First, multiple-choice questions (65438+ 0 points for each question, ***30 points)
1. See the following signs in the working environment, indicating (b) A. Pay attention to safety B. Beware of electric shock C. Beware of infection.
2, international regulations, voltage (C) volts below don't have to consider to prevent the danger of electric shock. 36 volts B.65 volts C.25 volts
3. The red line in the three-wire cable represents (B). A. neutral line B. live line C. ground line
4. During power outage maintenance, which of the following signs should be hung on the operating handle of the switch or circuit breaker, and once it is closed, it can be sent to the work place? (c) A. Work here "B. Stop, high voltage danger" C. "No closing, someone is working"
5, electric shock accidents, the vast majority of (a) lead to personal injury or death. A. The human body receives electric current and receives electric shock. B. Burn C. Electric shock
6, if the electric shock is seriously injured, breathing stops or the heart stops beating, should try to implement (c) and chest compressions.
A. Massage B. Acupoints C. Artificial respiration
7. Which of the following fire extinguishing methods can't be used when the electrical appliance is on fire? (3)
A. put out the fire with carbon tetrachloride or 12 1 1 fire extinguisher B. put out the fire with sand C. put out the fire with water.
8, the highest electrostatic voltage can reach (b), can be discharged at the scene, produce electrostatic sparks, cause a fire. A.50 volts B. Tens of thousands of volts C 220 volts
9, the use of leakage protector is to prevent (a). A. Electric shock accident B. Voltage fluctuation C. Charging overload
10, what adverse reactions will the operator have under the action of high-frequency electromagnetic field for a long time? (3)
A. Dyspnea B. Neuropathy C. Fatigue and weakness
1 1. Which of the following fire extinguishers is suitable for extinguishing electrical fires? (a) Carbon dioxide fire extinguisher B. Dry powder fire extinguisher C. foam extinguisher
12, metal ladders are not suitable for the following workplaces? (1)
A. workplaces with electric shock opportunities B. pits or closed places C. aerial work
13. When the high-voltage wire is disconnected on the ground, personnel are forbidden to enter within a few meters of the disconnection point. (B ) A. 10
14. Which of the following precautions is correct when using hand-held power tools? (2)
A. use a universal socket B. use a leakage protector C. wet your body or clothes.
15, the dangerous voltage of electric shock accidents generally starts from (C) volts. A.24 B.26 C.65
16. When using electrical equipment, due to untimely maintenance, when (a) enters, it may lead to a short circuit accident.
A. conductive dust or fibers B. strong light radiation C. hot air
17, when the fixed wire socket in the factory is damaged, it will cause (c). A. it brings inconvenience to work. B. it's not pretty. C. Electric shock injury
18, which of the following is the voltage of civil lighting circuit? A. DC voltage is 220 volts. B. AC voltage is 280 volts. C. AC voltage is 220 volts.
L9, maintenance of high voltage motor. Which of the following behaviors is wrong? (3)
A. Implement power failure safety measures first, and then repair the circuits of high-voltage motors and their accessories.
B. When it is necessary to power on the high-voltage motor and its starting device after the overhaul, let all personnel leave the site first, and then send power for trial operation. C. Maintain the grounding wire of the running high-voltage motor.
20. Which of the following statements about using leakage protector is correct? (1)
A. Leakage protectors can be used to protect personal safety, and can also be used to supervise the grounding insulation of low-voltage systems or equipment. B the line behind the installation point of leakage protector shall not be insulated from the ground.
C. In daily use, the leakage protector should not press the experimental button when it is energized to test whether it is sensitive and reliable.
2 1, install leakage protector, which is the safety technical measure? (1)
A. Basic safety measures B. Auxiliary safety measures C. Absolute safety measures
22, the human body under the action of electromagnetic field, because (c) will make the human body by different degrees of damage. A. Current B. Voltage C. Electromagnetic wave radiation
23, if the workplace is wet, in order to avoid electric shock, people who use hand-held power tools should (b).
A. stand on the iron plate for operation B. stand on the insulating rubber plate for operation C. wear anti-static shoes for operation.
24, lightning discharge has the characteristics of (a). A. high current and high voltage B. low current and high voltage C. high current and low voltage
25, the light and dark sockets in the workshop are generally not less than (a) how many meters from the ground?
A.0.3 B.0.2 C.0. 1m
26, electrical equipment, fire extinguishing, what can't use a fire extinguisher? (3)
A. Carbon tetrachloride fire extinguisher B. Carbon dioxide fire extinguisher C. foam extinguisher
27, any electrical equipment before there is no electricity, how (c) thinking? A. There is no electricity. B. Maybe there is electricity. C. There is electricity.
28, the use of electrical equipment in accordance with the relevant safety regulations, the shell should have what protective measures? (2)
A. No B. Protective grounding or grounding C. Rust-proof paint
29.(a) should be used in the electronic backplane welding and foot cutting process. A. Wear protective glasses B. Wear ear protectors C. Wear a helmet.
30, workers engaged in electrical work, such as see the following signs, said (b). A. Pay attention to safety. B. Watch out for cables. C. Watch out for motor injuries.
Fill in the blanks (2 points for each question, 20 points for * * *)
1, protection to zero refers to the neutral (metal) part of electrical equipment and power grid (protection to zero) interconnection.
2. Protective grounding is to closely connect the (conductive) part of voltage with (earth), which may be dangerous under fault conditions.
3. The human body is a conductor. When the human body touches two points with different potentials, (current) will form in the human body due to the effect of (potential difference). This phenomenon is electric shock.
4. The way of electric shock contacting charged body from human body and the way of current passing through human body can be divided into: (single-phase electric shock), (two-phase electric shock) and (step voltage electric shock).
5. The leakage protector can be used to protect (personal safety) and supervise (low voltage) the insulation state of the system or equipment. The line behind the installation point of leakage protector should be insulated (to ground), 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 through (grounding device), and its safety function is to reduce the voltage of leakage equipment (to ground); Reduce the risk of electric shock when the zero line is broken; Shorten the duration of shell collision or ground short circuit; Improve the lightning protection performance of overhead lines.
7. For places prone to static electricity, keep the ground (wet) or lay the ground with good (conductive) performance; Workers should wear (anti-static) clothes and shoes, accumulate static electricity and guide people to the earth in time to prevent static electricity and sparks.
8. Static electricity has three characteristics: one is high (high voltage); The second is (electrostatic induction) protrusion; Third, the phenomenon of tip discharge is serious.
9. The basic elements of electricity safety are (electrical insulation), (safe distance), (current carrying capacity of equipment and its conductors) and (obvious and accurate signs). As long as these elements can meet the requirements of safety regulations, the safety of electricity consumption under normal circumstances can be guaranteed.
L0。 There are two kinds of harm caused by electric current to human body: (electric shock) and (electric injury).
Three. True or false questions (65438+ 0 points for each question, ***20 points)
L, in an environment full of combustible gas, you can use manual power tools. (10)
2, household appliances in the use process, you can use wet hands to operate the switch. (10)
3. In order to prevent electric shock, technical measures such as insulation, protection and isolation can be taken to ensure safety. ( √ )
4. For places prone to static electricity, keep the ground moist or lay a floor with good conductivity. ( √ )
5. Electricians can wear antistatic shoes to work. (10)
6. A sign "No Climbing, Electrical Danger" must be hung on buildings close to lines or transformers that may climb by mistake. ( √ )
7. When someone gets an electric shock at low voltage, pull it away immediately. (10)
8. In places with damp, high temperature or conductive dust, normal voltage should be used for power supply. (10)
9. When lightning strikes, if the operator is isolated in the exposed area and feels his hair stand on end, he should kneel down immediately, bend forward and hold his knees with his hands. ( √ )
10, clean the motor without turning off the power supply. (10)
1 1. Generally speaking, the human impedance of women is greater than that of men. (10)
12. Signs may not be hung around low-voltage equipment or withstand voltage test columns. (10)
L 3。 When the current is 100 mA, it is called fatal current. (10)
14. When moving some unfixed electrical equipment (such as electric fans and lighting lamps), it is not necessary to cut off the power supply. (10)
15, the average resistance of ordinary people is 5000-7000 ohms. (10)
16. When using hand-held electric tools such as hand drills and electric grinding wheels, leakage protectors should be installed to ensure safety. ( √ )
17, fuse should be installed on the protection line of lighting circuit. (10)
18. Chemical fiber protective articles (X) can be distributed to workers working in flammable, explosive, flammable and static places.
19. Electric tools should be regularly inspected and maintained by qualified electricians with certificates (√).
20. The human body died of electric shock because the liver was seriously damaged. (10)
4. Short answer questions (5 points for each question, *** 15 points)
1. Under what circumstances, the operating handles of switches and circuit breakers should be hung with "No closing, someone is working! Signboard?
Answer: 1) Switches and knives that can send electricity to the workplace once closed. 2) Once the equipment has stopped, there is a danger of personal electric shock caused by switches and knife switches, and the equipment is damaged or the total leakage protector acts. 3) Once closed, the two power supply systems will be connected in parallel or power transmission will be reversed.
2. What are the basic measures to prevent AC and DC electric shock?
Answer: Electrified equipment should provide necessary protection, and it is required to ensure that accidental contact and accidental approach are prevented, making contact impossible; For occasionally charged equipment, measures such as protective grounding and protective grounding or installation of leakage circuit breakers should be taken; In addition, it is necessary to inspect, repair or test circuits or electrical equipment. However, when live maintenance is required, appropriate personal protective equipment should be used.
3. What safety issues should be paid attention to when using electric drills or hand-held power tools?
Answer: (1) All conductive parts must be well insulated. (2) All wires must be tough and durable soft rubber wires. When the wire enters the motor housing, it should be protected by rubber ring to prevent the wire insulation layer from being worn. (3) The incoming line of the motor shall be equipped with grounding or zero connection device. (4) Insulating shoes must be worn when using; Wear protective equipment such as insulating gloves. (5) Every time a tool is used, it must be strictly checked.
Verb (abbreviation of verb) essay questions (each question is marked with lo, *** 10).
What is the difference between protective grounding and protective grounding?
Answer: Protective grounding and protective grounding are two technical measures to maintain personal safety. Their differences are as follows:
First, the protection principle is different. The basic principle of low-voltage system protective grounding is to limit the voltage of leakage equipment to the ground so that it does not exceed a certain safety range; The protective grounding of high voltage system not only limits the voltage to the ground, but also promotes the action of protective devices in the system in some cases. The main function of protection zero connection is to make the equipment form a single-phase short circuit by connecting the zero line, and promote the rapid action of the protection device on the line.
Second, the scope of application is different. Protective grounding is suitable for general low-voltage ungrounded power grids and low-voltage grounded power grids with other safety measures; Protective grounding can also be used in high voltage ungrounded power grid. The ungrounded power grid does not need to adopt protective zero connection.
Third, the line structure is different. In addition to the phase line, the protective grounding system only has protective ground wire. In addition to the phase line, the zero protection system must have a zero line; When necessary, the protective zero line should be separated from the working zero line; Its important devices should also be grounded.