Coal mine underground electrician exam title answer - Solutions - Huaqiang Electronic Network

Second, multiple choice questions
1. The following power users (powered devices) belong to the first-level user (), and belong to the second-level user ().
A, mining substation B, main ventilator C, main shaft lifting equipment D for lifting personnel, rectification equipment E for underground electric vehicle, air compressor station F, main drainage pump G, mine hospital H, passenger tram
2. Cables must be used from the substation of the mining area to the distribution point of the mining face. ()
A, aluminum package B, copper core C, aluminum core
3. In the outburst area of gas emission, high gas mine, coal (rock) and gas (carbon dioxide), the local ventilator of the excavation face should be powered by ().
A, three special (special transformer, special switch, special line) B, power supply circuit C with selective leakage protection device, separate from the coal mining face
4. The control button of the shearer must be set on the () side and a protective cover.
A. By the coal wall B, by the goaf C, above the unit
5. When the mobile electric locker goes down, it must carry portable ().
A, optical methane detector B, methane detector C, methane detection alarm
6. The coal roadway, semi-coal rock roadway and mine roadway with gas mines that do not have the mine safety monitoring system must be equipped ().
A, methane power-off instrument B, methane wind power blocking device C, methane power-off device and wind power blocking device
7. The electric fitter in the coal and gas outburst mine should be equipped with () self-rescuer.
A, filter B, compression C, chemical oxygen
8. When a fire occurs in a single-headed alley, the local fan that is operating should ().
A, stop running B, keep running
9. It is strictly forbidden to use the local ventilator above () to supply air to a boring work surface at the same time.
A, 2 B, 3 C, 4
10. When the gas concentration in the airflow within 20 meters near the motor and its switch installation location reaches (), the work must be stopped, the power supply must be cut off, and the personnel should be evacuated for disposal.
A, 1.0% B, 1.5% C, 2.0%
11, the mine one pass three anti-finger to strengthen ventilation, anti-gas, fire, ().
A, anti-cold top B, waterproof disaster C, anti-dust
12. The transformer should be selected in a mine with a gas explosion hazard.
A, oil immersion B, mine explosion-proof dry C, power transformer
13. The calculation method of short-circuit current is ().
A, economic current method B, formula method C, graphic method
14. Electrical equipment should be used for lighting fixtures in the return airway of the mining area of the high gas mine.
A, mine general type B, mine explosion-proof type C, mine increased safety type
15. High-voltage motors in the main air intake of high gas mines should be equipped with () electrical equipment.
A, mine general type B, mine explosion-proof type C, mine increased safety type
16. In the mining face and other roadways, when the accumulated gas concentration in the space larger than 0.5ms reaches (), the work must be stopped within 20 meters, the power supply is cut off, and the personnel are evacuated for treatment.
A, 1.0% B, 1.5% C, 2.0% D, 5.0%
17. After the exhaust gas is exhausted, the power supply of the electrical equipment in the air supply duct of the local ventilator and the power supply in the return air system of the mining area can be manually restored only when the gas concentration in the airflow of the restored ventilation tunnel does not exceed ().
A, 0.5% B, 1.0% C, 1.5%
18. For electrical equipment whose power supply is cut off in excess of the specified concentration, the gas concentration must be reduced to () meters or less before the power can be turned on.
A, 0.5% B 1.0% C, 1.5%
19. The minimum electrical clearance for electrical equipment with a voltage of 220V shall be mm.
A, 4 B, 6 C, 8
20. In the circuit with two resistors connected in parallel, the calculation formula of the equivalent resistance R should be ().
A, R = R1 + R2 B, R = R1 × R2 / (R1 + R2)
C, 1/R: 1/R1+1/R2
21, in the gas mine, measuring the grounding resistance commonly used ().
A, buck type B, power method C, special resistance tester method
D, bridge method
22. When measuring the AC voltage with a multimeter, the black test pen should be inserted into the () jack.
A, "one" B, "ten"
23. The voltage protection of underground electrical equipment includes ().
A, under voltage protection B, single phase voltage protection C, over voltage protection
24. When measuring the circuit voltage with a multimeter, the instrument should be phased with the load.
A, series B, series or parallel C, parallel
25. Mobile and hand-held electrical equipment should use () cable.
A, rubber sleeve B, MVV type plastic force C special rubber sleeve
26. The fireproof iron door of the electromechanical chamber should be opened.
A, inward B, outward C, inward or outward
27, explosion-proof gas equipment before the well, should check its product certificate, explosion-proof certificate, () and safety performance.
A, production license B, safety sign C, safety license
28. The coal electric drill comprehensive protection device shall conduct a trip test every ().
• A, class B, day C, week
29. Ordinary belt electrical measuring instruments must be used below the gas concentration ().
A, 0.5% B, 1•0% C, 1.5%
30. In the coal flow face, the oxygen concentration shall not be lower than ()
A, 18% B, 20% C, 21%

Third, the judgment question
1. The current of each series resistor in the series circuit is the same, and the total resistance is the sum of the respective resistors. ()
2. The voltage across the resistors in the parallel circuit is equal to the power supply voltage, and the total resistance is the sum of the sub-resistors ()
3. When measuring voltage and current with a multimeter, do not touch the transfer switch with power. ()
4. The "Procedure" stipulates that under normal circumstances, the mine power supply should adopt a split operation mode. When the first circuit is running, the other circuit can be used without power to ensure the continuity of the power supply ()
5. It is strictly forbidden to install a load doser on the mine power line. ()
6. The other loads on the two-circuit power line of the mine must be reported to the mine manager for approval. ()
7. The neutral point of the distribution transformer under the forbidden well is directly grounded. ()
8. When repairing or relocating electrical equipment and cables, it is necessary to cut off the power supply and check the gas. When the gas concentration in the roadway is less than 1.5%, use the electroscope that matches the power supply. If the inspection is invalid, the conductor can be used. Discharge to the ground. ()
9. Megohmmeter is an instrument used to measure the insulation resistance and voltage of wires, cables and transformers, electrical equipment and electrical equipment. ()
10. The protection ring of the shaker is connected to the negative pole of the generator through the wire, so as to avoid the surface leakage power of the insulator affecting the measurement result. ()
11. When a local ventilator supplies air to two boring faces working at the same time, safety measures must be taken. ()
12. In the high-voltage circuit, the isolating switch cannot break the load current, and only the circuit breaker can break the load current. ()
13. Mine low-voltage feed switch is a kind of manual closing power supply switch. When the line has over-current and leakage faults, it can automatically trip to cut off the power. ()
14. When the cable and the air duct are installed on the side of the roadway, the cable should be firmly suspended under the air duct, but it is strictly prohibited to hang any objects on the cable. ()
15. When the cable is laid on the same side as the gas drainage pipeline, the cable should be laid on the pipe and kept at a distance of more than 3 meters. ()
16. The winding lane of the lift personnel and the winch lanes used for lifting materials and pedestrians shall not exceed 30 meters. ()
17, underground explosion-proof type of communication, signal and control devices, should be preferred to use mining increased safety. () (Editor: Electrician Network)

18. The explosion of explosion-proof electrical equipment means that the mining electrical equipment loses its flameproofness. ()
19. Clearance is the shortest air distance between two bare conductors. ()
20. Creepage distance is the shortest distance between two conductors along the surface of a solid material. ()
21. The basic requirement for the setting of the operating current of the electromagnetic overcurrent relay in the low-voltage power grid is that the protection should be able to operate reliably when the minimum two-phase short circuit occurs in the protected equipment. ()
22. Overvoltage refers to the phenomenon that the voltage that threatens the insulation of electrical equipment rises more than 20% of the rated voltage during the operation of the power supply system. ()
23, the over-voltage of coal mine underground can be divided into operating over-voltage, arc-grounding over-voltage and resonant over-voltage according to its nature. ()
24. The "Procedure" stipulates that the metal casing, the frame, the steel strip or the steel wire of the armored cable or the lead wire or the shield sheath of the electrical equipment which may be dangerously damaged due to insulation damage must have protective grounding. ()
25. The local grounding electrode installed in the ditch shall be not less than 0,6m2, and the thickness shall not be less than 2mm steel plate or steel pipe with the same effective area. ()
26. It is forbidden to connect several devices in series, but several grounding parts can be connected in series. ()
27. Safety spark-type instruments should be used when measuring downhole grounding resistance in mines with gas and coal dust explosion hazards. ()
28. It is strictly forbidden to use bulbs for heating and using electric furnaces. ()
29, when the electrical equipment is on fire, the power should be cut off first, before the power is cut off, only use non-conductive fire-fighting equipment to extinguish the fire. ()
30. The underground flow electric fitter must carry a portable gas detection alarm. ()
31. Filter self-rescuing devices must be worn when mines with coal and gas outburst dangers. ()
32. The underground electrician must pass the training and obtain the special work operation qualification certificate and be certified to work. ()
33. It is strictly forbidden to enter the roadway without ventilation or poor ventilation. ()
34. Located in the electromechanical chamber of the return air flow, the gas concentration in this return air flow shall not exceed 1.0%. ()
35. The concentration of hydrogen in the downhole charging chamber airflow and local accumulation shall not exceed 0.5%. ()
36. When using the local ventilation fan to vent the working face, when the wind is stopped due to maintenance or power failure, the personnel must be evacuated and the power supply must be cut off. ()
37. Before the local ventilator that has stopped running for some reason, the gas must be inspected. Only when the gas concentration in the airflow within 10 meters of the local ventilator and its switch does not exceed 1%, the local ventilation can be manually turned on. machine. ()
38. For electrical equipment whose power supply is cut off in excess of the specified concentration, the gas concentration must be reduced to 1, 0% or less before powering on. ()
39. When the gas concentration in the airflow within 20 meters near the motor or its switch installation site reaches 1%, it must stop working, cut off the power supply, and evacuate the personnel for disposal. ()
40. It is strictly forbidden to work in the area where the wind is stopped or the gas is out of limits. ()
41. Underground explosive materials must be equipped with explosion-proof (except mine-enhanced type) lighting equipment. It is strictly forbidden to install lamps in the chamber or wall tank where explosive materials are stored. ()
42. The lighting voltage of the underground explosive material library shall not exceed 220V. ()
43. No one may carry a miner's lamp into the underground explosive material store. ()
44. When multi-level transportation of inclined wells, the signals sent by each level must be different. ()
45. Explosion-proof electrical equipment should be inspected before the well, and the “product certificate”, “explosion-proof certificate”, “coal mine product safety mark” and safety performance should be checked. ()
46. Pipes that are introduced (exited) from the track and open-air overhead of the direct manhole on the ground must have a good centralized grounding of the metal body at not less than two places near the wellhead. ()
47. Communication lines must be equipped with fuses and lightning protection devices at the wells. ()
48. When a single-loop power supply is used for a mine with an annual output of less than 60,000 tons, there must be a backup power supply; the capacity of the backup power supply must meet the requirements for drainage and lifting;
49. The operation of the low-pressure leak detection device must be tested once a week. ()
50. The five major natural disasters in coal mines refer to disasters such as roof, gas, fire, electricity and water. ()

Fourth, the question and answer questions
1. What are the principles for selecting the cross section of the cable?
2. What are the requirements for power supply to the local ventilator?
3. What should you pay attention to when using a megohmmeter?
4. How to identify the non-flame-retardant rubber cable for mining on the ground?
5. How to determine the cable phase-to-phase short circuit fault?
6. Briefly explain the causes and preventive measures of cable phase failure.
7. What is the explosion of explosion-proof electrical equipment?
8. What regulations should be followed for operating downhole electrical equipment?
9. What regulations should be followed for maintenance or relocation of underground electrical equipment?
10. What are the causes of common phase-to-phase short-circuit faults?
11. What are the main hazards of leakage faults?
12. What is the role of protective grounding?
13, a switch with 10Kw motor, the system voltage is 660v, the power factor of the motor is: 0.86, please choose to protect the melt of the motor.
14. How does shielded cable improve power supply security?
15. What are the links and main equipment of the mine power supply system?
16. What are the main primary loads in coal mines?
17. What are the characteristics of the resistor parallel circuit?
18. What are the components of the underground protective earthing network?
19. What are the regulations on the location and space of the distribution points of the mining face?
20. How can I become a qualified electrician?

Answers to the underground electrician test questions 1. Fill in the blanks:
1, power, load, intermediate links
2, transmission voltage, power distribution
3, series, parallel, mixed
4, star (Y), triangle (厶)
5, three-phase three-wire
6, DC current, DC voltage, AC current, AC voltage, resistance
7, insulation resistance
8, running, charged
9, insulated boots, insulated gloves, insulation
10, non-combustible materials, outside
11. Equipment maintenance, roadway transportation, non-combustible materials
1 B 6
13, inspection, safety signs,
14, mine car drop, track, conveyor
15, up, 0. 3
16, special transformer, special switch, dedicated line
17, the wind, 10
18. The power supply line and coal mining face of the selective leakage protection device are separated.
19. Withdraw personnel and cut off the power supply
20, 10, 0, 5%
21, chicken paws, sheep tail, Ming joints
22, 3, 6
128
23, 0, 1,
24, casing, tight sealing pipe
25, overcurrent, grounding, leakage
26, electric motor, coal electric drill (lighting)
27, short circuit, overload, single phase disconnection
28, product certification, explosion-proof certificate, coal mine product safety signs
29, leak detection, leakage lockout, short circuit, overload, phase failure
30, 0, 1
31, 15 ,
32. Bucket operation section
33, cut off the power supply, clutch
34, stop using the electric drill to drill
35, stop working, cut off the power, evacuate personnel, handle
36, 1,0%
37, 1, 0%, 1, 5%, manual
38. Wind power and methane power-off instrument
39. Methane wind power, methane power-off instrument and wind power lockout
40, pedestrians do not drive, driving is not pedestrian
41, armor, plastic, mining rubber
42. Economic current method, long-term load current
43, EX,
44, explosion-proof, explosion-proof
45, prohibited use, long-term storage
46, rated, allowed overcurrent time
47, short circuit; overload, grounding, undervoltage release
48, short circuit, overload, leakage
49, short circuit, overload, single phase disconnection, leakage lock
50. Mining substation, mining area distribution point, auxiliary grounding bus
51, refused to move, mistake
129
Selectivity, rapidity, sensitivity, operational reliability, undervoltage protection, overvoltage protection, explosion-proof, explosion-proof
1, 0%
Non-on-duty electrical personnel vacuum electromagnetic detonators,
Wear insulated gloves and wear electrician insulated boots.
1, BCFG, ADE, 2, B, 3, AB, 4, B, 5, B, 6, BC,
7, BC, 8, B, 9, B, 10, B, 11, C, 12, AB, 13,
BC, 14, BC, 15, B, 16, C, 17, B, 18, B, 19, B,
20, CB, 21, C, 22, A, 23, AC, 24, C, 25, C,
26, B, 27, B, 28, A, 29, B, 30, B
Third, the judgment question:
1, √, 2, X, 3, √, 4, X, 5, √, 6, X, 7, √, 8,
X, 9, X, 10, √, 11, X, 12, √, 13, √, 14, X,
15, X, 16, √, 17, X, 18, X, 19, √, 20, √, 21,
X,22, X,23, √,24, X,25, X,26, X,27, √,
28, √, 29, √, 30, X, 31, X, 32, √, 33, √, 34,
X, 35, √, 36, √, 37, X, 38, √, 39, √, 40, √,
41, √, 42, X, 43, √, 44, √, 45, √, 46, √, 47,
√, 48, √, 49, X, 50, X.
Fourth, the question and answer questions
1. Answer: When selecting the cable cross section, the following four principles should be observed:
(1) When the cable is in normal operation, the temperature rises.
(2) Select according to the allowable voltage loss when the cable line I is used.
(3) The cable cross section should be selected to meet the mechanical strength requirements.
(4) The minimum two-phase short-circuit current at the end of the cable should be greater than the set current value of the feed switch.
2. Answers: The “Safety Regulations for Coal Mines” stipulates that: “Gas spouting area, high gas mine, coal (rock) and gas (carbon dioxide) protruding in the mine, the local ventilator of the excavation working face shall adopt three special (special transformer, special Switch, special line) power supply; power supply line with selective leakage protection device can also be used, but every day should be checked by a special person to ensure reliable operation of the local fan.” The local ventilators of the two adjacent roadways can be powered by a set of “three special” equipment, or they can be powered by two sets of low-voltage lines. However, a local ventilator must not supply air to two heading faces.
3, A: Note:
(1) The speed of the measuring time meter should be kept at 120r/rain or constant.
(2) When the three terminals of the megohmmeter lead out of the line, do not entangle each other, it is best to use a single strand.
(3) The megohmmeter voltage should be compatible with the voltage level of the device under test.
(4) When measuring equipment with large capacitance, such as large motor or long cable insulation, the initial charging current is large, and the indication value of the shaking table pointer is small, but this does not mean that the equipment under test is poorly insulated. It must be after a certain period of time, and the reading can be accurate after the pointer is stable.
4. A: In order to facilitate the management of the non-flame retarding performance of the mine rubber sheathed flexible cable, it is usually possible to make a reference discrimination on the ground for the non-flammability of the rubber sheath. The method is as follows:
(1) Using an electrician knife at the end of the cable to be tested, but with a length of 200 mm, a width of 10 mm, and a thickness of 2 soils of 0,3 mm, the end of the cable is clamped with an electrician's pliers, and the narrow side is downward;
(2) Burning with an alcohol lamp or an alcohol-burning lamp with a flame height of not less than 50 mm
131
52, ia, ib, ib
53, 0, 1, 50
54. Selectivity, rapidity, sensitivity, and operational reliability
55, under voltage protection, over voltage protection
56, explosion-proof, explosion-proof
57, 1, 0%
58. Non-duty electrical personnel
59. Vacuum electromagnetic detonator
60, wear insulated gloves, wear electrician insulated boots, two, multiple choice questions:
1, BCFG, ADE, 2, B, 3, AB, 4, B, 5, B, 6, BC,
7, BC, 8, B, 9, B, 10, B, 11, C, 12, AB, 13,
BC, 14, BC, 15, B, 16, C, 17, B, 18, B, 19, B,
20, CB, 21, C, 22, A, 23, AC, 24, C, 25, C,
26, B, 27, B, 28, A, 29, B, 30, B
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