Multiple-choice questions (1 point each, total 30 points) 1. See the following signs in the working environment, indicating () A. Pay attention to safety B. Beware of electric shock C. Beware of infection 2. According to international regulations, the voltage () volts or less does not need to consider the danger of preventing electric shock. A. 36 volts B. 65 volts C. 25 volts 3. The red line in the three-wire cable represents (). A. Zero line B. Live wire C. Ground wire 4. When the power is off and overhauled, which sign should be hung on the operating handle of the switch or knife gate that can be sent to the work site after closing? () A. "Working here" B. "Stop, high pressure danger" C. "No closure, someone is working" 5. Most electric shock accidents are caused by personal injury or death. A. The human body receives electric current and is shocked B. Burn C. Electric shock 6. If an electric shock is severe, and breathing stops or the heart stops beating, you should try to perform () and chest compression. A. Massage B. Acupoint C. Artificial respiration 7. What fire extinguishing method cannot be used when electrical appliances are on fire? () A. Use carbon tetrachloride or 1211 fire extinguisher B. Use sand C. Extinguish with water 8. The static electricity voltage can reach (), which can be discharged in the field, generating static sparks and causing fires. A. 50 volts B. Tens of thousands volts C. 220 volts 9. The use of a leakage protector is to prevent (). A. Electric shock accidents B. Voltage fluctuation C. Overload charge 10. What kind of adverse reactions will the operator have under the action of high-frequency electromagnetic fields for a long time? () A. Breathing difficulty B. Neurological disorders C. Fatigue 11. Which of the following fire extinguishers are suitable for electrical fires? () A. Carbon dioxide fire extinguisher B. Dry powder fire extinguisher C. Foam fire extinguisher 12. Which workplace is not suitable for using metal ladders? () A. A place where the motor can be touched B. Pit or enclosed space C. Working at height 13. When the high-voltage power line breaks, the person must not enter within () meters of the broken wire. A. 10 B. 20 C. 30 14. Which of the following precautions is correct when using a hand-held power tool? () A. Use a universal socket B. Use a leakage protector C. Work with wet body or clothes 15. The dangerous voltage for an electric shock accident generally starts from () volts. A. 24 B. 26 C. 65 16. When using electrical equipment, due to improper maintenance, when () enters, it may cause a short circuit accident. A. Conductive dust or fiber B. Strong light radiation C. Heat 17. When the fixed wire sockets in the factory are damaged, it will cause (). A. Inconvenience in work B. Unattractive appearance C. Electric shock 18. What is the voltage of the civil lighting circuit? () A. DC voltage 220 volts B. AC voltage 280 volts C. AC voltage 220 volts 19. When repairing a high-voltage motor, which of the following behaviors is wrong?() A. First implement the power-off safety measures, then carry out maintenance on the high-voltage motor and its accessories. B. At the end of the overhaul, when the high-voltage motor and its starting device need to be energized, all workers should evacuate the site first. C. Perform maintenance on the ground wire of the running high-voltage motor. 20. Which of the following statements about the use of leakage protectors is correct? () A. Leakage protector can protect personal safety and also supervise the insulation of low-voltage systems or equipment. B. The line after the leakage protector installation point cannot be insulated from the ground. C. In daily use, the leakage protector should not be pressed in the power-on state to check if it is sensitive or reliable. 21. What kind of safety technical measures are involved in the installation of leakage protectors? () A. Basic security measures B. Auxiliary security measures C. Absolute security measures 22. Under the influence of electromagnetic fields, the human body will suffer different degrees of damage. () A. Current B. Voltage C. Electromagnetic radiation 23. If the workplace is wet, to avoid electric shock, the person using a hand-held power tool should (). A. Stand on iron plate and operate B. Stand on insulating rubber mat and operate C. Wear anti-static shoes 24. Lightning discharge has the characteristics of (). A. High current and high voltage B. Low current and high voltage C. High current and low voltage 25. The height of the light and dark sockets in the workshop from the ground is generally not less than () meters. A. 0.3 m B. 0.2 m C. 0.1 m 26. What fire extinguishers cannot be used when fighting electrical equipment fires?() A. Carbon tetrachloride fire extinguisher B. Carbon dioxide fire extinguisher C. Foam fire extinguisher 27. Before touching any electrical equipment, it should be considered as () A. No electricity B. May have electricity C. Has electricity 28. What protective measures should be taken for electrical equipment used in accordance with safety regulations? A. None B. Protective zero or grounding C. Anti-rust paint 29. During the process of soldering and cutting electronic boards, what should be worn? (;). A. Wear protective glasses B. Wear ear protection C. Wear a hard hat 30. When workers are engaged in electrician operations and see the following signs, they indicate (). A. Pay attention to safety B. Beware of cables C. Beware of motor injury Fill in the blank questions (2 points each, total 20 points) 1. Protection and zero connection refers to the interconnection of the part of the electrical equipment that is not charged under normal conditions with the power grid. 2. Protective grounding is to closely connect the parts of the ground voltage that may present a dangerous situation in the event of a fault. 3. The human body is a conductor; when the human body comes into contact with two different points, due to the role, it will form in the human body, this phenomenon is electric shock. 4. From the way the human body touches the charged body and the way the electric current passes through the human body, the electric shock can be divided into: the person standing on the ground or other conductor, a certain part of the human body touches the charged body; the human body touches the two-phase charged body at the same time; the human body is near the ground, due to the step voltage acting between the two feet. 5. The leakage protector can be used for protection and can also be used to supervise the insulation condition of the system or equipment; the line after the installation point of the leakage protector should be insulated, and the line should be well insulated. 6. Repeated grounding means that one or more places on the zero line are reconnected with the earth. The safety function is to reduce the voltage of the leakage equipment; to reduce the danger of the broken line; to shorten the duration of the shell or ground short circuit; performance of overhead lines, etc. 7. For places prone to static electricity, keep the ground moist or lay a good ground; workers should wear clothes and shoes, and static electricity should be guided to the earth in time to prevent static electricity and sparks. 8. Static electricity has three major characteristics: one is high; the second is prominent; the third is serious. 9. The basic elements of electricity safety are, and so on, are the basic elements for ensuring the safety of electricity. As long as these elements meet the requirements of safety regulations, the safety of electricity under normal conditions can be guaranteed. 10. There are two types of current damage to the human body: that is, and. True or false questions (1 point each, total 20 points) 1. In an environment full of flammable gas, manual power tools can be used. () 2. When the household appliance is in use, the switch can be operated with wet hands. () 3. To prevent electric shock, technical measures such as insulation, protection, and isolation can be used to ensure safety. () 4. For places where static electricity is likely to occur, keep the floor moist or lay a floor with good conductivity. () 5. Electricians can wear anti-static shoes to work. () 6. In buildings close to the line or transformer, there may be signs of “no climbing, no electricity hazard†on the buildings that may be mistakenly climbed. () 7. When someone has a low-voltage electric shock, he should be pulled away immediately. () 8. In wet or hot places or with conductive dust, it should be powered by normal voltage. () 9. When lightning strikes, if the operator is isolated in the exposed area and feels the hair is erected, he should kneel down immediately, bend forward, and hold his knees with both hands. () 10. It is not necessary to turn off the power when cleaning the electric machine. () 11. Usually, women's body impedance is greater than that of men. () 12. There is no need to hang the nameplate on the surrounding columns of low-voltage equipment or pressure-resistant experiments. () 13. When the current is 100 mA, it is called lethal current. () 14. When moving some non-fixed installation electrical equipment (such as electric fan, lighting), you do not need to cut off the power. () 15. The average resistance of an average person is 5000 to 7000 ohms. () 16. When using hand-held power tools such as hand drills and electric grinding wheels, a leakage protector should be installed to ensure safety. () 17. A fuse should be installed on the protection line of the lighting circuit. () 18. For workers who work in flammable, explosive, or easily burned places with static electricity, chemical fiber protective equipment can be issued and used. () 19. Power tools should be regularly inspected and repaired by an electrician with qualified documents. () 20. The human body is electrocuted to death because the liver is seriously injured. () Short answer questions (5 points each, total 15 points) 1. Under what circumstances should the switch and the operation handle of the knife gate be marked with the sign "No closing, someone working"? 2. What are the basic measures to prevent AC and DC electric shocks? 3. What safety issues should be paid attention to when using electric drills or hand-held power tools? Essay question (10 points) What is the difference between protective grounding and protective zeroing? Case question (5 points) Liu Mei is an intern electrician in a company. She is learning a lot, but she still feels that she knows a lot. The master decided to test her knowledge. The master asked: "Do you know how much current is called lethal current?" Liu Mei thought for a moment and said, "About 200 mAh." The master asked again: "What kind of lamps should be used for lighting in the tunnel pressure vessel?" "Of course I know, I should use a high-quality general lighting." The master said: "Then you should say that the protection circuit of the lighting circuit should not be equipped with fuses?" Liu Mei said: "Of course not, because this will be wasted." What is Liu Mei’s statement wrong? What is correct? Answers to the electrical safety test questions 1. Multiple choice questions (1 point each, total 30 points) 1. B 2. C 3. B 4. C 5. A 6. C 7. C 8. B 9. A 10. C 11. A 12. A 13. B 14. B 15. C 16. A 17. C 18. C 19. C 20. A 21. A 22. C 23. B 24. A 25. A 26. C 27. C 28. B 29. A 30. B Fill in the blank questions (2 points each, total 20 points) 1. Metal protection zero line 2. Conductive earth 3. Potential potential difference current 4. Single-phase electric shock, two-phase electric shock, step voltage electric shock 5. Personal safety and low pressure to the ground 6. Grounding device is electrically shocked against lightning. 7. Wet, conductive, anti-static accumulation 8. Voltage, electrostatic induction, tip discharge 9. Electrical insulation, safety distance, equipment and its conductor current carrying capacity, obvious and accurate sign 10. Electric shock and electric shock True or false questions (1 point each, total 20 points) 1. × (No, it will produce sparks, it is easy to cause an explosion) 2. × (cannot) 3. √ 4. √ 5. × (must wear insulated shoes) 6. √ 7. × (First get him out of the power supply, use insulation to separate him) 8. × (should be powered by ultra low voltage) 9. √ 10. × (To prevent the machine from accidentally starting, turn off the power) 11. × (female body impedance is small) 12. × (The signboard must be hung with "stop, there is danger of electricity") 13. × (50 mA) 14. × (The power must be turned off first) 15. × (1000-1500 ohms) 16. √ 17. × (No, otherwise the lighting appliance will short-circuit to the ground due to leakage) 18. × (chemical fiber fabric is very easy to generate static electricity, cannot be used) 19. √ 20. × (is the heart) Short answer questions (5 points each, total 15 points) 1. Answer: 1) Once the switch is closed, the switch and knife switch can be sent to the work place. 2) Discontinued equipment, once closed, may cause the risk of personal electric shock, equipment damage or the switch or knife that causes the total leakage protector to operate. 3) Once closed, the two power systems will be juxtaposed or cause a reverse power switch or knife switch. 2. Answer: Set the necessary protection for live equipment, ensure that accidental contact and access are prevented, so that it is impossible to contact; for accidentally charged equipment, measures such as protective grounding and protection to zero or installation of leakage circuit breakers should be adopted; inspect, repair or test electrical wiring or electrical equipment. However, when it is necessary to carry out elective maintenance, appropriate personal protective equipment should be used. 3. Answer: (1) All conductive parts must have good insulation. (2) All wires must be tough and durable soft rubber threads. At the point where the wire enters the motor housing, a rubber ring is applied to protect the wire from abrasion. (3) The motor incoming line shall be equipped with a grounding or zeroing device. (4) In use, you must wear insulated shoes; wear protective gloves and other protective equipment. (5) Every time you use the tool, you must strictly check it. Essay question (10 points) Answer: Protective grounding and protective zeroing are two technical measures to maintain personal safety. The differences are: First, the protection principle is different. Protective grounding is suitable for general low-voltage ungrounded power grids and low-voltage grounding grids with other safety measures; protective grounding can also be used for high-voltage ungrounded power grids. Ungrounded grids do not have to be protected from zero. Third, the line structure is different. In addition to the phase line, the protective grounding system only has a protective ground wire. In addition to the phase line, the protection zero system must have a neutral line; if necessary, the protection zero line should be separated from the working zero line; its important device should also have a ground line. Case question (5 points) Answer: (1) The lethal current is 50 mA. (2) Illumination in tunnel pressure vessels should use special low voltage lighting. (3) The fuse should not be installed on the protection line, because when the lighting circuit is short-circuited due to leakage, the fuse on the protection line will be first blown, which will cause all metal casings to be charged, causing electric shock.
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