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1. Multiple choice questions 1. In order to accurately reflect the shape and size of an object, it is often necessary to use (3) views to represent it. 2. The heat added to heat saturated water to dry saturated steam is called (heat of vaporization) 3. In order to express the internal shape of the machine parts, (section view) is generally used. 4. (Steam turbine) is one of the three main equipment of thermal power plants. Its task is to convert the thermal energy of steam into the mechanical energy of rotor rotation. 5. The calorific value of standard coal is (29310) KJ/Kg. 6. The voltage at both ends of the light bulb when four light bulbs (220V, 100W) are connected in series on a 220V power supply circuit is the minimum. 7. At a certain temperature, the resistance of the conductor is (proportional to the length of the conductor) 8. The law that determines that the heat generated when the current passes through the conductor is proportional to the square of the current, the resistance of the conductor and the passing time is (Joule-Lenz law) Nephew 9. The main reason for the low efficiency of thermal power plants is (the exhaust heat loss of the steam turbine is large) 10. In engineering thermodynamics, the basic state parameters of the working fluid are pressure, temperature and (specific volume) 11. The relationship between absolute pressure and gauge pressure is (P absolute = P gauge + Pamb) 12. The drawing scale of 1:20 means that the actual length of the machine part with a drawing size of 20 mm is (400) mm 13. The non-verticality of the anchor bolts in the installation of boiler auxiliary machinery shall not be greater than (1/100) k of its length. 14. When drawing a symmetry line on a circular axis, the line should usually be drawn on the (V-shaped iron) 15. Use a steel ruler to measure the workpiece. When reading, the line of sight must be (perpendicular to) the surface of the steel ruler. 16. (Air blower) is used to ensure the amount of air required for supplying the boiler for combustion. 17. In large thermal power plants, the motor voltage of water supply pumps, induced draft fans, blowers, primary fans, ball mills, circulating water pumps, etc. is mostly (6000). 18. The angle between the two slopes of the B-type V-belt (40°) 19. The (axial clearance) of the sliding bearing can be adjusted by adjusting the screw of the thrust pad or turning the thrust surface. 20. The ability of a metal material to resist deformation and damage under the action of external forces is called (strength) 21. The working principle of the (fan mill) coal mill is: after the raw coal is brought into the coal mill by hot air, the impeller rotates at high speed to hit the coal, completing the grinding process. 22. Steel is divided into ordinary steel, high-quality steel and high-grade high-quality steel according to {quality (sulfur and phosphorus content)}. 23. For the timing of the fan coupling, use a dial indicator to measure the outer circle of the coupling. The readings of the dial indicator at symmetrical positions are different (the outer circles of the two couplings are not concentric). 24. Chain transmission relies on the (meshing) of the chain and the sprocket to transmit power. 25. Bolt connections are mainly used when the connected parts (which are not too thick) can be assembled from both sides of the connecting parts. 26. The threaded hole on the top of the sliding bearing is used for mounting (oil cup). 27. The efficiency of gear transmission can reach (0.98-0.99) 28. Alloy refers to a substance composed of one main (metal element) and another or several metal or non-metal elements. 29. The electrical conductivity and thermal conductivity of alloy are (lower than) that of pure metal. 30. If you need steel with high plasticity and toughness, choose (low carbon steel) 31. When measuring the thickness of the workpiece, you can use an outer diameter micrometer, and its maximum measurement range is (900-1000) mm 32. Making shrimp waist requires the following known conditions (bending radius, pipe diameter, bending angle, number of short pipe sections) 2. Short answer questions: 1. What is the essence of the first law of thermodynamics? Answer: The essence of the first law of thermodynamics is the law of energy conversion and conservation. It tells us that different forms of energy can be converted into each other, but the total amount before and after conversion remains unchanged. 2. What are the three elements for marking dimensions when drawing? Answer: A complete dimension should include three elements: dimension lines, dimension lines and dimension numbers. 3. What are the assembly dimensions of the assembly drawing? Answer: Including matching dimensions, connection dimensions, mutual position dimensions, and dimensions that need to be processed during assembly. 4. What is a saw path? What is the function of a saw path? Answer: A saw path is that all the saw teeth on the saw blade are staggered left and right according to a certain rule and arranged into a certain shape. The function of the saw path is to increase the width of the saw kerf during sawing, reduce the frictional resistance of the saw kerf to the saw blade, and prevent the saw from being pinched. 5. What is the projection rule between the three views in mechanical drawing? Answer: The projection rule of the three views is: the length of the main and top views are aligned. ； Main and left views are at the same height ； The widths of the top and left views are equal 6. What is scribing? What are the types of scribing? Answer: The operation of accurately drawing the processing boundary on the surface of the workpiece according to the size of the drawing or the actual object is called scribing. The scribing is divided into plane scribing and three-dimensional scribing 7. What does the main and auxiliary equipment of a thermal power plant include? answer: The equipment of thermal power plants mainly includes: Boilers, steam turbines, generators, etc. The auxiliary equipment mainly includes: feed water pump, circulating water pump, condensate water pump, air supply fan, induced draft fan, coal mill, primary air fan (powder discharge machine), forced circulation pump, condenser, transformer, heater, etc. 8. What is filing? What are the types of files? Answer: The operation of using a file to cut the surface of a workpiece to achieve the required size, shape, position and surface roughness is called filing. Files are generally divided into three categories: ordinary files, shaping files, and special files. 9. What is a cross-section view? Answer: Imagine cutting the machine part with a cross-section plane, removing the part between the observer and the cross-section plane, and projecting the remaining part to the projection plane, which is called a cross-sectional view. 10. What is drilling? What drilling machines are commonly used by fitters? Answer: The operation of using a drill to make a hole in the physical part of the workpiece is called drilling. Drilling machines commonly used by fitters include bench drills, vertical drills, radial drills and hand drills. 11. What is the function of scraping? Answer: 1. Scraping has the effect of pushing and calendering the workpiece surface. 2. The scraped surface forms relatively uniform shallow pits. These pits can store oil and reduce friction on the mating surface. 3. The scraped patterns can increase the beauty of the workpiece surface. 12. After the boiler overhaul, which auxiliary machines are the acceptance items after the whole plant overhaul? Answer: The following auxiliary machines are the acceptance items after the overhaul of the whole plant: blower, induced draft fan, pulverizer, coal mill, pulverizer, coal feeder, air preheater, etc. 13. What are the common types of blanking for boiler maintenance? Answer: Right pyramid cutting, round sky cutting, shrimp waist cutting, pulverized coal distributor cutting, etc. 14. What are the commonly used cutting methods for boiler maintenance? Answer: Commonly used blanking methods for boiler maintenance include: radiation method, trigonometric method and entropy calculation method 15. What role does the transformer play in the power system? Answer: The transformer plays an important role in the power system. It increases the voltage of the generator and transmits electrical energy to long distances through transmission lines, reducing losses, and then reduce the high voltage and distribute it to users to ensure the safety of electricity. Generally, from the power plant to the user, according to different requirements, the voltage needs to be converted multiple times, which is accomplished by transformers. 16. What does the coal mill model "DTM380/720" mean? Answer TM means that the type of coal mill is a low-speed cylindrical coal mill. ； 380 means that the effective length of the coal mill barrel is 3800mm; 720 means that the effective length of the coal mill barrel is 7200mm. 17. What are the main types of external sealing devices of centrifugal pumps? answer: There are mainly packing seals, mechanical seals, labyrinth seals, and floating ring seals. 18. What are the main characteristic curves of fans? Answer: 1. Flow rate and total pressure curve 2. Flow rate and power curve 3. Flow rate and efficiency curve 4. Flow rate and static pressure curve 5. Flow rate and net efficiency curve 19. What types of coal mills can be divided according to the working speed? Answer: Coal mills can generally be divided into three categories according to the working speed: 1. Low-speed grinding, such as steel ball mills 2. Medium-speed grinding, such as flat disc coal grinding Machine, bowl coal mill, E-type coal mill, MPS coal mill 3. High-speed coal mill, such as fan coal mill 20. What are the main components of an impeller pulverizer? Answer: An impeller pulverizer mainly consists of a shaft, upper impeller, lower impeller, scraper, reducer, casing, upper orifice plate, lower orifice plate, etc. 21. What are the commonly used boiler coal feeders? Answer: Commonly used boiler coal feeders mainly include: electromagnetic vibration coal feeder, belt coal feeder, scraper coal feeder and disc coal feeder, etc. 22. What is the function of the screw pulverizer in the pulverizing system? Answer: In the storage-type pulverizing system, the screw pulverizer can transfer the pulverized coal separated by the fine powder separator to the pulverized coal bins of other boilers to realize the distribution of pulverized coal between pulverized coal bins and achieve the purpose of not having to shut down the furnace after stopping the pulverizing system of this furnace. 23. What is quenching and tempering treatment? What is its purpose? Answer: The heat treatment method of subjecting quenched steel parts to high temperature tempering is called quenching and tempering treatment. Purpose: 1. To refine the structure; 2. To obtain good comprehensive mechanical properties. 24. What is the meaning of the HG-670/13.7-540/540-8 boiler model? Answer: It represents the 8th modification design of a boiler produced by Harbin Boiler Factory, with a boiler capacity of 670t/h, a steam pressure of 13.7Mpa (gauge pressure), a temperature of 540°C, and a steam temperature of 540°C. 25. What is the function of the sealing device of the rotary air preheater? Answer: When the rotary air preheater is running, there is a certain gap between movement and static, and there is a pressure difference between the air and the flue gas, which will cause air to leak into the flue gas. The function of the sealing device is to prevent and reduce air leakage 26. Intermediate silo-type powder milling What equipment does the system include? Answer: The main equipment of the intermediate storage silo pulverizing system are: coal feeder, coal mill, coarse powder separator, fine powder separator, pulverized coal bin, powder feeder, powder exhaust fan, screw powder conveyor, etc. 27. What quantities are commonly used for boiler maintenance? Answer: Large and small steel rulers, steel tapes, vernier calipers, micrometers, dial indicators, feeler gauges, depth gauges, levels, speed meters, vibration meters, etc. 28. Which types of frame level instruments can be divided according to the length of their working surfaces? Answer: They can be divided into 4 types: 100mm, 150mm, 200mm, 250mm 29. What wrenches are needed for the maintenance of boiler auxiliary machines? Answer: Commonly used wrenches include: adjustable wrench, open fixed wrench, closed fixed wrench, plum blossom wrench, electric wrench, hydraulic wrench, pipe wrench, etc. 30. What parts does the pneumatic transmission device consist of? Answer: It mainly consists of the following four parts: 1. Air pressure generating device 2. Actuator 3. Control component 4. Auxiliary component 31. After equipment problems occur, what issues should be clarified before maintenance? Answer: If there is a problem with the equipment, the questions that should be clarified before maintenance are: 1. The cause of the damage 2. Is it an individual defect or a system defect 3. If the undiscovered defect causes further damage, will it endanger safety, that is, will it cause a personal accident or a larger equipment accident? 32. What is the allowable deviation (axial, radial) of the elastic coupling wheel alignment? Answer: The alignment deviation should be determined according to the rotation speed of the rotating machine. When the rotation speed is 750r/min, it shall not exceed 0.10mm; when the rotation speed is 1500r/min, it shall not exceed 0.08mm; when the rotation speed is 3000r/min, it shall not exceed 0.06mm. 33. What are elastic deformation and plastic deformation? Answer: The change in shape and volume of a component under the action of external forces is called deformation. When the external force is removed, the deformation of the component that can return to its original shape is called elastic deformation. When the external force is removed, the deformation of the component that cannot return to its original shape is called plastic deformation. 34. What are the disassembly requirements for rolling bearings? Answer: 1. The force application part must be accurate when disassembling. When removing the bearing from the shaft, force must be applied to the inner ring. When taking the bearing out of the bearing chamber, force must be applied to the outer ring. 2. The force should be applied as smoothly, evenly and slowly as possible. It is best to use a bearing puller. 35. What components does a vibrating coal feeder consist of? Answer: Generally it consists of five parts: coal hopper, electromagnetic vibrator, coal feeding trough, coal feeding pipe and shock absorber. 36. What are the main components of the axial flow fan? Answer: The axial flow fan mainly consists of the shell, bearing air inlet chamber, impeller, spindle, adjustment mechanism, sealing device, etc. 37. Briefly describe the function of the welding rod? Answer: Welding rods can be used as electrodes to conduct welding current, and as filler metal for welds and protective materials for welding pools. 38. What are the three elements of force? Answer: The three elements of force refer to: the size, direction and point of action of the force. 39. What are the three principles of not letting go when dealing with accidents? Answer: We should adhere to the three principles of not letting go when dealing with accidents, that is, if the cause of the accident is unclear, we will not let it go; if the person responsible for the accident and the general public are not educated, we will not let it go; if there are no preventive measures, we will not let it go. 40. What is manual arc welding? Answer: Manual arc welding is a process in which a hand-operated electric welder uses the heat of the arc between the welding rod and the weldment to achieve welding. 41. What are the main tools and equipment commonly used for lifting? Answer: Tools: hemp rope, steel wire rope, wire rope clamps, unloading clamps (clasps), lifting rings and horizontal suspension beams, ground anchor equipment: Jack, chain hoist, pulley and pulley block, winch 42. What are the most important basic tasks in total quality management work? Answer: The most important basic tasks in total quality management work are: quality education work, quality responsibility standardization work, measurement work, quality information work, etc. 43. How to use and insulate gloves correctly? Answer: Before using insulated gloves, you should check whether there are air leaks or cracks. When wearing gloves, you should put the cuffs of the coat into the extended part of the gloves. They must be wiped clean after use, put in a cabinet and placed separately from other tools. Tests are conducted every six months. Those that fail the test are prohibited from use. 44. What are the basic methods of fire prevention? Answer: The basic methods of fire prevention generally include: controlling combustibles, isolating air, eliminating ignition sources, and preventing the spread of fire and explosion waves. 45. What factors are related to the degree of injury from electric shock to the human body? Answer: The degree of injury from electric shock to the human body is related to six factors, including the size of the current, the level of the voltage, the resistance of the human body, the path of the current through the human body, the length of the electric shock time, and the mental state. 46. What are the basic contents of the welding process? Answer: The basic contents of the welding process include: pre-welding preparation, preheating, spot fixing, welding specification selection, welding methods, operating techniques, post-weld heat treatment and inspection 47. How many binding methods are there for lead wire buckles when erecting scaffolding? Answer: 1. Hand binding method (single-sided cross) 2. Oblique binding method (double-sided cross) 3. Slip-on binding method 48. What are the differences in use between multi-strand steel wire ropes and single-strand steel wire ropes? Answer: Multi-strand steel wire ropes are more flexible and can work on smaller diameter pulleys or drums. Single-strand steel wire ropes are more rigid and should not be flexed, requiring larger diameter pulleys or drums. 49. What measures can be taken to prevent electric shock accidents at construction sites? Answer: 1. Electric tools should be reliably grounded 2. Live equipment should have obvious signs 3. Set up electric shock safety devices 4. In some places where the risk of electric shock is high, use safe low-voltage current 5. After using electrical equipment and tools, cut off the power supply in time 50. How to grind valves with grinding sand or grinding paste Answer: Generally, it is carried out in the following three steps: 1. Rough grinding. Use a grinding head and grinding seat, first use coarse grinding sand to grind away the pits and small pits of the valve. 2. Medium grinding. Replace a new grinding head or grinding seat, and use relatively fine grinding sand for manual or mechanized grinding. 3. Fine grinding, use abrasive paste to grind the valve disc of the valve against the valve seat until it reaches the standard. 51. What are the main advantages of gear transmission? 58. What safety matters should be paid attention to when chiseling? Answer: When chiseling, you should pay attention to: 1. To prevent the hammer head from flying out and injuring people, the hammer head must be installed firmly, and the operator is not allowed to wear gloves; 2. Chiseling is not allowed against people, and the operator is best to wear protective glasses; 3. The hair on the tail of the chisel The thorns should be ground off at any time to avoid hurting the hands; 4. In order to prevent the chisel from slipping along the chisel cutting surface, the chisel should always be kept sharp and a reasonable back angle should be maintained. 59. What are the methods of starting the saw when sawing a workpiece? What are the key points of operation? Answer: There are two ways to start sawing: far starting sawing and near starting sawing. The key points of sawing starting operation are: short stroke, low pressure, slow speed, and correct starting angle. 60. What are the steps to mark the workpiece before drilling? Answer: 1. Draw the cross center line of the aperture; 2. Make a center punch hole; 3. Draw a circle according to the hole diameter and punch the punch hole; 4. Re-punch the center punch hole (enlarge it) to facilitate the centering of the drop drill. 61. What are the steps for reading part drawings? Answer: Follow the following steps during the reading process: 1. Look at the title bar; 2. View analysis; 3. Dimensional analysis; 4. Reading of technical requirements; 5. Summary. 62. Explain the uses of five commonly used simple measuring tools such as steel ruler, knife-edge ruler, square ruler, caliper, and feeler gauge? answer: 1. The steel ruler can directly measure the size of the object, and can also be used to detect the flatness of the rough workpiece surface and rough machined surface; 2. The knife-edge ruler can be used to measure the straightness and flatness of the workpiece, and must be used in conjunction with the feeler gauge; 3. The square ruler is used to measure the workpiece. The verticality of the inner and outer corners of the workpiece is often used in conjunction with a feeler gauge; 4. The caliper is used to measure the inner and outer dimensions of the workpiece; 5. The feeler gauge is used to measure the gap between the two joint surfaces. 63. When threading, what are the causes of too thin threads and how to prevent them? Answer: Reasons: 1. The die swings too much or the pitch diameter of the thread becomes smaller due to deflection, multiple corrections, or excessive cutting. ； 2. Still use the pressure plate to move after starting to cut; prevention methods: 1. The force of the swing die must be balanced; 2. Only rotation force is used to remove pressure when starting to cut. 64. What types of couplings are there? Answer: Couplings generally include steel couplings, flexible couplings and semi-flexible couplings. 65. What types of sealing devices are there for the heating surface rotary air preheater? Answer: There are three types of radial seals, circumferential seals and axial seals. 66. What are the heating temperature requirements when assembling rolling bearings? Answer: Place the bearing in oil and slowly heat it. The heating temperature is controlled at 80~100℃, and the maximum is not allowed to exceed 120℃. 67. There is a part that needs to be connected with M10 bolts. Please choose an appropriate wrench and tell how much force you use? Answer: A 200mm (8-inch) wrench should be used, and a force of 16kgf should be applied. 68. The spherical surface of the main bearing of the steel ball mill must have good and reliable lubrication. What lubricants are generally used for the spherical surface? Answer: Mainly include butter, engine oil, mixed grease of butter and molybdenum disulfide, lard mixed with mercury lubricant 69. What are the clearances between the moving and static parts of the centrifugal fan? answer: 1. The axial and radial clearance between the collector and the impeller; 2. The clearance between the rear disc of the impeller and the inner wall of the casing; 3. The radial clearance where the shaft penetrates the casing 70. Which stages can the test operation procedure of the steel ball coal mill be divided into? What is the main content of each stage? Answer: It can be divided into three stages: The first stage is the no-load test operation, which includes the empty operation of the motor, reduction gearbox and large tank. ； The second stage is heavy load test operation, which includes adding steel balls to the large tank and then testing it. ； The third stage is the hot air test operation, which includes the test operation of adding coal and pulverizing. 71. What are the two methods for checking the clearance of the sliding bearing bush? What is the scope of use of each? Answer: There are two methods for clearance inspection: the lead wire inspection method and the feeler gauge inspection method. The lead wire inspection can measure the radial top clearance. The feeler gauge inspection method can measure the radial side clearance, the radial top clearance of the integral sliding bearing and the axial clearance of the sliding bearing. 72. Briefly describe the method of disassembling the centrifugal fan impeller? Answer: Fix the impeller, install a special shaft puller, and use two baking handles to evenly bake the impeller hub. When the hub temperature reaches 150~200℃, turn the screw or nut on the special shaft puller and slowly pull out the impeller. 73. What equipment does the compressed air system mainly include? Answer: The main equipment of the compressed air system includes: air compressor, regeneration dryer, air compressor outlet air storage tank, system pipelines, safety devices and instruments, etc. 74. For a piece of equipment, what parts does a complete maintenance record include? Answer: The main content of the maintenance record includes: the name of the equipment and components, relevant technical indicators, measurement data, measuring instruments, measuring personnel and measurement date, etc. 75. What are the installation steps of the heating surface rotary air preheater? Answer: The installation steps generally include: 1. Lower beam installation; 2. Shell installation; 3. Rotor installation; 4. Upper beam installation; 5. Gap adjustment; 6. Transmission mechanism and heat transfer element installation. 76. When installing the shroud of the hot surface rotary air preheater, in order to ensure that the center line of the shroud pin hole coincides with the pointer or vertical tip of the special positioning tool, what adjustment method is usually used? Answer: Adjustment should be made by placing a wedge-shaped shim between the shroud and the short cylinder. Adjust the shim blocks with different thicknesses or grind the inner ring of the shroud to ensure that the center line of the shroud pin hole coincides with the pointer or the vertical tip of the line. 77. What are the technical requirements when tightening the set of bolts? Answer: You cannot overtighten at one time. You should tighten gradually in three or more times. A group of bolts should be operated by one person (or the last time is operated by one person). The tightening sequence should be programmed when tightening the group of bolts. 78. What method is usually used to eliminate the error of the frame level itself? Answer: The method to eliminate the error of the frame level instrument is: after measuring once, mark the position, turn it to 180°C and measure again. The average of the two measurements is the actual value. 79. What content does the equipment maintenance technical ledger generally include? Answer: The content of the equipment maintenance technical ledger is: equipment operating status, maintenance status records, equipment defects and elimination records, etc. 80. What are the common types of shaft seals? Answer: Common shaft seals include: 1. Felt type shaft seal; 2. Cup type shaft seal; 3. Oil groove type shaft seal; 4. Labyrinth type shaft seal; 5. Labyrinth-felt type shaft seal. 81. In view of the phenomenon that the wind hood of the rotary air preheater shakes with the wind fluctuation, what methods are often used for maintenance? Answer: The following methods are often used: Reinforce the windshield to increase rigidity, change the windshield bar frame from a suspension spring to a compression spring, and move the U-shaped sealing piece outward toward the smoke side so that both upper and lower sides of the sealing bar frame are in contact with the air to achieve self-balancing of the wind force. 82. What does the annual maintenance plan include? Answer: The contents of the annual maintenance plan are: unit project name, major overhaul projects, major special projects and reasons for inclusion in the plan, main technical measures, maintenance progress plan, working hours and costs, etc. 83. What are the main factors causing bearing overtemperature? Answer: The main factors causing bearing overtemperature are: 1. Lack of oil or excess oil; 2. Oil quality deterioration; 3. Oil supply temperature is too high; 4. Improper assembly clearance; 5. Equipment vibration 84. What are the disassembly methods after threaded connectors are rusted? Answer: 1. Use a flat chisel to remove the nut; 2. Use a hacksaw to cut the nut tangentially along the external thread, and then remove it; 3. Use a counter-thread tap to remove the broken bolt. 4. Weld the hexagonal nut to remove 85. What are the inspection items for inspection of tungsten tiles? Answer: The inspection items are: 1. Clean the tile surface with kerosene or gasoline, and check whether the tungsten tile has cracks, blisters, or burns. ； 2. Check whether there are any scars on the journal; 3. Use red red powder to check the contact surface and contact points between the bearing bush and the journal; 4. Check whether there is enough clearance in the oil inlet groove to ensure smooth oil inflow; 5. Check the top clearance and side clearance of the tile to make them within the qualified range; 6. Use the oil leakage test method to check whether the tungsten tile has shelled out. 86. What are the contents of checking the ball bearing? Answer: The contents of inspecting ball bearings include: inspecting the balls and inner and outer rings for defects such as cracks, peeling, and spots, and checking the degree of wear ； Check the cooperation between the outer ring of the ball bearing and the bearing seat, the inner ring and the journal. 87. What is the meaning of 6×61+1 for the steel wire rope? Answer: 6 means 6 strands, 61 means 61 filaments per share, and 1 means 1 oil-impregnated linen or cotton yarn core. 88. What categories can valves be divided into according to their uses? Answer: Valve press 89. What are the commonly used forms of welded joints? Answer: Commonly used welded joints include butt joints, T-shaped joints, corner joints, and lap joints. 90. How to put out a motor fire? Answer: First, the power should be cut off quickly. When extinguishing the fire, prevent the shaft and bearings of the running motor from deforming. Use carbon dioxide or 1211 fire extinguishers when extinguishing the fire. You can also use steam to extinguish the fire. Do not use dry powder, sand, or soil to extinguish the fire. 91. What are basic safety appliances and auxiliary safety appliances? A: Basic safety appliances refer to those appliances with high insulation strength, which can withstand the working voltage of electrical equipment for a long time, and can be used directly to operate live equipment or contact live objects. Auxiliary safety appliances refer to those appliances whose insulation strength is not strong enough to withstand the working voltage of electrical equipment or lines, but can only enhance the protective effect of basic safety appliances. They are appliances used to prevent personal injuries such as contact voltage, step voltage, arc burns, etc. 92. What knots (buckles) are commonly used in maintenance work? Answer: Commonly used knots in maintenance work include: flat knot, combined knot, trapezoidal knot, double trapezoidal knot, post knot, figure 8 knot, inverted back knot, pipa knot, hook knot, bar knot, dead loop knot, puller knot, board head knot, and lap rope knot (button) 93. What is a weld symbol? What parts does a weld symbol consist of? Answer: The weld symbol is a kind of engineering language and is used to mark the weld form, weld size and welding method on the drawing. Weld symbols are the main basis for welding construction. Weld symbols generally consist of basic symbols and guide lines. If necessary, auxiliary symbols, supplementary symbols and weld size symbols can also be added? 94. What are the connection methods of pipelines and accessories? Answer: There are three connection methods of pipelines and accessories: welding connection, flange connection, screw connection 95. What protective equipment should a welder have? Answer: 1. Hand mask or hooded mask with filter; 2. Welding gloves; 3. Rubber insulating shoes; 4. White light glasses (protective glasses) for removing welding slag. 96. Briefly describe the importance of safe production? Answer: Safety is important to * * , enterprises and individuals are very important. Safety production can be said to be the life of the electric power industry, a guarantee for the happiness of employees and their families, an important condition for the steady growth of the benefits of the electric power industry, and an important means to promote the rapid development of the electric power industry and thus maximize the rapid development of the national economy. 97. What safety measures should be taken when overhauling rotary machinery? Answer: When overhauling rotary machinery, safety measures should be taken to prevent rotation, such as cutting off the power supply, cutting off the wind, water, and air sources. All relevant gates and valves should be closed. Warning signs should be hung at the above locations. Reliable braking measures should be taken when necessary. 98. Where should people stand when the trial operation of rotating machinery is started? Answer: The "Safety Work Regulations in the Electrical Industry" clearly stipulates that when the trial operation of rotating machinery is started, except for the operating personnel, other personnel should stay away first and stand in the axial position of the rotating machine to prevent the rotating part from flying out and injuring people. 99. What are the common defects of economizers? Answer: Common defects of the economizer include: outer wall wear, inner wall corrosion, pipe weld leakage and anti-wear device damage, falling off or skewing, the most important of which is outer wall wear 100. What are the main components of the electrostatic precipitator body? Answer: The main components of the electrostatic precipitator body include: smoke box system, corona pole system, dust collection pole system, trough pole system, ash storage system, shell, pipeline, shell insulation and ladder platform 3. Fill in the blanks 1. Adjust the pad iron. Generally, the thick pad should be placed (lower) 2. When the "0" engraved line of the vernier on the vernier scale frame is aligned with the "0" engraved line of the scale body, the distance between the measuring melons is (0) mm 67. Under the same power and speed, the geometric size of the pump is smaller than that of the fan. 3. The low-speed coal mill refers to the (cylindrical mill). 4. When correcting dynamic balancing work on site, the (three-point method) is often used. 5. The blades of airfoil-type high-efficiency fans are generally (back-curved). 6. The rotation speed of medium-speed coal mill is generally between (50-300) r/min. 7. The seals of the rotary air preheater can be divided into (radial seal, axial seal and circumferential seal). 8. When the fan coal mill grinds pulverized coal, it mainly relies on (impact effect). 9. The "30" of No. 30 engine oil refers to (viscosity at the specified temperature) 10. The neck interfaces of the dynamic and static parts of the air duct of the hood rotary air preheater should be concentric, and the non-concentricity should be no more than (3) mm. 12. The upper and lower hoods of the hood rotary air preheater must rotate synchronously, and the measurement error around the hood should be no more than (10) mm. 13. When replacing the pipe, the distance between the two welding joints must not be less than the outer diameter of the pipe, that is, not less than (150) mm. 14. When looking at the axial flow fans from the motor end, they all run in the (clockwise) direction. 15. When hot-loading the bearings, place the bearings in mineral oil (80-90°C) and heat them. 16. The total lengthwise clearance of the steel ball mill bearing bush is generally the shaft diameter (1.5‰~2‰). 17. When grinding tiles, the bright spots on the tile surface indicate (heaviest contact) 18. When using a feeler gauge to measure the gap, the number of plug combinations should not be more than (three pieces) 19. Use gaskets to adjust the height of the equipment, and the gaskets under each foot should not exceed (three pieces) 20. The gap between the impeller front disk and the wind shell of a general centrifugal fan is (40-50) mm 21. Place a level with an accuracy of 0.02mm/m on a 1000mm ruler. If one end of the ruler is raised by 0.02mm, the bubble will shift to (1) grid. 22. The H in the non-ferrous metal grade H62 means (ordinary brass). 23. There is generally a radial clearance of (0.05-0.1mm) between the bearing outer ring and the bearing cap. 24. There must be a certain (radial clearance) between the bearing outer ring and the bearing seat hole. 25. There are two kinds of pins: cylindrical and conical. When the mating section of the pin is checked with red red powder, its contact area (not less than 80%) 26. The working speed of a certain shaft is 3000r/min, and its bearing vibration value is not allowed to exceed (0.06mm) 27. When the rotating speed is 1500r/min, the allowable deviation of the circumference and end face of the elastic coupling alignment wheel shall not exceed (0.08mm)? 28. The matching tightness between the inner ring of the bearing and the shaft is generally (0.02-0.05) mm. 29. The load of lifting machinery and lifting tools is not allowed to exceed ((nameplate regulations) 30. (Carbon dioxide fire extinguishers) are only suitable for extinguishing fires in live equipment below 600V. 31. When encountering strong winds above level (6), it is prohibited to carry out lifting work in the open air. 32. The dust collector currently widely used in thermal power plants in my country is (electrical dust collector) 33. When overhauling the heating surface of the boiler, workers should wait until the temperature of the working area drops below (50)℃ before workers can enter the work. 34. Trauma first aid is in principle (first rescue, then fixation, then transportation), and attention should be paid to taking measures to prevent injuries from being aggravated or polluted. 5. (Too high welding current) will cause burn-through. 36. Welding under conditions that can shrink freely will not produce welding stress. 4. True or False Questions: 1. The cross-sectional view is used to express the cross-sectional shape of the object (×) 2. The part drawing refers to the pattern of the production part (√) 3. The basic cycle of the thermal power plant is the Rankine cycle (√) 4. When reaming a conical hole, it is generally drilled according to the big end (×) ? 5. The dimensions in the plane graphics can be divided into fixed dimensions and positioning dimensions according to their functions (√) 6. The amount of variation allowed by the actual shape of the part surface from the ideal shape is called position tolerance (×) 7. When scraping, the pressure is too high and the scraper edge arc is ground too large, which will produce pits (√) 8. If there is no friction during the state change of the working fluid and under ideal conditions, the increase in entropy value represents the loss of working fluid energy (×) 9. The use of intermediate reheat cycles can improve the thermal efficiency of the cycle, but the exhaust dryness becomes smaller (×) 10. The tool used for reaming is a multi-edged cutting tool (√) 11. The actual size of the part is the size given in the design (×) 12. When the pressure of the same liquid increases, the corresponding saturation temperature rises, and it is easier to vaporize at this time (×) 13. The larger the specific volume of an object of the same volume, indicating that the object is lighter, and the greater the density, indicating that the object is heavier (√) 14. Static electricity only exists when the charged body is insulated (√) 15. The accident lighting power supply of the power plant must be set separately (√) 16. The fuse in the line is made of metal with small resistivity and high melting point (×) 17. Transformer can change the voltage of AC and DC (×) 18. The marking basis should be consistent with the design basis (√) 19. There are three types of three-phase motors: squirrel cage type, wire wound type and synchronous type (√) 20. When two points in the circuit are open, the open circuit voltage is zero (×) 21. The adjustment baffle for the fan inlet and outlet should have a mark on the shaft head that is consistent with the position of the baffle (√) 22. The steam parameters of the boiler generally refer to the pressure and temperature of the steam passing through the superheater outlet (√) 23. According to chemical composition, steel can be divided into low alloy steel and high alloy steel (×) 24. The carbon content of low carbon steel is less than 5% (×) 25. Right-hand threads are much more widely used than left-hand threads (√) 26. The flanges at both ends of the split bearing bush are used to enhance the stiffness of the bearing bush (×) 27. Pulverizing systems are divided into two categories: direct blowing type and storage type (√) 28. The larger the diameter of the impeller of the centrifugal fan, the higher the speed, the higher the pressure head generated (√) 29. The biggest advantage of the steel ball coal mill is that it can grind various types of coal with different characteristics (√) 30. The measurement parts of auxiliary machine vibration are mainly in the bearing shell, casing and foundation (√) 31. Chromium is the most basic element for stainless acid-resistant steel to obtain corrosion resistance (√) 32. When measuring the width of the groove on the part, a depth micrometer can be used (×) 33. When using electric beveling tools, be careful not to feed too much to avoid damaging the motor and breaking the knife (√) 34. The frame level can only test the deviation of the plane from the horizontal position (×) 35. When the air blower blades are worn more than 1/2 of their original thickness, they should be replaced (√) ? 36. The function of the coal feeder is to feed the coal from the original coal hopper evenly into the coal mill according to the quantity requirements (√) 37. According to their composition, metal materials can generally be divided into two categories: pure metals and alloys (√) 38. The types of gaskets are roughly divided into four types: asbestos pads, asbestos rubber pads, copper pads and metal toothed pads (√) 39. Triangular threads are suitable for transmission (×) 40. There are many specifications and varieties of steel, which can generally be divided into four categories: plates, pipes, profiles, and metal products (√) ? 41. The lift of the water pump refers to the total water lifting height of the water pump (√) 42. Both cylindrical pins and conical pins have three functions: positioning, connection and torque transmission, and safety protection (√) 43. SCR medium frequency bending pipe is mainly used to bend carbon steel pipes with larger diameters (√) 44. The electrical conductivity and thermal conductivity of alloys are higher than pure metals (×) 45. Water can be poured on the alloy steel pipe when hot bending (×) 46. The shoulder or collar is positioned reliably and can withstand large axial force (√) 47. Worm drive is suitable for high-power continuous working situations (×) 48. Knowing the code of the rolling bearing, you can know the accuracy level, type and inner diameter of the bearing (√) 49. The inlet throttling adjustment of the fan is more economical than the outlet throttling adjustment (√) 50. The efficiency of the worm drive is higher than that of the belt drive (×) 51. The lifting command signal can be divided into whistle signal, hand signal and gesture signal (√) 52. The rotating part of the hand chain hoist (inverted chain) and the friction bakelite chips should always be oiled to ensure lubrication and reduce wear (×) 53. Once concentrated acid or strong alkali splashes on the human body, first aid should be taken by flushing with a large amount of water (√) 54. There are two types of commonly used welding electrode coatings: alkaline and acidic. Alkaline electrodes generally use DC power supplies, and acidic electrodes generally use AC and DC power supplies (√) 55. The AC current below 50mA is the human body safety current (×) 56. All fire prevention measures are to destroy the combustion conditions that have already occurred (×) 57. The fire protection work policy is "prevention first, combined with fire protection" (√) 58. Welding arc welding is a simple and flexible welding method for welding pure copper, and should be promoted and used (×) 59. The reciprocating speed of the saw blade should be slower when cutting soft materials and faster when sawing hard materials (×) 60. When drawing a circular hole and centering it, it is also necessary to punch holes so that the drill bit can be aligned when drilling (√) 61. When drawing a pattern, the axis and the line of symmetry are two-dot and dash lines (×) 62. Steel rulers and blade rulers can be used to detect both the straightness of the workpiece and the flatness of the workpiece (√) 63. When the operator uses an external caliper to measure the size on the steel ruler, one caliper should be kept close to the end of the steel ruler and the other caliper should swing slightly. The minimum value is the measured size (×) 64. In order to ensure clear processing boundaries and facilitate quality inspection, dense, uniform, large and accurate punch holes should be made on the straight lines and curves drawn (√) 65. When sawing thin-walled pipes, a coarse-toothed saw blade should be used (×)? 66. When the key is matched with the keyway, the top of the keyway should have a tightening force of 0.25-0.45mm (×) 67. When replacing the large gear of the steel ball mill, measures must be taken to prevent rotation due to unbalance when half of the large gear is removed or half of the new gear is installed. 68. When eliminating the remaining static unbalance, the balance weight can only be fixed on the rotor with electric welding (×) 69. During the maintenance of the large tank of the steel ball coal mill, there was accumulated powder in the tank. In order to facilitate the purging of the tank with high-pressure oxygen (×) 70. After the blade repair welding of one fan was completed, a trial operation was required. Before starting, the operator should stand in the axial position of the fan (√) 71. Gaskets can be placed on the joint surface of the bearing and the tile seat (×) 72. The main reason for the large air leakage of the rotary air preheater is the deformation of the preheater, which causes the sealing gap to be too large (√) 73. The output of the coal mill has nothing to do with the ventilation volume (×) 74. When assembling the coupling on site, if it is found that the coupling hole diameter is 0.4mm larger than the diameter of the shaft, the method of adding stainless steel gaskets can be used to replace the assembly tightening force (×) 75. The inlet adjustment baffle must be closed before starting the fan (√) 76. When installing the boiler auxiliary engine, the concrete surface where the pad iron is placed must be chiseled and have good contact with the pad iron (√) 77. The purpose of finding the center of the coupling is to make the two shafts connected together have a common center line of rotation (for rigid shafts) (√) 78. The upper and lower hoods of the hood rotary air preheater must ensure synchronous rotation. When measured around the hood, the error should be no more than 30mm (×) 79. The correct state after alignment of the coupling should be that the outer circle is concentric and the end face is parallel (√) 80. When finding the center of the coupling, a feeler gauge or dial indicator can be used to measure, but the two couplings must be rotated at the same time and the values measured at several positions (√) 81. The adjustment baffle at the fan inlet should be installed along the direction of the air flow, and the opening of the baffle should be consistent with the instructions on the outside (√) 82. After the rolling bearing is installed, qualified lubricating grease needs to be added, and its amount generally accounts for about 2/3 of its space (√) 83. The maximum operating temperature of complex calcium-based grease generally does not exceed 100°C (×) 84. Commonly used greases include calcium-based grease, sodium-based grease and calcium-sodium-based grease (√) 85. The characteristic curve of the fan refers to the relationship curve between the pressure head, power, efficiency and flow rate at a certain rotation speed. In addition, there are flow rate and static pressure, flow rate and surface efficiency curve (√) 86. At the same power and rotation speed, the geometric size of the pump is larger than that of the fan (×) 87. The measurement of the bearing axial clearance can be carried out with a feeler gauge and a dial indicator (√) 88. The inner ring of the rolling bearing fits well with the journal, so when the bearing is pressed into the bearing journal, force should be applied to the inner ring (√) 89. The flexible coupling has the ability to buffer and dampen vibrations (√) 90. When the working machine is overloaded, the belt slips on the pulley, which can provide safety protection (√) 91. Belt transmission and chain transmission are both friction transmissions (×) 92. B-type keyway allows the key to be fixed in the groove better and is the most widely used (×) 93. The function of the fan collector is to prevent foreign matter from entering the fan and damaging the equipment (×) 94. The bearing alloy has good friction reduction properties and is suitable for bearing bushes (×) 95. Do not use jacks with damaged threads or racks (√) 96. Auxiliary safety tools can directly contact the live parts of high-voltage electrical equipment (×) 97. At the scene, there is no need to apply any medicine to the burn wound, such as gentian, mercurochrome and other colored external medicines (√) 98. The low-voltage electroscope is a tool for testing whether low-voltage electrical equipment, electrical appliances or circuits are live. It can also be used to distinguish live wires and ground wires (√) 99. When the electrical components and rotating equipment of the power plant catch fire, carbon dioxide fire extinguishers and sand are not allowed to be used to extinguish the fire (×) 100. Insulating gloves are not required when using electrical tools such as electric drills (×) 101. The grinding head and grinding seat are the only tools for valve maintenance, and the hardness of the materials used should be lower than the hardness of the valve core and valve seat (√) 102. X-ray radiation does not occur during manual arc welding (√)