Question bank of the latest operation certificate

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The latest electrician special industry operation certificate, question bank (100)

Original: welcome to pay attention to

the author's article direction: electrical, automotive, life, scientific and technological knowledge

1. The rated working voltage of AC contactor refers to the () voltage that can ensure the normal operation of electrical appliances under specified conditions

a, minimum B, maximum C, average

[answer] b

2. The two basic principles that should be followed in the correct selection of electrical appliances are the safety principle and () principle

a, economy B, performance C, function

[answer] a

3. The protection characteristics of the thermal relay are close to the overload characteristics of the motor, in order to give full play to the () ability of the motor

a, overload B, control C, throttling

[answer] a

4. The protection characteristics of fuses are also known as ()

a, ampere second characteristic B, arc extinguishing characteristic C, timeliness

[answer] a

5. The function of parallel power capacitor is ()

a, reduce the power factor

b, increase the power factor

c, maintain the current

[answer] b

6. In order to prevent the step voltage from causing harm to people, it is required that the minimum distance between the lightning protection grounding device and the entrance and exit of the building and the sidewalk should not be less than () meters

a, 3 B, 2.5 C, 4

[answer] a

7. The grounding resistance of anti-static shall not be greater than () ω。

a, 10 b, 40 C, 100

[answer] c

8. The re grounding of other grounding points on PE line or pen line is called () grounding

a, direct B, indirect C, repeat

[answer] c

9. The use of safety rope should ()

a, hang high and use low B, call low C, ensure safety

[answer] a

10, "no switching on, someone working" signs should be made as ()

a, white on red background B, red on white background c, green on white background

[answer] b

11. When the electrical equipment has a grounding fault, the grounding current flows to the earth through the grounding body. If a person walks around the grounding short-circuit point, the electric shock caused by the potential difference between his two feet is called () electric shock

a, single-phase B, step voltage C, induced electricity

[answer] b

12. According to the line voltage level and user object, power lines can be divided into distribution lines and () lines

a, lighting B, power C, power transmission

[answer] c

13. Among the following materials, the conductivity is the best ()

a, aluminum B, copper C, iron

[answer] b

14. When the middle joint of the conductor is hinged, twist () circles in the middle first

a, 2 B, 1 C, 3

[answer] c

15. The national standard stipulates that all motors above () kW adopt triangle connection

a, 3 B, 4 C, 7.5

[answer] b

16. Step down startup refers to the alternative opening and closing of valve port II and IV. during startup, reduce the voltage applied to the motor () winding, and then restore its voltage to the rated voltage for normal operation after startup

a, rotor B, stator C, stator and rotor

[answer] b

17. When the motor operates under the rated working state, the () applied by the stator circuit is called the rated voltage

a, line voltage B, phase voltage C, rated voltage

[answer] a

18. When using wire strippers, the cutting edge that is larger than the wire diameter () should be selected

a, slightly larger B, the same C, larger

[answer] a

19. On each single-phase circuit in the lighting system, the number of lamps and sockets should not exceed ()

a, 20b, 25C, 30

[answer] b

20. The wire connector is not tightly connected, which will cause the connector ()

a, insufficient insulation B, heating C, non-conductive

[answer] b

21, fluorescent lamp belongs to () light source

a, gas discharge B, thermal radiation C, biological discharge

[answer] a

22. When a low-voltage electrical fire occurs, the first thing to do is ()

a, quickly try to cut off the power supply

b, quickly leave the scene to report to the leader

c, quickly extinguish the fire with dry powder or carbon dioxide extinguisher

[answer] a

23. If special operators fail to receive special safety operation training and obtain corresponding qualifications as required, and work on duty, they shall be ordered to the production and business unit ()

a, make corrections within a time limit B, fine C, stop production and business for rectification

[answer] a

24. Special operation personnel must be at least () years old

a, 19b, 18C, 20

[answer] b

25. The total resistance of three resistors with equal resistance in series is () times of the total resistance in parallel

a, 6b, 9 C, 3

[answer] b

26. The magnitude of the electromagnetic force is proportional to the effective length of the conductor ()

a, inverse ratio B, proportional ratio C, constant

[answer] b

27, unipolar semiconductor device is ()

a, diode B, bipolar diode C, FET

[answer] C

28, () the instrument is composed of a fixed permanent magnet, a rotatable coil and shaft, hairspring, pointer, mechanical zero adjustment mechanism, etc

a, electromagnetic type B, magnetoelectric type C, inductive type

[answer] b

29. When measuring the insulation resistance of the motor coil to the ground, the "L" and "e" of the megger and the two terminals should be ()

a, "e" is connected to the terminal of the motor outgoing line, "L" is connected to the shell of the motor

b researchers tested the metal coated and uncoated samples of the material reinforced with carbon fiber, "L" is connected to the terminal of the motor outgoing line, "e" is connected to the shell of the motor

C, casually, there is no provision

[answer] B

30. The multimeter is essentially a () instrument with rectifier

a, electromagnetic B, magnetoelectric C, electric

[answer] B

31. Non automatic switching electrical appliances work by () direct operation

a, external force (such as manual control) B, electric C, induction

[answer] a

32. Low voltage fuses are widely used in low-voltage power supply and distribution systems and control systems, mainly for () protection, and sometimes for overload protection

a, short circuit B, quick break C, overcurrent

[answer] a

33. When the current relay is used, its suction coil is directly or through the current transformer () in the controlled circuit

a, parallel B, Series C, series or parallel

[answer] b

34. In the use of multi-stage fuse protection, the rated current of the melt in the later stage is greater than that in the previous stage, in order to prevent the fuse from fusing beyond the level ()

a, reduce the power failure range

b, difficulty in troubleshooting

c, expand the power failure range

[answer] c

35, the capacitor should be () after the pointer swings when checking with a multimeter

a, keep still B, gradually swing back C, swing back and forth

[answer] b

36. The lightning rod is a commonly used lightning arrester. During installation, the lightning rod should be equipped with an independent grounding device. If it is in a non high resistivity area, its grounding resistance should not exceed () ω。

a, 4b, 2C, 10

[answer] c

37. In order to avoid direct lightning strikes on high-voltage power transformation and distribution stations, leading to large-scale power outages, it is generally possible to use () for lightning protection

a, lightning rod B, valve arrester C, lightning

[answer] a

38. For low-voltage distribution, when the distribution capacity is below 100kW, the grounding resistance of equipment protective grounding should not exceed () ω。

a, 6b, 10C, 4

[answer] b

39, () can be used to operate high-voltage drop fuses, single pole disconnectors and install temporary grounding wires

a, insulating gloves B, insulating shoes C, insulating rod

[answer] c

40. Before climbing the pole, the foot buckle should be ()

a, human load impact test

b, human static load test

c, human load tensile test

[answer] a

41. Generally, the resistance of human body under the action of 220V power frequency voltage is () ω。




[answer] c

42. The color of protective wire (grounding or neutral wire) shall be adopted according to the standard ()

a, red B, blue C, yellow and green

[answer] c

43, low voltage circuit breaker is also known as ()

a, knife switch B, main switch C, automatic air switch

[answer] c

44, the setting current of the thermal relay is ()% of the rated current of the motor

a, 120b, 100C, 130

[answer] b

45. Star delta step-down starting is to connect the three-phase windings of the stator () during starting

a, triangle B, star C, extended triangle

[answer] b

46. Clean the dirt and dust inside the motor, and apply ()

a, wipe with gasoline and kerosene on the cloth

b, wipe with wet cloth

c, blow with compressed air or wipe with a dry cloth

[answer] c

47. Check the insulation of each winding of the motor. If the insulation resistance is measured to be zero, when it is found that there is no obvious burning phenomenon, it can be dried. At this time (), it is powered on

a, allow B, do not allow C, dry it well

[answer] B

48. Accident lighting is generally used ()

a, fluorescent lamp B, incandescent lamp C, high-pressure mercury lamp

[answer] b

49. The thread of screw cap should be connected with ()

a, phase line B, zero line C, ground line

[answer] b

50. In the circuit, the switch should be controlled ()

a, zero line B, phase line C, ground wire

[answer] b

51. Electrical fire is caused by the existence of dangerous temperature, which is mainly caused by ()

a, voltage fluctuation B, light equipment load C, excessive current

[answer] c

52, low voltage live line operation, ()

a, it is necessary to wear insulating gloves, but also someone to monitor

b, wear insulating gloves, no one to monitor

c, someone to monitor does not need to wear insulating gloves

[answer] a

53, pure capacitive components in the circuit () electric energy

a, storage B, distribution C, consumption

[answer] a

54. The cross-sectional area of the zero line of the three-phase four wire system is generally () the cross-sectional area of the phase line

a, less than B, greater than C, equal to

[answer] a

55. AC 10kV bus voltage refers to AC three-phase three wire system ()

a, line voltage B, phase voltage C, line voltage

[answer] a

56. The clamp on ammeter is made using the principle of ()

a, voltage transformer B, current transformer C, transformer

[answer] b

57. When measuring voltage, the voltmeter should be connected with the circuit under test ()

a, Series B, parallel C, positive connection

[answer] b

58. Low voltage appliances can be divided into automatic switching appliances and () appliances according to their action mode

a, non automatic switching B, non electric C, non mechanical

[answer] a

59. The electrical life of AC contactor is about () times of the mechanical life

a, 1b, 10C, 1/20

[answer] c

60. When the iron clad switch is used to control the start and stop of the motor, the rated current is required to be greater than or equal to () times the rated current of the motor

a, one B, two C, three

[answer] B

61. The composition of the travel switch includes ()

a, protection part B, coil part C, reaction system

[answer] c

62, capacitor bank prohibited ()

a, live closing B, charged closing C, power failure closing

[answer] b

63. One of the conditions for explosion and fire caused by static electricity is ()

a. electrostatic energy should be large enough

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