Hottest electrical safety exercises

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Electrical safety exercises

1. Multiple choice questions

1. When there is current flowing underground at the grounding point, the current will produce a voltage drop in the soil around the grounding point. When a person is around the grounding point, the voltage between the two pins is called (a)

a: step voltage B: step potential C: critical voltage D: fault voltage

2. The power frequency current of (d) can make the light and rigid plastic pipe suffer a fatal electric shock

a: Several amperes B: Several milliamperes C: hundreds of milliamperes D: tens of milliamperes

3. When the equipment contacts the shell for leakage, the electric shock caused by human contact with the metal shell of the equipment is called (b)

a: direct contact shock B: indirect contact shock C: electrostatic shock D: non-contact shock

4. From the perspective of preventing electric shock, insulation, screen protection and spacing are the safety measures to prevent (d)

a: electromagnetic field injury B: indirect contact shock C: electrostatic shock D: direct contact shock

5. Connect the uncharged metal part of the electrical equipment with the electrical protection zero line under normal conditions, which is called (b)

a: protective grounding B: protective neutral connection C: working grounding D: working neutral connection

6. Protective neutral connection belongs to (c) system

a:it b:tt c:tn D: three-phase three wire system

7. The voltage of the portable lamp shall not exceed (a) v. in particularly humid places or on the ground with good conductivity, if the working place is narrow (such as in boilers, metal containers), and it is inconvenient to move, the voltage of the portable lamp shall not exceed (a) v

A:36; 12 B:50; 42 C:110; 36 D:50; 36

8. In the system of implementing protective zero connection, the working zero line is the neutral line, which is usually represented by (); The protective zero line is the protective conductor, which is usually represented by (). If a line is both a working zero line and a protective zero line, it is represented by ()


answer: c

9. Leakage protection devices are mainly used for ()

a: prevent personal electric shock accident B: prevent interruption of power supply C: reduce line loss D: prevent electric leakage fire accident

answer: A, d

10. Installing lightning rod, lightning wire, lightning protection and lightning strip are the main measures for protection ()

a: Lightning intrusion wave B: direct lightning strike C: counterattack D: secondary discharge

answer: b

11, () are the main measures for lightning intrusion wave of various power transformation and distribution devices

a: adopt (valve type) lightning arrester B: adopt lightning rod C: adopt lightning strip D: adopt lightning protection

answer: a

12. In general, human body resistance can be considered as ()

a:50~100 Ω b:800~1000 Ω c:100~500k Ω d:1~5m Ω

answer: b

13, () electrical equipment is an electrical equipment that can withstand the explosion of internal explosive mixture data without damage, and does not cause internal explosion and external explosive mixture explosion through any joint surface or structural hole of the shell

a: increased safety type B: intrinsically safe type C: flameproof type D: oil filled type

answer: c

14. The leakage protector with rated leakage action current of () belongs to high sensitivity type

a:30ma~1a b:3 the automotive industry will not only usher in a large period of driverless driving 0ma and below c:1a above d:1a below

answer: b

15. When electrical equipment is not convenient for insulation or insulation is not enough to ensure safety, screen protection measures should be taken. The power transformation and distribution equipment shall be equipped with perfect screen protection devices, and the height of the barrier used shall not be less than ()

a:1.4m b:1.7m c:2.0m d:2.4m answer: b

16. In order to ensure the formation of fault current circuit under fault conditions, so as to provide automatic disconnection conditions, the protective conductor is () in use

a: interrupt allowed B: interrupt not allowed C: switch on allowed D: automatic cut-off answer: b

17. Among the following power supplies, those that can be used as safety power supplies are ()

a: autotransformer B: voltage divider C: Battery D: safety isolation transformer answer: C, d

18, symbol "return" is the auxiliary mark of ()

a: basic insulation B: double insulation C: functional insulation D: shielding answer: b

19. Overhead lines should not cross ()

a: buildings with burning materials as roofs B: roads C: navigable rivers D: cableway answer: a

20. Among the following insulation safety tools, those belonging to auxiliary safety tools are ()

a: insulating rod B: insulating baffle C: insulating shoe D: insulating clamp answer: c

21. Adopting safe extra low voltage is () measure

a: only direct contact electric shock protection B: only indirect contact electric shock protection

c: used to prevent explosion and fire hazards D: both direct contact electric shock and indirect contact electric shock protection answer: d

22. Connect PE mains, grounding mains, water mains, gas mains, heating and air conditioning risers at the incoming line of the building power line, and it is best to connect the metal components of the building and other metal pipes. This measure is called ()

a: overload protection B: main equipotential bonding C: non-conductive environment D: auxiliary equipotential bonding answer: b

23. When the level of gas explosion hazardous areas belongs to zone 0 or zone 1, and the minimum ignition energy of combustibles is below (), workers should wear work without electrostatic ignition risk

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