First, multiple-choice questions (1 point for each question, a total of 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, the voltage (C) volts need not be considered to prevent the danger of electric shock.
A. 36 volts B. 65 volts C. 25 volts
3. The red line in the three-wire cable represents (B).
A. Zero line B. FireWire C. Ground wire
4. When the power is off and overhauled, which of the following signs should be hung on the operating handle of the switch or knife gate that can be sent to the work site after closing? (C)
A. Work here" B. "Stop, high voltage danger" C. "No closure, some people work"
5. Most of the electric shock accidents are caused by (A) personal injury.
A. The human body receives electric current and is shocked. Burn C. Electric shock
6, if the electric shock is serious, breathing stops or the heart stops beating, you should try to perform (C) and chest compression.
A. Massage B. Acupoint C, artificial respiration
7. What is the following fire extinguishing method that cannot be used when the appliance is on fire? (C)
A. Use carbon tetrachloride or 1211 fire extinguisher to extinguish the fire. Use sand to extinguish fire C. Extinguish with water
8, the electrostatic voltage can be up to (B), can be discharged in the field, generate static sparks, causing fire.
A. 50 volts B. Tens of thousands volts C 220 volts
9. The use of the leakage protector is to prevent (A).
A. Electric shock accident B. Voltage fluctuation C. Charge overload
10. What adverse reactions will the operator have under the action of high-frequency electromagnetic fields for a long time? (C)
A. Difficulty breathing B. Neurological disorders Fatigue
11. Which of the following fire extinguishers are suitable for extinguishing electrical fires? (A)
A. Carbon dioxide fire extinguisher B. Dry powder fire extinguisher C. Foam fire extinguisher
12. What kind of workplace is not suitable for metal ladders? (A)
A. There is a workplace where the motor will be touched. Pit or closed place C. Working at height
13. When the high-voltage power line is broken, the wire is broken within the meter and the personnel are prohibited from entering. (B)
A. 10 B. 20 C. 30
14. Which of the following precautions is correct when using a hand-held power tool? (B)
A. Use universal socket B. Use leakage protector C. Wet body or clothes
15. The dangerous voltage at which an electric shock occurs is usually started from (C) volts.
A. 24 B. 26 C. 65
16. When using electrical equipment, if the maintenance is not timely, when (A) 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 (C).
A. Inconvenience caused by work B. Unsightly C. Electric shock
18. Which of the following is the civil lighting circuit voltage? (C)
A. DC voltage 220 volts B. AC voltage 280 volts C. AC voltage 220 volts
L9. When repairing the high voltage motor. Which of the following behaviors is wrong? (C)
A. First, implement the power-off safety measures, and then carry out maintenance work on the circuit of the high-voltage motor and its accessories.
B. At the end of the overhaul work, when the high-voltage motor and its starting device need to be energized, all the workers should be evacuated from the site and then sent for trial operation. C. Perform maintenance work 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)
A. The leakage protector can be used to protect personal safety and can also be used to supervise the insulation of the low voltage system 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 whether it is sensitive or reliable.
21. What kind of safety technical measures are involved in installing leakage protectors? (A)
A. Basic security measures B. Auxiliary security measures C. Absolute security measures
22. Under the action of electromagnetic field, the human body will cause different degrees of damage to the human body due to (C).
A. Current B. Voltage C. Electromagnetic radiation
23. If the workplace is wet, to avoid electric shock, the person using the hand-held power tool should (B).
A. Standing on the iron plate, operate B. Standing on the insulating rubber plate, operate C. Wear anti-static shoes
24. Lightning discharge has the characteristics of (A).
A. The current is large and the voltage is high. The current is small and the voltage is high. Large current, low voltage
25. The height of the light and dark sockets in the workshop from the ground is generally not less than (A) how many meters?
A. 0.3 m B. 0.2 m C. 0.1 m
26. What kind of fire extinguisher can I use when fighting electrical equipment fires? ( C )
A. Carbon tetrachloride fire extinguisher B. Carbon dioxide fire extinguisher C. Foam fire extinguisher
27. What is the (C) opinion of any electrical equipment before it is unidentified?
A. No electricity B. Maybe there is electricity C. Have electricity
28. What protective measures should be taken for the electrical equipment used in accordance with the relevant safety regulations? (B)
A. No B. Protective zero or ground C. Antirust paint
29, in the electronic bottom plate soldering, shearing and other processes should be (A).
A. Wear protective glasses B. Wear ear protectors C. Wear a hard hat
30. When workers are engaged in electrician operations, if they see the following signs, they indicate (B).
A. Pay attention to safety B. Beware of cable C. Beware of motor injury 2, fill in the blank question (2 points for each question, a total of 20 points)
1. Protection and zero connection means that the (metal) part of the electrical equipment that is not charged under normal conditions is connected to the grid (protected to zero).
2. The protective grounding is to connect the (large conductive) part of the ground voltage that may be dangerous under fault conditions to the (earth).
3. The human body is a conductor. When the human body comes into contact with two points with different (potential), due to the action of (potential difference), it will form (current) in the human body. This phenomenon is electric shock.
4. From the way the human body touches the charged body and the way the current passes through the human body, the electric shock 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 can also be used to supervise the (low-voltage) system or equipment (ground) insulation condition; the line after the leakage protector installation point should be (to the ground) Insulated, the line should be well insulated.
6. Repeated grounding means that one or more passes on the zero line (grounding device) are reconnected to the earth. The safety function is to reduce the voltage of the leakage equipment (to the ground) and reduce the risk of electric shock when the neutral line is broken. ; shorten the duration of the shell or ground short circuit; improve the (lightning) performance of overhead lines.
7. For places that are prone to static electricity, keep the ground (wet) or lay (electrically conductive) ground; workers should wear (anti-static) clothes and shoes, accumulate static electricity and guide the earth in time to prevent static electricity. Produce a spark.
8, static has three major characteristics: First, (high pressure) high; Second, (static induction) prominent; Third, (tip discharge) phenomenon is serious.
9. The basic elements of electricity safety are (electrical insulation), (safe distance), (equipment and its conductor current carrying capacity), (obvious and accurate signs), etc. are the basic elements to ensure 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.
L0, there are two types of current damage to the human body: (electric shock) and (electric shock).
Third, the judgment question (1 point for each question, a total of 20 points)
l In the environment full of flammable gas, manual power tools can be used. ( x )
2. When the household appliance is in use, the switch can be operated with wet hands. ( x )
3. In order 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 electrical conductivity. ( √ )
5, electricians can wear anti-static shoes work. ( x )
6. In the buildings that are close to the line or the 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. ( x )
8. In places where it is wet or hot or has conductive dust, it should be powered by normal voltage. ( x )
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. ( x )
11. Usually, women's body impedance is greater than that of men. ( x )
12. There is no need to hang the nameplate on the surrounding columns of low-voltage equipment or pressure-resistant experiments. ( x )
l 3, when the current is 100 mA, it is called lethal current. ( x )
14. When moving some non-fixed installation electrical equipment (such as electric fan, lighting), you do not need to cut off the power. ( x )
15. The average resistance of an average person is 5000 to 7000 ohms. ( x )
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. ( x )
18. For workers who work in places that are flammable, explosive, easy to burn and have static electricity, chemical fiber protection products (x) can be issued and used.
19. Power tools should be inspected and repaired regularly by qualified electricians ( √ )
20. The human body is electrocuted to death because the liver is seriously injured. ( x )
Fourth, short answer questions (5 points for each question, a total of 15 points)
1. Under what circumstances, the switch and the operation handle of the knife gate must be hanged with the signboard that is forbidden to be closed, someone is working!
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. #p#分页头#e#
2. What are the basic measures to prevent AC and DC electric shock?
Answer: Set the necessary protection for live equipment, and ensure that accidental contact and accidental 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. What are the safety issues to be aware of when using an electric drill or hand-held power tool?
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.
Five, essay questions (each question lo points, a total of 10 points)
What is the difference between protective grounding and protective zeroing?
Answer: Protective grounding and protective zeroing are two technical measures to maintain personal safety. The differences are:
First, the protection principle is different. The basic principle of the protection grounding of the low-voltage system is to limit the grounding voltage of the leakage device so that it does not exceed a certain safety perimeter; the protection grounding of the high-voltage system, in addition to limiting the voltage to the ground, in some cases, the protection device in the enabling system The role of the action. The main function of the protection zero is to make the single-phase short circuit of the equipment by the zero line, and the protection device on the line can move quickly.
Second, the scope of application is different. The protective earthing is suitable for general low-voltage ungrounded power grids and low-voltage grounding grids with other safety measures; protective earthing 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.
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