
55. Temporary construction lines should have a limitation on the period of use, and should not exceed six months. ( × )
56. When the temporary lines are connected to each other, the plug and the socket are applied. It is strictly forbidden to install the plugs at both ends of the connecting line. ( √ )
57. When the temporary lines are connected to each other, the plug and the socket are applied, and the plugs can be plugged at both ends. ( × )
58. It is strictly forbidden to use the earth as a neutral line for temporary power lines, that is, it is strictly forbidden to have three lines, one place, two lines, one place and one place. ( √ )
59. When connecting the device: connect the device first, followed by the power supply. When disassembling the device: first remove the power supply, then remove the device. ( √ )
60. When connecting the device: first connect the power supply, then connect the device. When disassembling the device: first remove the power supply, then remove the device. ( × )
61. When connecting the device: connect the device first, followed by the power supply. When disassembling the device: first remove the device, then remove the power supply. ( × )
62. When connecting the line: first connect the zero line, then connect the fire line. When removing the line: first remove the fire line, then remove the zero line. ( √ )
63. When connecting the line: first connect the fire line, then connect the zero line. When removing the line: first remove the fire line, then remove the zero line. ( × )
64. When connecting the line: first connect the zero line, then connect the fire line. When removing the line: first remove the zero line, then remove the line. ( × )
65. When installing the knife switch, the power incoming line should be pressed on the inlet of the static contact end, and the electrical equipment should be connected to the outlet of the lower fuse. ( √ )
66. When installing the knife switch, the power incoming line should be placed on the inlet of the fuse below, and the electrical equipment should be connected to the outlet of the static contact. ( × )
67. When the knife switch is turned off, the handle should be down. When the switch is on, the handle should be up. ( √ )
68. When the knife switch is turned off, the handle should be up. When the switch is turned on, the handle should be down. ( × )
69. The three-phase unbalanced current of the motor should not exceed 10% of the rated current. ( √ )
70. The three-phase unbalanced current of the motor should not exceed 20% of the rated current. ( × )
71. The insulation resistance between the winding and the winding of the motor and between the winding and the casing, the resistance is not less than 0.5 megohm. ( √ )
72. The insulation resistance between the winding and the winding of the motor and between the winding and the casing, the resistance is not less than 0.38 megohm. ( × )
73. If the weight of the indoor chandelier exceeds 0.5Kg, it must be supported by metal chain or other methods. ( √ )
74. If the weight of the indoor chandelier exceeds 0.25Kg, it must be supported by metal chain or other methods. ( × )
75. For indoor chandeliers with a weight of more than 3Kg, the hook should be able to withstand 10 times the weight of the luminaire. ( √ )
76. The indoor chandelier should have a pre-embedded hook with a weight of more than 1Kg. The hook should be able to withstand 10 times the weight of the luminaire. ( × )
77. The light switch must be connected in series on the phase line. The incoming line of the screw base (ie the phase line) should be connected to the center contact of the lamp head, and the neutral line should be connected to the threaded port. ( √ )
78. The light switch must be connected in series on the phase line. The incoming line of the screw base (ie the phase line) should be connected to the center contact of the lamp head, and the phase line should be connected to the threaded port. ( × )
79. The light switch must be connected in series on the zero line. The incoming line of the screw base (ie the phase line) should be connected to the center contact of the lamp head, and the neutral line should be connected to the threaded port. ( × )
80, wall switch installation should be 1.3 meters from the ground, the socket should be 0.3 meters. ( √ )
81. The wall switch should be installed at a distance of 1.5 meters from the ground and the socket should be 0.3 meters. ( × )
82. The wall socket hole is left zero right fire, and the upper hole is protection line. If the two holes are installed vertically, the lower hole is a zero line and the upper hole is a phase line. ( √ )
83. The wall socket hole is left zero right fire, and the upper hole is protection line. If the two holes are installed vertically, the lower hole is the phase line and the upper hole is the zero line. ( × )
84. The insulation resistance of household electrical appliances stipulates that household appliances should not be less than 2 MΩ. ( √ )
85. The insulation resistance of household electrical appliances shall be stipulated that the general mobile electrical equipment used for production shall not be less than 2 MΩ. ( √ )
86. The insulation resistance of household appliances is stipulated that hand-held household appliances should not be less than 7MΩ. ( √ )
87. Insulation resistance of household electrical appliances, hand-held power tools, class I should not be less than 2 MΩ, class II should not be less than 7 MΩ, class III should not be less than 1 MΩ. ( √ )
88. When moving the daily electrical appliance, the power plug must be disconnected. ( √ )
89. When moving the daily electrical appliance, it is not necessary to unplug the power plug. ( × )
90, current action type leakage protector, rated leakage current, 30mA and below is high sensitivity, fast action type should not be greater than 0.2S.
( √ )
91. The leakage switch can only protect against leakage. ( × )
92. When the substance is burned, the oxygen content in the air will be extinguished when it is less than 16%. ( √ )
93. For the leakage protector in operation, it should be checked at least once a month and the inspection record should be made. ( √ )
94. When the wire is laid on the wire pipe (iron pipe), the length of the pipe is more than 40 meters, and a junction box should be installed in the middle. ( √ )
95, low-voltage lighting on the machine, the voltage should not exceed 36V ( √ )
96. Leakage protectors for low-voltage power grids are mainly based on the consideration of ensuring the safety of personal electric shock. ( √ )
97. Leakage protectors for low-voltage power grids are mainly based on the consideration of ensuring the safety of equipment leakage. ( × )
98. The rated leakage current of the leakage protector is selected, and the special circuit for the residential building outlet is 30mA. ( √ )
99. The rated leakage current of the leakage protector is selected. The electrical equipment used in the construction site and the hand-held or mobile electrical equipment are 15-30mA. ( √ )
100. The rated leakage current value of the leakage protector is selected. The power equipment in the environment with bad environment or humidity is 6-10 mA. ( √ )
101. The rated leakage current of the leakage protector is selected. The various electrical facilities established along the street and the medical electrical equipment directly in contact with the human body are 6 mA. ( √ )
102. The rated leakage current of the leakage protector is selected to prevent the electrical fire from being 300mA. ( √ )
103. For the leakage protector in operation, it should be checked at least once a month and the inspection record should be made. ( √ )
104. Power failure maintenance work, for 10KV and below live equipment and lines, when the distance between the human body and the charged body is less than 0.35m, all power failures should be checked.
( √ )
105. Power failure maintenance work, if the distance between the human body and the charged body is greater than 0.35m, but less than 0.7m, temporary curtains should be set, otherwise all power outages should be taken. ( √ )
106. Overhaul equipment or lines. The important sign of whether the power outage is thorough is that there must be at least one obvious disconnection point in all aspects of the line, and the equipment and lines storing residual charge must be completely discharged. ( √ )
107. When inspecting electricity, it should be carried out phase by step. When checking the circuit breaker or the isolating switch, the electricity should be checked on both sides, and the detection of the neutral line and the protection line should not be ignored. ( √ )
108. When using high-voltage electroscopes, you must wear insulated gloves, electrician boots, and guardianship. ( √ )
109. When using a high-voltage electroscope, do not wear insulated gloves or electrician boots. ( × )
110. Wear insulated gloves when installing the portable grounding wire. When installing, it should be connected to the grounding terminal and then to the equipment terminal. ( √ )
111. When installing the portable grounding wire, when connecting the conductor end of the equipment; first connect one phase close to the human body, then connect other phases, and when disassembled, the order is reversed. ( √ )
112. When installing the portable grounding wire, when connecting the conductor end of the equipment; first connect one phase away from the human body, then connect the other phase, and when it is removed, the order is reversed. ( × )
113. In some power outages and repairs, if there is a possibility of contact with adjacent conductors or lines, temporary barriers and shields shall be installed when the safety distance is insufficient. ( √ )
114. In some power outages and repairs, it is possible to contact the adjacent live conductors or lines. When the safety distance is insufficient, it is not necessary to install temporary barriers and shields. ( × )
115, the role of hanging signs is to remind people to pay attention. On the handle of the knives, the sign "No closing, some people working" or "No closing, some people working on the line" should be hung. ( √ )
116, the role of hanging signs is to remind people to pay attention. At the work place, signs such as “No closure, some work†or “No closure, no work on the line†should be hanged. ( × )
117. The uninterrupted power supply and live working of the low-voltage system must obtain the consent of the relevant management departments of the factory and strictly abide by the working system. ( √ )
118. The low-voltage system does not have power-off work and live work, and does not have to obtain the consent of the relevant management department of the factory, and strictly abide by the work system. ( × )
119. Without overhaul and maintenance, the maintenance personnel shall be served by a licensed electrician who has passed the safety technical training and passed the examination and can master the non-stop power maintenance technology. ( √ )
120, no power maintenance, must use qualified and checked tools that are safe and reliable, with insulated handles. It is strictly forbidden to use tools with metal objects such as boring tools and metal rulers. ( √ )
121. No over-current maintenance, you must use qualified and inspected tools that are safe and reliable with insulated handles. A tool with a metal object such as a file or a metal ruler can be used. ( × )
122, no power maintenance, work, must ensure that there is sufficient safety distance, the live part can only be on the side of the staff. ( √ )
123, no power maintenance, work, must ensure that there is sufficient safety distance, the live part can be on the two sides of the staff. ( × )
124. Workers must wear long-sleeved tops and trousers, and fasten cuffs, gloves, safety helmets, insulated shoes, and work on dry insulating mats.
( √ )
125. Live working on the low-voltage line, the operator shall not traverse the wire before the insulation or isolation measures are adopted. ( √ )
126. Working on a low voltage line, the operator can traverse the conductor before the insulation or isolation measures are taken. ( × )
127. When working on a low-voltage line with two people working on the same pole, it is strictly forbidden to have two people working on different phases at the same time. ( √ )
128. When working on a low-voltage line, when two people work on the same pole, they can work on different phases at the same time. ( × )
129. When carrying out low-voltage live working on the pole, the operator may not carry the safety rope, and the escalator that climbs may not be removed. ( × )
130. When carrying out low-voltage live working on the pole, the operator should always carry the safety rope and the escalator that climbs should not be removed. ( √ )
131. Observe whether there is any breathing: stick the ear to the mouth and nose of the electric shocker, and use the sense of hearing and denomination to judge whether the electric shocker has the gas flow generated by the breathing. ( √ )
132. Observe whether there is breathing: stick the ear to the chest of the electric shocker, and use the sense of hearing and denomination to judge whether the electric shocker has the gas flow generated by the breathing. ( × )
133. Check if the carotid artery is pulsating: the middle finger and the index finger can be combined together, the fingertip is placed in the larynx, and then slowly moved to the neck side. If the carotid artery is beaten, the electric shock still has a heartbeat. ( √ )
134. Check whether the carotid artery is pulsating: the middle finger and the index finger can be combined together, the fingertip is placed in the heart, and then slowly moved to the neck side. If the carotid artery is beaten, the electric shock still has a heartbeat. ( × )
135. Simply diagnose the breathing and heartbeat of the electric shocker. The inspection time should be completed within 5 seconds. ( √ )
136. Simply diagnose the breathing and heartbeat of the electric shocker. The inspection time should be completed within 5 minutes. ( × )
137. The electric shock should stop mouth-to-mouth artificial respiration immediately after the patient stops breathing. The rescuer first takes a deep breath and blows it 4 times in rapid succession, then blows it 12-16 times per minute. ( √ )
138. The electric shock should stop mouth-to-mouth resuscitation immediately after the patient stops breathing. The rescuer first takes a deep breath and blows it 4 times in rapid succession, then blows 60-80 times per minute. ( × )
139. The heartbeat of the electric shock stops beating. The chest should be immediately pressed, the frequency is 60-120 times, preferably 80 times. ( √ )
140, the heartbeat of the electric shock stops beating, should immediately press the chest outside the heart, the frequency is 12-16 times, preferably in about 16 times. ( × )
141. If the electric shock is stopped by the electric shock, the chest should be pressed at the same time as the artificial respiration. The heart was squeezed 15 times after continuous insufflation for four times. After squeezing, the air was blown twice in succession and 15 times in the heart. Also check every 5 minutes, ( √ )
142. In order to ensure the safe use of current transformers, fuses should be installed on both the primary side and the secondary side. ( × )
143. Neutral grounding is called zero line, and zero line is no current flowing. ( × )
144. In the three-phase four-wire power supply system, the switch fuse cannot be installed on the neutral line. (√)
145. In the three-phase four-wire power supply system, a switch fuse can be installed on the neutral line. ( × )
146. In the system powered by the same transformer, it is not advisable to protect the grounding and protection from zero. (√)
147, the multimeter measures the resistance, and each time after the file is changed, it must be re-zeroed. (√)
148. Once someone has an electric shock, artificial respiration should be carried out immediately to make the electric shocker out of danger. ( × )
149. Three-phase asynchronous motor positive and negative control circuit, the most reliable using contactor interlocking. ( × )
150. As long as the fuse is installed in the line, the circuit works normally regardless of its specifications. ( × )
151. When measuring the resistance with a multimeter, the pointer should be zeroed every time the ohmic file is changed. (√)
152. Whether it is measuring direct current or alternating current, the illumination of the xenon lamp of the electroscope is the same. (×)
153. The safe current carrying capacity of the wire should have different values ​​under different ambient temperatures. The higher the ambient temperature, the larger the safe current carrying capacity. (×)
154. An experienced electrician does not have to use the electroscope test to perform maintenance after a power outage. (×)
155. After using the 36V safe voltage, it will definitely ensure that there will be no more electric shock accidents. (×)
156. The larger the wattage of an incandescent light bulb used in electrical lighting, the smaller its resistance. (√)
157. In the voltage transformer in use, the secondary side is absolutely not allowed to be short-circuited. (√)
158. The secondary winding of the voltage transformer is not allowed to open, and the secondary winding of the current transformer is not allowed to be short-circuited. (×)
A DC ammeter can be used for the AC circuit. (×)
159. Whether it is measuring direct current or alternating current, the illumination of the xenon lamp of the electroscope is the same. (×)
160. The safe current carrying capacity of the wire should have different values ​​at different ambient temperatures. The higher the ambient temperature, the greater the safe current carrying capacity. (×)
161. The power phase (fire) line can be directly connected to the luminaire, and the switch can control the ground. (×)
162. Safety voltage lighting transformers use double-turn transformers, and autotransformers can also be used. (×)
163. The phase (fire) line of the screw cap should be connected to the tongue on the center of the lamp socket, and the neutral wire is connected to the threaded port. (√)
164. When the asynchronous motor adopts Y-Δ step-down starting, the stator windings are first connected by Δ, and then changed to Y-connected operation. (×)
165. If the low-voltage temporary lighting is installed very reliably, it can also adopt the “one-line-one-ground system†power supply mode. ( × )
166. If electrical equipment is not equipped with safety measures, it should still be considered as having electricity. ( √ )
167. If the clamped ammeter is zero when the total current of the three phases is measured, it means that there is a problem with the meter. ( × )
168. If high-voltage equipment is used to extinguish the fire with a dry powder fire extinguisher, do not wear insulated gloves and wear insulated boots. ( × )
1. The insulation of the wire through pipe must be good, and its voltage level must not be lower than AC (D) volt.
A36 B220 C380 D500
2, the wire through the pipe generally requires the total cross-sectional area of ​​the wire (including the insulation layer) is not greater than the cross-sectional area of ​​the inner diameter of the pipe (C).
A 20% B 30% C 40% D50%
3. The wire installed in a pipe shall not exceed (A) the wire.
A8 B10 C12 D15
4. When connecting with PVC pipe, the nozzle should be smooth and smooth, and the pipe and pipe, pipe and joint (box) and other devices should be connected (B), and the bonding surface of the joint should be coated with special glue.
A dressing B insertion method
5, the wire through the pipe must be worn in the piping project (B).
After the start of work, after B is completed, C is completed before the start of construction.
6. When laying the line pipe, when the length of the semi-rigid pipe exceeds the following, a junction box (B) should be installed in the middle.
A20 B30 C40 D50
7. When laying the line pipe, when the length of the iron pipe exceeds the following, a junction box (C) shall be installed in the middle.
A20 B30 C40 D50
8. When laying the line pipe, there is a bending line pipe length not exceeding (D) meters, and a junction box should be installed in the middle.
A5 B8 C10 D20
9. When laying the line pipe, there are two bending line tubes not exceeding (C) meters, and a dividing box should be installed in the middle.
A5 B8 C15 D20
10. When laying the line pipe, there are three bending line tubes not exceeding (B) meters, and a dividing box should be installed in the middle.
A5 B8 C15 D20
11. Temporary overhead lines must not exceed (D) meters
A100 B200 C300 D500
12. Temporary lines should have a limitation on the period of use and should generally not exceed (C) months.
A1 B2 C3 D4
13. The current carrying capacity of the three-phase four-wire neutral line should be (D) and above the phase current carrying capacity.
A10% B20% C30% D50%
14. How to operate the high voltage disconnector correctly: ( A )
A. To cut off the power supply, first pull the short circuiter and then pull off the isolating switch.
B. When closing the power supply, first close the short circuiter and then close the isolation switch.
C. When disconnecting the power supply, first pull the isolation switch, then pull the short circuit.
D. When the power is turned off, it has nothing to do with the switch.
15. When an electrician works on a live low-voltage line, the correct approach is: (A)
A. Disconnect the wire before breaking the phase line and then breaking the zero line.
B. When connecting the wires, the phase wires should be connected first, followed by the neutral wires.
C. No matter which line is connected first or first, it does not affect the requirements of the work.
16. When the electrocardiographer's heartbeat stops breathing, the rescue should be performed using (C).
A, artificial respiration
B, chest compressions
C, artificial respiration and chest compressions
17. The color of the bus phase sequence defines the L1 (U) phase, the L2 (V) phase, and the L3 (W) phase. (A)
A, yellow, green, red
B, green, red, yellow
C, yellow, red, green
D, red, yellow, green
18. The secondary coil of the voltage transformer has a little grounding. This grounding should be called (C).
A. Repeat grounding B, working ground C, protective grounding
19. The rated current of the secondary side of the current transformer is generally BA.
A, 2; B, 5; C, 10; D, 15,
20. The rated voltage of the secondary side of the voltage transformer is generally CV.
A, 50; B, 80; C, 100; D, 150
21, the main role of the fuse is __B___ protection.
A, undervoltage; B, short circuit; C, 10 open circuit; D, open circuit
22. The grounding resistance of the protective earthing should be R≤__C___ ohm.
A, 2; B, 3; C, 4; D, 5
23, the depth of the grounding body into the ground is not less than __B__ meters,
A, 2; B, 2.5; C, 3; D, 3.5
24. The distance between the two grounding bodies shall not be less than __D___ meters.
A, 2; B, 2.5; C, 3; D, 5
25. The Y-â–³ step-down starting mode is adopted for the motor. When starting, the stator winding should be connected to the ____A_____ shape.
AY Bâ–³ C Y-â–³
26. Connect one or more points on the zero line to the ground again through the grounding device, called ____D_____.
(A) Working ground (B) Protective grounding (C) Protective zeroing (D) Repeated grounding
27, for 220V voltage line insulation resistance, the requirements are not less than (2)
10.036MΩ 20.22 MΩ 30.5 MΩ
28, for 380V voltage line insulation resistance, the requirements are not less than (1)
10.038MΩ 20.22 MΩ 30.5 MΩ
29, for the insulation resistance of the 36V voltage line, the requirements are not less than (2)
10.036MΩ 20.22 MΩ 30.5 MΩ
30. When the power is off and overhauled, the following signs should be hung on the operating handle of the switch or knife switch that can be sent to the work place after closing. (3)
1 "Work here!" 2 "Stop, high voltage danger!" 3 "No closing, someone working!"
31. When the three-phase asynchronous motor is started by Y-â–³ decompression, its starting current is the full-voltage starting current (A).
A, 1/3 B, 1 C, 1 / 2 D, multiple cannot be determined
32. In the following meter accuracy level grouping, it can be used as engineering measuring instrument in group (c).
a , 0.1 , 0.2 b , 0.5 , 1.0 c , 1.5 , 2.5 , 5.0
33. To measure the insulation resistance of 380V AC motor, the insulation resistance meter with rated voltage b should be selected. (b)
a, 250V b, 500V c, 1000V
34. The melt in the fuse plays a role in the circuit. (3)
1 overload protection 2 loss of voltage protection 3 short circuit protection
35, low-voltage lighting on the machine, the voltage should not exceed (2)
1110V 236V 312V
36. When testing 220V DC with a low voltage electroscope, the illumination of the bulb is (2)
1 two-pole light 2 pole light 3 light
37. When performing chest compressions, the number of movements per minute should be (2)
116 times 280 times 3 not less than 120 times
38. What are the main functions of the safety production regulations? (ABC)
A. Ensuring the legitimate rights and interests of workers and mobilizing the enthusiasm of workers
B promotes production and economic development
C promotes social stability
39. Article 42 of the Constitution stipulates: "The workers of the People's Republic of China have (A). The state develops facilities for rest and recuperation of laborers, and stipulates the working hours and vacation system for employees."
A. Rights and obligations for rest B. Powers and obligations of labor C. Powers and obligations for compensation
40. On June 29, 2002, the 28th meeting of the Standing Committee of the National People's Congress passed the "Safety Law of the People's Republic of China" (hereinafter referred to as the "Safe Production Law"), which was implemented in 2002 (C).
A May 1st, B1, 1st, C11, 1st, D12th
41. The "Safety Law" strictly stipulates that special operations personnel must undergo special safety operation training, and after obtaining the (C) operation qualification certificate, they can get on the job.
A, occupation B, grade C, special operations D, special operations personnel
42. Article 82 of the Sixth Chapter of the Security Law stipulates: "If the production and business unit has one of the following acts, it shall be ordered to make corrections within a time limit; if it fails to make corrections within the time limit, it shall be ordered to suspend production and suspend business for rectification, and may be concurrently imposed a fine of (C).
A, 5,000 yuan B, 10,000 yuan C, 20,000 yuan D, 50,000 yuan
Signal
Response time refers to the response speed of the Liquid Crystal Display to the input signal, that is, the response time of the liquid crystal from dark to bright or from bright to dark (the time for the brightness from 10%-->90% or 90%-->10%) , Usually in milliseconds (ms). To make this clear, we have to start with the human eye's perception of dynamic images. There is a phenomenon of "visual residue" in the human eye, and the high-speed motion picture will form a short-term impression in the human brain. Animations, movies, etc. to the latest games have applied the principle of visual residue, allowing a series of gradual images to be displayed in rapid succession in front of people's eyes to form dynamic images. The acceptable display speed of the picture is generally 24 frames per second, which is the origin of the movie playback speed of 24 frames per second. If the display speed is lower than this standard, people will obviously feel the picture pause and discomfort. Calculated according to this index, the display time of each picture needs to be less than 40ms. In this way, for the liquid crystal display, the response time of 40ms becomes a hurdle, and the display above 40ms will have obvious picture flicker, which makes people feel dizzy. If you want the image screen to reach the level of non-flicker, it is best to achieve a speed of 60 frames per second.
I used a very simple formula to calculate the number of frames per second under the corresponding response time as follows:
Response time 30ms=1/0.030=approximately 33 frames per second
Response time 25ms=1/0.025=approximately 40 frames per second
Response time 16ms=1/0.016=approximately 63 frames per second
Response time 12ms=1/0.012=approximately 83 frames of pictures displayed per second
Response time 8ms=1/0.008=approximately 125 frames per second
Response time 4ms=1/0.004=approximately 250 frames per second
Response time 3ms=1/0.003=approximately display 333 frames per second
Response time 2ms=1/0.002=approximately 500 frames per second
Response time 1ms=1/0.001=approximately 1000 frames per second
Tip: Through the above content, we understand the relationship between response time and the number of frames. From this, the response time is as short as possible. At that time, when the LCD market first started, the lowest acceptable range of response time was 35ms, mainly products represented by EIZO. Later, BenQ's FP series came out to 25ms. From 33 to 40 frames, it was basically undetectable, and it was really quality. The change is 16ms, displaying 63 frames per second to meet the requirements of movies and general games, so 16ms is not obsolete. With the improvement of panel technology, BenQ and ViewSonic started a speed battle. ViewSonic started from 8ms to 4ms. Released to 1ms, it can be said that 1ms is the final controversy of LCD speed. For game enthusiasts, 1ms faster means that CS's marksmanship will be more accurate, at least psychologically, such customers should recommend the VX series of monitors. But everyone should pay attention to the grayscale response when selling. The text difference in full-color response may sometimes mean the same thing as gray-scale 8ms and full-color 5ms. It is the same as when we sold CRTs before, we said that the dot pitch is .28, LG just I have to say that he is .21, but the horizontal dot pitch is ignored. In fact, the two are talking about the same thing. LG has come up with a sharpness of 1600:1. This is also a conceptual hype. Everyone uses the basic screen. There are only a few companies on the list, and how can only the LG family achieve 1600:1, and everyone stays at the level of 450:1? When it comes to consumers, the meaning of sharpness and contrast is obvious, just like AMD's PR value, which has no real meaning.
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