National electrician operation certificate test questions - Solutions - Huaqiang Electronic Network
First, single-choice questions
1. Repeated grounding on the overhead line of the overhead line has __C_________.
A. Prevent electric shock B. Prevent leakage current C. Improve the lightning protection performance of overhead lines D. None of the above
2. Three-phase symmetrical AC load, connected by star to the power supply with phase voltage of 220 volts. It is known that the current in the load is 10A and the power factor is 0.8, and the total power of the circuit is __A_ watt.
A. 5280 B. 3048 C. 1760
3. The value of the AC current read on the clamp ammeter is the current _D_____.
A. Maximum value B. Instantaneous value C. Average value D. Effective value
4, the coloring of the busbar has a unified regulation, wherein the color of the V-phase line is defined as ___B___.
A. Yellow B. Green C. Red D. Black
5, power equipment (power) isolation switch should use ___C____.
A. Low voltage circuit breaker B. AC contactor C. Knife switch D. Oil switch
6. The back channel of the low-voltage power distribution device should not be low-voltage __B___M.
A. 0.8 B. 1.0 C. 1.5 D. 2
7. When a fire occurs in electrical equipment, __B___ should be used first.
A. Use a non-conductive fire extinguisher to save B. Disconnect the oil switch or automatic switch D. Disconnect the disconnector
8. For a single-phase power supply line, the calculation and voltage loss test requires that the wire cross-section should not be less than 3mm2, so the wire of ___B____mm2 should be selected.
A. 3 B. 4 C. 5 D. 6
9. When the high-voltage equipment is not powered, the __A____ electrical staff separately removes or passes over the obstruction to work.
A. Not allowed B. Permitted C. No specific regulations D. None of the above
10. The thermal relay is used as a ___B_____ protection device.
A. Short circuit B. Motor overload C. Overload D. Motor phase loss
11. The "220V, 40W" lamp L1 is connected to the 220V circuit. The "36V, 40W" lamp is connected to the 36V circuit, then ___C______.
A. L2 is brighter B. L1 is brighter C. It is as bright as D. Unable to determine
12. __A____ when installing the lamp head.
A. The switch must be installed on the live wire. B. The lamp thread must be installed on the fire line.
C. Do not make explicit requirements D. The spring piece in the center of the lamp socket must be installed on the zero line.
13. The operating time and leakage current value of the inverse time action type leakage protector ___B______.
A. proportional to B. inversely proportional to C. irrelevant D. proportional
14. When the low-voltage equipment is out of power and maintenance, the power supply of all aspects of the maintenance equipment shall be disconnected immediately, ____C___.
A. Work B. Hang the sign C. Remove the fuse D. Install the ground wire
15. The meter for measuring the insulation resistance is ___B______.
A. Grounding shaker B. Shaking table C. Multimeter D. Clamping ammeter
16. The allowable current carrying capacity of the conductor shall be the maximum operating current of the __A_____ conductor.
A. Greater than B. Less than C. Equal to D. Depending on the situation
17. In the three-phase five-wire system, when leakage protection is used, __A_____ should pass through the zero-sequence current transformer.
A. Working zero line B. Protecting the zero line C. Working the zero line and protecting the zero line D. None of the above
18. When measuring the insulation resistance of low-voltage cables and secondary cables, use the __A_____ shaker.
A. 500V B. 1000V C. 2500V D. 380V
20. The color of the busbar has a uniform regulation, and the color of the W phaseline is defined as _C_____.
A. Yellow B. Green C. Red D. Black
21. In the insulation monitoring of the ungrounded voltage grid, when the three voltmeter readings are phase voltage, it means the grid _C____.
A. One phase grounding occurs B. A phase insulation deteriorates C. Ground insulation is normal D. Unable to judge
22. It is strictly forbidden to pass the working current on ___B___, and it is strictly prohibited to disconnect the line.
A. N line B. PE line C. Fire line D. Phase line
23. When the load current reaches the rated current of the fuse melt, the melt will be __D____.
A. Immediately blow B. Blow after a long delay C. Fuse after a short delay D. Will not blow
24, three-phase symmetrical load is connected to the three-phase power supply with line voltage of 380V by delta connection. The known load current is 10A, then the current in the live line is __A_____
A. 17.32 B. 10 C. 30 D. 15
25. Use three voltmeters to monitor the insulation of the neutral grounded ungrounded grid. When single phase grounding occurs, the ground phase voltmeter reads __A_____.
A. Drastically reduced B. Significantly increased C. No change D. Significantly elevated
26, install a single-phase three-hole socket, the zero-line hole is in the ___C____ side.
A. Upper B. Lower C. Left D. Right
27. The capacitor bank is not allowed to install _C_____.
A. Switch B. Fuse C. Automatic compound brake device D. None of the above
28. The coloring of the busbar has a uniform regulation, in which the color of the ungrounded neutral is defined as __D____.
A. White B. Green C. Blue D. Purple
29. In places with explosive dangers, the wiring method should use _B____ wiring.
A. Wire tube B. Steel tube C. Plastic tube D. Snake tube
30. The distance between high-heat lamps and flammable materials such as iodine-tungsten lamps should not be less than _A_____mm.
A. 1000 B. 800 C. 300 D. 500
31. Low-voltage distributors arranged in double rows, the width of the channel before the screen is not low __D___m.
A. 0.8 B. 1.0 C. 1.5 D. 2
32. In a purely inductive sinusoidal AC circuit, the following statement is correct __B_____.
A. Current lead voltage 90° B. Current hysteresis voltage 90° C. IL=ULm/XL D. Power consumed is active power
33. The rated current of the melt on the high voltage side of the transformer with a capacity below 100KV is selected according to the ___B___ times of the rated current of the transformer.
A. 1.5-2 B. 2-3 C. 1 D. 4
34. The secondary side circuit of the current transformer adopts copper core insulated wire, and its cross section should not be less than ____B___mm2.
A. 1.5 B. 2.5 C. 1 D. 4
35. When measuring the line current with a clamp-type ammeter, in order to make the result accurate, the wire is wound around the jaws for 3 turns and the reading is 15A, then the current of the load is ___A___.
A. 5A B. 15A C. 3A D. 45A
36. The order of removing the temporary ground wire is __A____.
A. First remove the conductor end, then remove the ground end B. Line the ground end, then remove the conductor end
C. In no case, D. None of the above.
37. It is known that the potential at point B is 5 volts, and the voltage between two points of AB is UAB=+10V, and the potential at point A is __B____ volt.
A. 5 B. 15 C. +10 D. -15
38. The fuse of the main circuit device of the three-phase asynchronous motor has the function of __B____.
A. Overload protection B. Short circuit protection C. Overload and short circuit double protection D. Loss of voltage protection
39. At the construction site, the signboard of ___C___ should be hung on the fence adjacent to the live equipment.
A. Work here B. Prohibit the closing, some people work C. Stop, high pressure danger D. Do not close
40. When the load of the line or equipment exceeds the allowable range, the protection mode for cutting off the power supply after delay is ___B___ protection.
A. Loss of pressure B. Overload C. Phase loss D. Short circuit
42. Training for special operation electricians, examination and certification are responsible for __D____.
A. Local human resources and labor security department B. Local union
C. Local power supply department D. Local safety production supervision and management department
43. The grounding wire for assembly and disassembly should be carried out by _B____ people.
A. 1 B. 2 C. 3 D. 4
44. On the distribution line with short-circuit protection, the long-term allowable load current of the conductor shall not be less than ___A___ times the rated current of the melt of the line. A. 0.4 B. 0.8 C. 1.25 D. 2.5
45. According to the regulations, the voltage loss allowed by the 220V line is _B_____.
A. 22V B. 11V C. 20V D. 250V
46. ​​In the enterprise, the method of calculating electric energy according to the reading of the meter is __D____.
A. Last reading - this reading B. This reading - last reading
C. This reading D. (this reading - last reading) × magnification
47. When leakage protection is used in the three-phase four-wire system, __C___ should pass through the zero-sequence current transformer.
A. Neutral B. Phase C. Phase and Neutral D. None of the above
48. The lamps marked "220V, 40W" and "220V, 60W" are each connected, and connected to a power supply with a voltage of 220V in series, then __A__.
A. The 40W lamp is brighter than the 60W lamp. B. The 60W lamp is brighter than the 40W lamp. C. The two lamps are as bright as D. Unable to determine
49. When using 1211 non-conducting fire extinguisher to extinguish the fire, the minimum distance between the human body and the fire extinguisher nozzle to the charged body is ____A___m for 10 kV. A. 0.4 B. 0.7 C. 1 D. 0.6
50. The instantaneous release of the low-voltage release is used as _____B____ protection on the line.
A. Overload B. Short circuit C. Loss of pressure D. Undervoltage
Second, multiple choice questions
1. Commonly used lightning arresters have __BC_____.
A. Angle protection gap B. Tube arrester C. Valve arrester D. Nonlinear resistance E. Valve resistance
2. The safety measures to ensure electrical work can be divided into ___BD_____.
A. Power outage measures B. Organizational measures C. Power inspection measures D. Technical measures E. Power transmission measures
3. The electrical staff must have _ABCD_______.
A. Conditions that do not interfere with work B. Have the necessary electrical knowledge and pass the exam C. Learn to receive electric shock first aid D. Ideological and political awareness high E. Familiar with the performance of the power supply system
4. Working on high voltage equipment must comply with __ABCD______.
#p#分页头#e#A. Fill in the work ticket or verbal and telephone order B. At least two people should work together
C. Completion of the safety organization measures to ensure the staff D. Safety technical measures to complete the explosion workers
E. Accident handling should fill in the work ticket
5, the common fault of the lighting line is _BDE______.
A. The voltage is too high B. Open circuit C. Poor contact of the connector D. Short circuit E. Leakage
6. For fire extinguishing of rotary electrical equipment, the fire extinguishing agent that can be used is __BCE_______.
A. Dry powder fire extinguishing agent B. 1211 fire extinguishing agent C. carbon dioxide D. sand soil E. carbon tetrachloride
7. The allowable limit operating temperatures for Class A and Class E insulation materials are ___BC_____°C.
A. 90 B. 105 C. 120 D. 155 E. 180
8. The following voltages belong to the safe voltage level: __CD_______.
A. 50V B. 20V C. 12V D. 36V E. 220V
9. The wiring of the capacitor is divided into __BC_____.
A. When the rated voltage of the capacitor and the power grid are the same, the capacitor should be connected to the star
B. When the rated voltage of the capacitor and the power grid are the same, the capacitor should be connected to a triangle C. When the rated voltage of the capacitor is lower than the rated voltage of the power grid, the capacitor should be connected to the star D. When the rated voltage of the capacitor is lower than When the rated voltage of the power grid is set, several capacitors or capacitor banks can be connected in series and then connected in a triangle. E. When the rated voltage of the capacitor is the rated voltage of the low-voltage power grid, the capacitor can be connected in series with the resistor and then connected into a triangle.
10. According to the grid neutral point operation mode, the grid can be divided into ____BD____.
A. Three-phase three-wire grid B. Ground grid C. Single-phase grid D. Ungrounded grid E. Three-phase four-wire grid
11. The resistance of the metal conductor is related to the following factors: __ACD_____.
A. Conductor length B. Applied voltage magnitude C. Conductor cross section D. Conductor resistivity E. Current flowing
12. The electrical line considers its main requirement from the perspective of safety as __ABC______.
A. Conductivity B. Insulation strength C. Mechanical strength D. Current size E. Cross-sectional size
13. The following conditions must occur when the capacitor is running. ___ABD_____ must be stopped immediately.
A. Enclosure expansion B. Severe oil leakage or abnormal noise C. Three-phase current is unbalanced
D. The three-phase current is seriously unbalanced. E. The voltage exceeds 1.05 times the rated value.
14. The abnormality that causes excessive heating of electrical equipment allows for ___ABCDE____.
A. Short circuit B. Overload C. Poor contact D. Poor heat dissipation E. Iron core heating
15. The following wires conform to the standard cross section and are __ABE_____.
A.35mm2 B.50mm2 C.75mm2 D.90mm2 E.120mm2
16. When the high and low voltage poles are installed on the low voltage line, they must pay attention to __ABCD_____.
A. Distance between line inspection and high voltage line B. Measures to prevent accidental contact with live high voltage line
C. Workers must not pass through low-voltage live conductors that are not insulated
D. Separation measures to prevent phase-to-phase short circuit and single-phase grounding
17. The following materials are classified as ___ABCDE_____ for insulating materials.
A. Glass B. Cloth C. Paper D. Mineral oil E. Ceramics
18. __BDE________ should be noted when measuring the current of lines and equipment using a clamp ammeter.
A. Must be powered off B. Select the appropriate range C. Can not measure the current of the bare wire
D. Do not switch the range during the measurement process. E. Do not use the clamp ammeter to measure the current of the high voltage circuit.
19. In the purely sinusoidal AC circuit, the following conclusions are correct __ABD_____.
A. Voltage is proportional to current B. Consumption of active power C. Consumption of reactive power
D. Voltage and current phase are the same E. Voltage lead current is 90°
20. The selection of the cross section of the indoor wiring conductor is mainly based on __ABE_____.
A. The safe current value of the wire B. The allowable voltage drop of the line C. The level of the voltage
D. Degree of insulation of the wire E. Mechanical strength of the wire
Third, the judgment question
1. Under the same insulation and normal allowable conditions, the grounding grid is less dangerous than the ungrounded grid in terms of single-phase electric shock.
2. The main function of repeated grounding is to reduce the risk of electric shock caused by the disconnection of the neutral line.
3. For cage-type asynchronous motors that are directly started, the rated current of the melt can be selected according to 1.3 times the rated current of the motor.
4. In the event of a personal electric shock, immediately report the power to the equipment after reporting to the superior.
5. The arrester can prevent tall buildings from being struck by lightning.
6, 220V, 60W bulbs and 220V, 40W bulbs, while working at rated voltage, the current flowing through the 40W bulb is large.
7. The function of protective grounding is to limit the grounding voltage of the leakage device to below the safe voltage.
8, electric shock is the value of current through the body, destroying the normal work of the human heart, lungs and nervous system, and even endanger people's lives.
9. The rated voltage of the low-voltage power supply of the power supply enterprise; the single-phase is 220V, and the three-phase is 380V.
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