First, multiple-choice questions (1 point for each question, a total of 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 send power to the work area after closing?
A. "Working here"
B. "Stop, high voltage 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 the electric shock is severe, with breathing stopped or heart stopped, you should try to perform () and chest compression.
A. Massage
B. Acupuncture
C. Artificial respiration
7. Which of the following fire extinguishing methods cannot be used when electrical equipment is on fire?()
A. Use carbon tetrachloride or 1211 fire extinguisher
B. Use sand to extinguish
C. Extinguish with water
8. The static voltage can reach (), which can discharge in the field, generate static sparks, and cause fires.
A. 50 volts
B. Tens of thousands of volts
C. 220 volts
9. The use of a residual current device (RCD) is to prevent ().
A. Electric shock accidents
B. Voltage fluctuations
C. Overload of charge
10. What kind of adverse reactions will an operator experience after being exposed to high-frequency electromagnetic fields for a long time?
A. Difficulty breathing
B. Neurological disorders
C. Fatigue
11. Which of the following fire extinguishers is suitable for extinguishing 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 may be touched
B. Pit or enclosed space
C. Working at height
13. When a high-voltage power line breaks, within how many meters should personnel be prohibited from entering?
A. 10
B. 20
C. 30
14. Which of the following precautions is correct when using a handheld power tool?
A. Use a universal socket
B. Use a leakage protector
C. Work with wet body or clothes
15. What is the dangerous voltage for an electric shock accident generally starting at?
A. 24 volts
B. 26 volts
C. 65 volts
16. When using electrical equipment, due to improper maintenance, when () enters, it may cause a short circuit.
A. Conductive dust or fibers
B. Strong light radiation
C. Heat
17. If the fixed wiring 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 220 volts
B. AC 280 volts
C. AC 220 volts
19. When repairing a high-voltage motor, which of the following behaviors is wrong?
A. First implement power-off safety measures, then carry out maintenance on the high-voltage motor and its accessories.
B. At the end of the maintenance, when energizing the high-voltage motor and its starter, all workers should evacuate the site before testing.
C. Perform maintenance on the ground wire of a running high-voltage motor.
20. Which of the following statements about the use of RCDs is correct?
A. RCDs can protect personal safety and also monitor the insulation condition of low-voltage systems or equipment.
B. The line after the RCD installation point must not be insulated from the ground.
C. In daily use, the RCD should not be tested under power-on conditions to check its sensitivity and reliability.
21. What type of safety technical measures are involved in the installation of RCDs?
A. Basic safety measures
B. Auxiliary safety measures
C. Absolute safety measures
22. Under the influence of electromagnetic fields, the human body may 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 handheld power tool should:
A. Stand on an iron plate and operate
B. Stand on an 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 how many meters?
A. 0.3 m
B. 0.2 m
C. 0.1 m
26. What fire extinguisher 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 according to relevant safety regulations?
A. None
B. Protective zero or grounding
C. Anti-rust paint
29. During the process of soldering, shearing, and other operations on the electronic baseplate, what should be worn?
A. Protective glasses
B. Ear protection
C. 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 injuries
Second, fill-in-the-blank questions (2 points per question, a total of 20 points)
1. Protection and zero connection refers to connecting the non-charged part of the electrical equipment to the power grid under normal conditions.
2. Protective grounding involves closely connecting parts that may present a dangerous voltage during faults to the ground.
3. The human body is a conductor. When the body touches two different points, due to the potential difference, current flows through the body, causing electric shock.
4. Electric shocks can be divided into: single-phase electric shock, two-phase electric shock, and step voltage electric shock.
5. The RCD can be used for protection and can also monitor the insulation status of the system or equipment. After the RCD is installed, the line should be well insulated.
6. Repeated grounding means re-connecting one or more places on the neutral line to the earth. Its safety functions include reducing the voltage of the leaking equipment, reducing the danger of broken lines, shortening the duration of shell-to-ground short circuits, and improving overhead line performance.
7. In places prone to static electricity, keep the floor moist or lay a conductive floor. Workers should wear clothing and shoes that can guide static electricity to the ground to prevent static sparks.
8. Static electricity has three major characteristics: high voltage, prominent effect, and serious consequences.
9. The basic elements of electrical safety include insulation, safety distance, and equipment current carrying capacity. As long as these meet safety requirements, electrical safety under normal conditions can be ensured.
10. There are two types of current effects on the human body: electric shock and electric burn.
Third, true/false questions (1 point per question, a total of 20 points)
1. Manual power tools can be used in environments full of flammable gas. ()
2. It is safe to operate switches with wet hands when using household appliances. ()
3. To prevent electric shock, measures such as insulation, protection, and isolation can be used. ()
4. In areas where static electricity is likely to occur, keep the floor moist or install a conductive floor. ()
5. Electricians can wear anti-static shoes to work. ()
6. In buildings near power lines or transformers, there may be signs like “no climbing, no electricity hazard.†()
7. If someone is electrocuted by low voltage, they should be pulled away immediately. ()
8. In wet or hot places with conductive dust, normal voltage should be used. ()
9. When lightning strikes, if an operator is isolated and feels their hair stand up, they should kneel down and hold their knees. ()
10. It is unnecessary to turn off the power when cleaning an electric machine. ()
11. Women's body resistance is usually higher than men's. ()
12. There is no need to hang nameplates around low-voltage equipment or pressure test areas. ()
13. A current of 100 mA is called a lethal current. ()
14. When moving non-fixed electrical equipment (like fans), the power does not need to be turned off. ()
15. The average resistance of a person is 5000 to 7000 ohms. ()
16. When using hand-held tools like drills or grinders, a leakage protector should be installed. ()
17. Fuses should be installed on the protective line of the lighting circuit. ()
18. For workers in flammable, explosive, or static-prone areas, chemical fiber protective gear can be issued. ()
19. Power tools should be regularly inspected and repaired by qualified electricians. ()
20. People die from electric shock because the liver is seriously injured. ()
Fourth, short answer questions (5 points per question, a total of 15 points)
1. Under what circumstances should the switch and the operation handle of the knife gate be marked with the label “No closure, someone is working�
Answer: 1) When the switch is closed, it can send power to the work location. 2) When the equipment is disconnected, closing it could risk electric shock or damage. 3) When closing could cause reverse power or system misoperation.
2. What are the basic measures to prevent AC and DC electric shocks?
Answer: Install necessary protections on live equipment to prevent accidental contact. For accidentally charged equipment, use protective grounding, zeroing, or RCDs. When inspecting or testing electrical equipment, use proper personal protective equipment.
3. What safety issues should be considered when using an electric drill or hand-held power tool?
Answer: Ensure all conductive parts have good insulation. All wires should be durable and flexible. Protect the wire entry point with a rubber ring. Install grounding or zeroing devices. Wear insulated shoes and gloves. Inspect the tool before each use.
Fifth, essay questions (10 points per question, a total of 10 points)
What is the difference between protective grounding and protective zeroing?
Answer: Protective grounding and protective zeroing are both safety measures. Their differences are: 1) Principle: Protective grounding uses the earth to limit voltage, while protective zeroing connects to the neutral line to create a short circuit. 2) Application: Protective grounding is used in ungrounded systems, while protective zeroing is used in grounded systems. 3) Structure: Protective grounding only requires a ground wire, while protective zeroing needs a neutral line and possibly a separate ground wire.
Sixth, case questions (5 points per question, a total of 5 points)
Liu Mei is an intern electrician. She learned a lot but still thought she knew everything. Her master decided to test her knowledge. He asked, “Do you know how much current is considered lethal?†Liu Mei answered, “About 200 mAh.†The master asked, “What kind of lamps should be used in a tunnel pressure vessel?†Liu Mei said, “High brightness general lighting.†The master replied, “You said the protection circuit shouldn’t have a fuse?†Liu Mei said, “Because it would be wasted.â€
What was wrong with Liu Mei’s statement? What is correct?
Answer: (1) Lethal current is 50 mA. (2) Special low-voltage lighting should be used in tunnels. (3) Fuses should not be installed on the protection line, as it could lead to electric shock if a fault occurs.
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