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401. What are the technical measures for safe work on electrical equipment? Answer: Power outage, voltage testing, grounding, installation of warning signs, and setting up barriers. 402. Workers must take an exam on electrical safety procedures once a year; those who have been away from electrical work for several months or more due to certain reasons should relearn these procedures Answer: For those over 3 months, it is 403. The moisture content in coal is high; what is the impact on the coal transportation system in winter? Answer: The coal freezes, causing the belt to slip; in severe cases, the belt tears. 404. What is the spontaneous combustion of coal? Answer: When coal oxidizes in air, the heat generated cannot dissipate in all directions and instead accumulates within the pile of coal. As a result, the temperature inside the pile rises continuously until it reaches the ignition point, causing the coal to burn on its own – this phenomenon is known as spontaneous combustion of coal. 405. What does the principle of “three no-lets-go” regarding accidents refer to? Answer: Do not let go until the cause of the accident is clear ； Those responsible for the accident, as well as the general public who lack education, will not be spared ； No risk is overlooked without preventive measures. 406. What should be done if someone is electrocuted? Answer: Turn off the power supply, remove the person who has been electrocuted from the source of electricity, and provide first aid. 407. How to carry out effective flood control, disaster prevention, and moisture protection work in the field of thermal power operation? Answer: 1) Periodically test-operate the sewage pump ； 2) Remove standing water promptly ； 3) Turn on the moisture-proof light inside the electrical cabinet ； 4) Close doors and windows ； 5) Prevent the loss and collapse of coal. 6) Operations of the bucket wheel conveyor should be halted in case of strong winds or heavy rain, and the conveyor should be stopped on the wind-sheltered slope at the southern end of the coal yard ； 7) Ensure that there is always coal stored in the dry coal shed, so that dry coal can be supplied to the silos during prolonged rainy periods. 408. Into which grades is light diesel classified according to its freezing point? Which one does our factory use? Answer: Light diesel is classified into five grades based on freezing point: 0, +20, -10, -20, and -35. Our factory produces #0 light diesel. 409. What are the conditions under which oil tanks need to be heated with steam in winter? Answer: Turn on the steam when the temperature is below 3 degrees, and turn it off when it is above 10 degrees. 410. What are the requirements for using industrial cooling water? Answer: Appropriate amount, unobstructed flow, continuous. 411. What is the temperature at which cooling sprays need to be activated in oil tanks during summer? Answer: 45 degrees, 412. What are the methods to reduce the temperature of a coal pile? Answer: Turning over the pile, loosening the pile, and applying large amounts of water. 413. What are the specific requirements for the “four no’s” in oil areas? Answer: No oil residue, no open flames, no flammable materials, and no weeds. 414. For thermal power plants that do not use a single type of coal, what preparations should be made before the coal is fed into the furnace? Answer: Coal blending work. 415. What should be done in the event of a fire involving electrical equipment? Answer: Immediately cut off the power to the relevant equipment, and then extinguish the fire. 416. What devices should be installed at all key working locations of the coal conveyor belt? Answer: Pull-cord switch and alarm bell. 417. What precautions should be taken in the coal conveying system when the volatiles and sulfur content of the coal in use increase? Answer: Explosion-proof work. 418. By how much does the calorific value of bituminous coal decrease after being stored for 1 year? Answer: 1%-10% 419. What interlock relationships exist in the car dumper system’s equipment? Answer? 1. Interlock between the boom of the vehicle dispatching machine and the sampler ； 2. Interlock between the vehicle controller and the main unit ； 3. Interlock between the vehicle pulling machine and the vehicle transfer platform ； 4. Interlock between the workbench and the trolley machine ； 5. Interlock between the vehicle transfer platform and the boom of the vehicle steering machine. 420. What are the characteristics of the traveling mechanism of stackers-reclaimers? Answer: The traveling mechanism consists of two sets of driven trolleys and a driving trolley. The drive trolley is equipped with a two-speed motor; when not engaged in stacking or picking operations, the speed of the bucket wheel stacker-reclaimer when moving empty is up to 30 m/min, while its speed during such operations is 7 m/min. 421. What are the characteristics of the bucket wheel in a bucket wheel stacker-reclaimer? Answer: The bucket wheel adopts a semi-format structure, and such a bucket wheel operates smoothly, with high efficiency and excellent unloading performance in coal yard operations. The edges of the bucket wheel are welded with wear-resistant teeth, which enable coal extraction from frozen layers with a thickness of no more than 100 mm during winter. 422. What is the main function of the bucket wheel luffing mechanism? Answer: The luffing mechanism of the bucket wheel conveyor is primarily used to enable the pitching motion of the cantilever, thereby adjusting the picking height of the bucket wheel during material picking and the drop height of the material during stacking. 423. How to reduce vibration during the operation of a bucket wheel conveyor? Answer: 1) When the bucket wheel conveyor is used for rapid material handling, the switching between fast and slow speeds can cause severe vibrations; the travel control should be set to zero directly, and material handling should be carried out at a slow speed after the machine has come to a stop. 2) When the bucket wheel conveyor is taking material, if the coal is hard it can cause mild vibration; in such cases, the method of taking more material in smaller amounts or less material in larger amounts can be adopted depending on the actual situation, to avoid vibration. 3) When extracting material, if the bucket digs up to the ground level, it will cause significant vibration and may damage the bucket; therefore, it is necessary to ensure proper supervision and control the extraction depth, keeping it at least 0.5 meters above the ground surface. 4) When large rocks, wooden pieces, and other debris are found, they should be removed first before coal can be taken. 5) It is prohibited to take hard coal that has been compacted by vehicles. 424. Precautions when the conveyor belt crane’s 380V cable reel does not rotate: Answer: 1) Stop the equipment immediately and contact maintenance personnel to handle it ； 2) Strengthen the monitoring of the bucket wheel crane cable reel while it remains in operation ； 3) When the vehicle moves in the direction of reeling in the cable, close supervision of the cable reel is necessary. It is advisable to move at a low speed; when traveling over long distances, the speed should be changed gradually to prevent the cable from scattering due to inertial sliding at high speed with the engine in neutral. 4) When the overhead crane starts moving in the direction of cable deployment, it is advisable to begin moving at a low speed, in order to avoid the 380V cable reel getting stuck due to high-speed movement, which could result in the cable breaking. 425. Briefly describe the advantages and disadvantages of rotary tipplers? Answer: Advantages: high unloading efficiency, low power consumption, large rotation angle ； Disadvantages: A large amount of earthwork is required; the foundation depth reaches 13 meters. 426. Briefly describe the structure of the car dumper body? Answer: Rotor, clamping device, backing plate assembly, idler roller device, vibrator, end stop, material guiding device, transmission device, hydraulic system. 427. Concrete weights are installed in the front beam on the rotor of the car dumper – what is their purpose? Answer: Balance the load on the rotor, thereby reducing the unbalanced torque, lowering the driving power, and reducing the flipping impact. 428. What are the reasons for inaccurate alignment of the car dumper platform? Answer: 1. Coal accumulation at the support seat end. 2. Brake failure. 3. Pinion seat displacement. 4. The travel switch disconnects prematurely. 5. Eddy currents are abnormal. 6. Fault in the main control controller. 429. What are the advantages and disadvantages of the three stacking methods used by bucket wheel stackers? Answer: Material piling operations include three methods: rotary piling, fixed-point piling, and traveling piling. The rotary stacking method involves the bucket wheel conveyor stopping at a certain point on the track, with its rotating arm being used to throw coal onto the coal pile. The advantage of this method is that the coal pile has a neat shape, resulting in a high utilization rate of the coal yard. The downside is that the rotation keeps working, which is not economical. The fixed-point stacking method involves keeping the elevation and horizontal angles of the boom constant while the bucket wheel conveyor stacks the material. Once the coal pile reaches a certain height, either the front arm is rotated by a certain angle, or the front arm remains stationary while the main frame moves a certain distance. The advantage of this method is: it requires few actions and is relatively economical. The downside is ； The shape of the coal pile is irregular, and the utilization coefficient of the coal yard is low. The walking stacking method involves setting the front arm of the bucket wheel loader at a certain angle and height, then moving the loader while stacking coal; once it reaches the end of the coal storage area, it moves back and continues stacking, with the front arm rotating by a certain angle at the same time. The disadvantage of this method is that the walking motor is always in operation, which is inefficient, and the machine experiences significant vibration. 430. After the maintenance is complete and the equipment is tested, is it allowed to unlock manual start/stop? Answer: For 431, how many positions are there for the coal blending control lever? Which ones are they respectively? Answer: 3. Programmed setting, manual setting, zero position 432. How does the control room control the on-site coal plow? Answer: 1. The coal plow is at the programmed position ； 2. Which control handle for coal blending should be selected? 433. Which controller and which bin corresponds to Burner & Operation #12 bin? Answer: When unloading at #3 Unit, Bin B, location 434, to the #B bucket wheel conveyor, which equipment along the line must be started manually on-site? Answer: For the 7PB disc type magnetizer 435, during unloading operations, what is the interlock relationship between the tipper and the bucket wheel conveyor with the equipment along the line? Answer: The bucket wheel conveyor is involved in the interlock system, while the dump car is not. What are the two startup methods for belts 436 and #7? Answer: How should it be started during material retrieval operation? Forward start, reverse start. Forward start 437: During normal operation, is it allowed to perform lamp testing from the control room console? Answer: 438 is not allowed. Is it permissible to use the emergency stop button during normal shutdown? Answer: When 439 is not allowed and the machine is in operation, if the emergency stop button is pressed, which device will not shut down immediately? Answer: For the coal crusher 440, when the optical indicator in the control room sends a \"slight deviation\" signal, will the equipment trip? Will tripping occur if a “re-run deviation” signal is sent? Answer: No. It will be a short-answer question 441: What are the three methods of coal blending? Answer: For low coal levels, priority allocation, sequential allocation, and allocation of the remaining coal are used. The #B bucket elevator transports coal from the B side to bin 6PB. How can the control room carry out interlocked manual startup operations? Answer: A. Set the control mode selector lever to the interlock manual position ； B. Press the selection buttons for Bucket 2 pickup, C21, C23, and C28; the indicator light \"Process Valid\" will turn on ； C. Press the “Pre-start” button, and the “Start Allowed” indicator light will turn on ； D. Start the equipment along the line in reverse coal flow order. 443. What are the principles for starting and stopping equipment along the coal transport route? Answer: Start against the coal flow, stop with the coal flow. 444. #Bucket wheel conveyor from Side B to the upper bin of 6PB: How to operate the pull rope at 6PB, and which devices will trip as a result? Answer: GZSB, DMF4, 3PB, 7PB, and DLJ2 trip immediately, while SMB shuts down after a delay. 445. How to disable the interlock between the 6PB belt and the 5PB belt? Answer: A. Enter the host computer’s “Function Selection”” ； B. Press “F3” and select “6PB local”” ； C. Press the “ALT+M” button. 446. What are the various operation modes of program control? Answer: 6 types, loading onto the dump truck, loading onto #A bucket wheel conveyor, loading onto #B bucket wheel conveyor, unloading from the dump truck onto #A bucket wheel conveyor, unloading from the dump truck onto #B bucket wheel conveyor, and coal transfer. 447. Is L7PB involved in the interlock when unloading from Side B into Bucket B? What are the harms? Answer: It does not participate in interlocking; if L7PB is in the lowered position, it will cause coal blockage at the heads of 7PB and 2PB. 448. What is the most important task that the combustion and operation team must carry out to ensure the stable and safe operation of the centralized control system? Answer: Coal allocation by storage area. 449. What is the significance of achieving centralized control for combustion operation? Answer: A. Improve labor productivity ； B. Reduce labor intensity ； C. Improve the working environment ； D. Improve the safety and reliability of equipment operation. 450. Briefly describe the power-on process of the PLC in the control room? Answer: A. Supply power to the remote station ； B. Supply power to the power cabinet in the control room ； C. Supply power to the communication module. 451. What should be done in case of a fire involving electrical equipment? Answer: The power supply to the relevant equipment should be cut off immediately, followed by extinguishing the fire. 452. What voltage of electrical tools must be used when working inside metal containers? Answer: Below 24V. 453. What type of fire extinguisher should be used to extinguish fires involving potentially live electrical equipment, as well as generators and motors? Answer: Dry chemical fire extinguishers, carbon dioxide fire extinguishers, or 1211 fire extinguishers. 454. What are the main protective devices for electric motors? Answer: Interphase protection, single-phase ground protection, overload protection, low voltage protection. 455. Under what circumstances should the motor be shut down in case of an accident? Answer: 1. In the event of a personal accident that requires the immediate shutdown of the motor ； 2. The machinery driven by the motor is damaged to a dangerous level ； 3. The motor is on fire and smoking. 456. What should be done if someone is electrocuted? Answer: When someone is found to be electrocuted, the power supply should be turned off immediately to disconnect the victim from the electricity source, and first aid should be provided. When working at heights, care must be taken to prevent falls from great heights during rescue operations. 457. What are the common faults of electric motors? Answer: Motor vibration, motor overheating, motor operating on two phases, increased motor temperature, vibration, humming, etc. 458. What are the continuous magnetic strength levels of belt-type iron removers? Answer: 100% and 25% – these are the two options for 459. What type of coal crusher does our factory use? Answer: Ring coal crusher 460. What are the two operating modes of the belt-type magnetic separator? Answer: What type is the belt tensioning device for #8 in our plant, for normal operation and forced operation modes 461? Answer: The trolley tensioning device is 462. What is the rotational speed of the coal conveyor belt in our factory? Answer: 2.5 M/S463. What are the three common types of coal conveyor belt tensioning devices? Answer: Screw, trolley, weight 464. What are the two types of buffer idlers in a belt conveyor? Answer: Rubber, spring 465. What determines the width of a belt conveyor? Answer: Transport volume and speed 466. What is the principle of operation of a belt conveyor? Answer: Principle of friction drive 467. What are the main components of a belt conveyor? Answer: Tape, upper and lower idlers, drum, tensioning device, motor, reducer, and protection devices. 468. What is the inclination angle of belt #4 in our factory? Answer: 16 degrees 469. Generally, what is the maximum inclination allowed for coal conveyor belts at the horizontal level? Answer: 18 degrees, 470. Parallel idlers are generally long idlers; what is their main purpose? Answer: Lower idler 471. What is the allowable temperature for the reducer’s operating environment? Answer: -40 degrees to 45 degrees. 472. What is the maximum allowable deviation of the conveyor belt during operation? Answer: Idler rollers and the edges of the drums 473. At what angle above a certain degree should a braking device be installed on a belt conveyor? Answer: 4 degrees, 474. After the coal crusher is started, the mechanical part struggles to rotate or does not rotate at all, and the current remains high without dropping back – what is the reason? Answer: There are debris in the machine, and coal has blocked chamber 475 of the coal crusher. Why is the current of the coal crusher fluctuating? Answer: Uneven feeding 476. What are the reasons for severe vibration of the coal crusher, a sudden increase in current, and loud noises? Answer: Large pieces of coal or iron enter the coal crusher 477. What are the different types of iron removers? Answer: Suspended, drum type, belt type 478. What is the maximum allowable temperature for the bearings of the operating equipment? Answer: 65 degrees, 479. What is the maximum allowable temperature for the reducer of the operating equipment? Answer: 60 degrees, 480. What is the maximum allowable temperature for the motor of the operating equipment? Answer: 80 degrees, 481. The belt stops operating under full load; once the motor has cooled down, how many times is it allowed to start while under load? Answer: 2 times, 482. What is the interval required between consecutive starts of the belt? Answer: 5 minutes and 483. The belt failed to start under load 2 times – what should be done? Answer: Reduce the load on the belt, and restart the motor after it has cooled down. 484. Under what circumstances should the coal distributor and the three-way dampers be switched during operation? Answer: No load, no sticky coal, 485. What changes in the coal crusher should be monitored while it is in operation? Answer: Ammeter 486. What should be the maximum bearing temperature when the coal crusher is in operation? Answer: 75 degrees, 487. What should be the maximum allowable vibration of the machine body when the coal crusher is in operation? Answer: 0.15MM488. What should be the vibration level of the motor driving the coal crusher? Answer: 0.1MM489. What are the seven protections for belt conveyors? Answer: Polar deviation, coal flow signal, slip protection, speed switch, two-way emergency pull cord switch, coal blockage signal, longitudinal tear protection. 490. What is the output capacity of the roller screen in our factory? Answer: 1500T/H491. What is the particle size of the undersize material from our factory’s roller screen? Answer: ≤40MM492. Why is an interlock device required in the coal conveyor belt system? Answer: 1. To reduce the number of starts and stops of the system conveyor ； 2. Ensure that the coal conveyors in the system start and stop in sequence ； 3. When a critical device in the system fails, the system stops automatically. 493. What are the common reasons for belt deviation when the coal conveying belt is in operation? Answer: 1. Coal sticking to the drum ； 2. The tape connection is not proper ； 3. The coal dropping pipe does not drop coal properly ； 4. The guide chute is too tight or misaligned. 494. What is the impact of dust on coal conveying equipment? Answer: 1. Dust adheres to the equipment’s casing, preventing it from dissipating heat and reducing its service life ； 2. Dust adheres to electrical connections, causing electrical faults ； 3. Dust adheres to the rotating parts, affecting bearing lubrication. 495. Why is it generally not allowed to start a belt conveyor under heavy load? Answer: This is because during no-load startup, especially in inclined conveyors, the instantaneous current required for startup **exceeds several times the current limit allowed by the motor. If startup occurs under heavy load, the motor may overheat and get damaged; therefore, it is not permitted to start the conveyor under heavy load under normal circumstances. 496. What is the reason why the motor does not rotate when a belt conveyor starts operating? Answer: 1. No power supply ； 2. Insurance fuse blown ； 3. The control device is faulty. 497. What are the advantages and disadvantages of roller screens? Answer: Advantages: simple structure, stable operation, reliable performance, screening efficiency of 80%, low maintenance requirements, and easy installation ； Disadvantages: Excessive moisture can cause coal blockage, it makes a lot of noise during operation, and its production capacity is low. 498. What is the working principle of a ring coal crusher? Answer: A high-speed rotating rotor is used to drive the hammer to impact and crush the material; the impacted material is then subjected to compression, shearing, and grinding actions between the hammer, the crushing plate, and the screening plate, thereby achieving the desired particle size. 499. What are the high calorific value and low calorific value of coal? Answer: The heat released when 1 kg of coal burns completely, with the water in the combustion products remaining in liquid form, is known as the high calorific value. The calorific value when the water in the combustion products remains in a vapor state is the lower calorific value. 500. What is the impact of increased moisture content in coal on the coal transportation system? Answer: 1) Excessive moisture in coal can cause coal to stick to and clog the equipment used for transporting it; in severe cases, this can halt the coal supply. 2) High moisture content in coal leads to gravity flow during transportation, which makes it difficult to feed coal into the systems. In extremely cold winters, especially in the north, the coal can freeze, thereby affecting its unloading and feeding. 3) An increase in moisture content reduces the lower heating value of coal.