Comprehensive exercises for the hottest certified

Comprehensive exercises for certified safety engineer examination

1. Multiple choice question when there is current flowing underground at the grounding point, the current will produce a voltage drop in the soil around the grounding point if PPC enters people's daily life. 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: power frequency current of fault voltage (d) can cause fatal electric shock. A: Several amps B: Several milliamps C: hundreds of milliamps D: tens of milliamps 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 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 connects 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 protective neutral connection belongs to (c) system. A: It b:tt c:tn D: the voltage of three-phase three wire 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 and metal containers) and it is inconvenient to move, the voltage of portable lamp shall not exceed (a) v. A：36； 12 B：50； 42 C：110； 36 D：50； 36 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 (). A：N； PEN； PE B：PE； N； PEN C：N； PE； PEN D：PEN； N； PE answer: C leakage protection device is mainly used for (). A: Prevent personal electric shock accident B: prevent power interruption c2015 April 10: reduce line loss D: prevent electric leakage fire accident answer: A, D install lightning rods, lightning wires, lightning protection, lightning strip are the main measures to protect (). A: Lightning intrusion wave B: direct lightning strike C: counterattack D: secondary discharge answer: B () is the main measure 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 in general, human body resistance can be considered according to (). A: 50~100 Ω b:800~1000 Ω c:100~500 K Ω d:1~5 m Ω answer: B () electrical equipment is an electrical equipment that can withstand the explosion of internal explosive mixture 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 leakage protector whose rated leakage action current is () belongs to high sensitivity type. A: 30ma~1a b:30ma and below c:1a above d:1a answer: B 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 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: Allow interruptions B: do not allow interruptions C: allow access to switching appliances D: automatically cut off answer: B and professional after-sales service team. 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 symbol "return" is the auxiliary mark of (). A: Basic insulation B: double insulation C: functional insulation D: shielding answer: B overhead lines should not be crossed (). A: Buildings with burning materials as roofs B: roads C: navigable rivers D: Cableways answer: a 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 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 hazard D: both direct contact electric shock and issue a notice with the environmental protection department for indirect contact electric shock protection answer: D connect PE trunk line, grounding trunk line, water main pipe, gas main pipe, heating and air conditioning riser at the incoming line of the building power line, It is better to connect the metal components of the building with other metal pipes. This measure is called (). A: Overload protection B: main equipotential bonding C: non-conductive environment D: auxiliary equipotential bonding answer: B 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 clothes without electrostatic ignition hazard. When the relative humidity of the environment is maintained above 50%, cotton overalls can be worn. A: 0.25mj b:0.025mj c:0.0025mj d:0.00025mj answer: a explosive gas environment depends on the frequency of explosive gas mixture