Section 29 - Process Machinery Drives
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试题二十三一、单项选择题:1.Because the castings of smaller engines are not so big and heavy, ______ and cylinder blockmay be made in one piece.A. the columnB. the jacketC. cylinder coverD. cylinder liner2.______ of an engine crankshaft can be detected by measuring deflections of crank webs foreach unit of the engine.A. MisalignmentB. LengthC. StrengthD. Stresses3. A common trouble with the fuel pump plungers or fuel valve spindle is______.A. broken downB. stuckC. oil leakageD. carbonized4.Diesel fuel oil having a low cetane rating can result in ______.A. improved cold weather startingB. smoother engine operationC. combustion knockD. reduce ignition lag5.______ is arranged for cleaning the lubricating oil in the system and clean oil can beprovided from a storage tank.A. A filterB. A centrifugeC. A distillerD. A generator6.The emulsion of the oil is mainly caused by ______.A. the solid impurities of large particleB. the solid impurities of fine particleC. the water contentD. both water and solidimpurities7.Cylinders of marine diesel engines are normally cooled by ______.A. sea waterB. fine mineral oilC. sanitary waterD. fresh water8.______ are fitted in the exhaust system and facilitate charge removal and scavenging in eachcylinder.A. DiffusersB. CompressorsC. Steam boilersD. Soot blowers9.______ device is provided to prevent starting air from being admitted to the cylinder beforethe reversing is completed.A. An automaticB. A transmissionC. A self-regulatingD. An interlocking10.The difference between a supercharged engine and an un-supercharged engine is that ______operates at an increased pressure.A. the laterB. the latterC. the formerD. the farmer11.______ for attachment to the propeller shaft also accommodates the turning gear and isintegrally forged with the crankshaft.A. The coupling flangeB. The camshaftC. The cross-head pinD. The cylinderjackets12.A(n) ______is a chemical or electro-chemical attack on the metal surface which may befurther increased if the sea-water is polluted.A. errosionB. corrosionC. cavityD. scouring13.The two-stroke cycle begins with the piston coming up from the bottom of its stroke, withscavenge ports in the sides of the cylinder being ______.A. shutB. closingC. openedD. closed14.The governor of a generator engine is to ______.A. make the engine stopB. regulate the timing of camshaftsC. make the rpm stabilize at any required valueD. make the engine run at nearly constant speed15.The ability of the governor to prevent fluctuations(波动) in engine speed is termed ______.A. sensitivityB. stabilityC. promptnessD. speed droop16. A governor automatically controls engine speed by regulating ______.A. fuel supplyB. firing orderC. engine loadD. oil level17.The volute pump is one in which the impeller ___.A. discharges into a gradually widening channelB. has stationary diffuser vanesC. produces no kinetic energyD. All of the aboveare true18.As for a hydraulic single action vane pump, the inner wall of the stator is usually of ______shape.A. circularB. elliptical( 椭圆的)C. rectangular(矩形的)D. hexagon19.Gear pumps are of positive displacement type pumps because they discharge a near constantamount of liquid ______ pressure.A. depending onB. in relative toC. regardless ofD. because of20.If an operating auxiliary boiler has a water pH reading of 7, you should ______.A. bottom blow the boilerB. treat the water with caustic sodaC. treat the water with chemical scavengersD. reduce the water alkalinity to recommended readings21.When steam is being raised on a boiler, the water level will normally ______.A. drop as the boiler warms upB. rise as the boiler warms upC. remain unchanged until the boiler is hot enoughD. rise and fall with the steam demand22.For a purifier, changing to a gravity disc with larger hole diameter will move the interfacetowards the ______.A. bowl peripheryB. bowl centerC. upper surfaceD. lower surface23.When in operation, it is unavoidable that a small amount of oil ______ through leakage, andin order to compensate for these leaks the system is connected to a feed pump.A. escapesB. overheatsC. expandsD.accelerates24.The pollution prevention regulations state that slop oil and sludge that result as part of normalfueling operations should be disposed of by ______.A. discharging ashore into the sewer systemB. sealing in disposable plastic barrels aboard shipC. discharging into a shore tank or slop bargeD. dumping into the ship’s bunker tanks25.If a bilge pump failed to build up discharge pressure, you should check for ______.A. excessive water in the bilgesB. a clogged suction strainerC. oil in the bilgesD. all of the above26.Here some oil in the oily water separator, as a result of its lower ______, will separate andrise into the oil collection space.A. temperatureB. viscosityC. densityD. velocity27.The drive motor will have a brake arranged to fail-safe, i.e. it will ______ the load if powerfails or machine is stopped.A. castB. putC. holdD. let out28.Morring winches are often combined with ______ units so that one prime mover drives both.A. craneB. hatch coverC. windlassD. steering gear29.The air compressor pumps air to the ______.A. air cylinderB. combustion chamberC. steam drumD. expansiontank30.The process of boiling seawater in order to separate it into freshwater vapor and brine isusually defined as ______.A. dehydrationB. condensationC. evaporationD. dissolution31.The cooler as the liquid becomes, ______.A. the faster it will evaporateB. the slower it will condenseC. the slower it will evaporateD. the faster it will flow32.During working, thermostatic expansion valve should be ______.A. either all the way open or all the way closedB. normally fully openC. throttled depending on loadD. controlled by liquefied pressure33.Prior to any overhaul work on electric equipment, it is important to ensure the circuits are______.A. liveB. deadC. excitedD. on line34.Why is it desirable to operate paralleled AC generators at the same power factor?A. Circulating currents are kept to a minimum.B. Field excitation losses are kept to a minimum.C. Generator rotors will have a lesser tendency to hunt.D. Because a power factor increase will decrease kilowatt output.35.In a modern three-phase A.C. synchronous brushes generator, the excitation winding is on therotor. That means ______.A. the generator need not excitation.B. the winding on the rotor is for inputting excitation current.C. there are three phase windings on the rotor.D. the generator has brushes.36.The main generators are connected to ______.A. distribution boardsB. section boardsC. emergency switch boardsD. main switch boardsually the panels are interlocked with ______ so that the devices can be made dead beforethe doors are opened.A. protective earthB. isolatorsC. ground switchD. circuit-breakers38.Which of the listed devices is used to measure pressure and convert it to an electrical signal?A. TransducerB. ReducerC. TransformerD. Rectifier39. A manometer is used to measure ______.A. pressureB. temperatureC. volumeD. specificgravity40.An ohmmeter can be used to measure ______.A. current flow in a circuitB. voltage between two points in a circuitC. circuit continuityD. power41.Engine protection by means of an alarm or shutdown control can be obtained with devicesthat are sensitive to ______.A. temperatureB. pressureC. engine speedD. all of theabove42.When the current in a power transmission line is increased, the power loss ______.A. increases as the square of the currentB. decreases as the square root of the currentC. remains the same, as it is independent of current flowD. increases in direct proportion as the current43.The conclusion that mechanical efficiency is always ______ 100 per cent is correct.A. small thanB. more thanC. little thanD. less than44.In a diesel engine, an extremely leaking exhaust valve can cause ______.A. misfiringB. pre-ignitionC. interrupted scavengingD. reducedscavenging45. A crack in a cylinder liner can be caused by ______.A. worn piston ringsB. installation of undersizedsealing ringsC. operating the engine at low loadsD. restricted cooling water passages46.Poor combustion in a diesel engine can be caused by ______.A. high compression pressureB. low intake air temperatureC. low exhaust pressureD. high scavenge air temperature47.Diesel engine exhaust temperatures may be used to indicate ______.A. leaking exhaust valvesB. an overloaded cylinderC. a clogged injector nozzleD. all of the above.bustion knock can occur in the cylinders of a diesel engine under any conditionpermitting ______.A. a shortened ignition delay periodB. a lean fuel/air mixtureC. excess fuel in the combustion chamberD. rapid vaporization of injected fuel droplets49.During the inspection, the starting air valves should be closed ______ the engine fromturning.A. to increaseB. to speed upC. to preventD. to reduce50.Lower suction pressure of a pump may be caused by ______.A. too much air in the pipe lineB. clogged strainerC. empty tankD. leakypipe51.To prevent excessive _____ in the transverse girders, the tie bolts are positioned as close tothe center of the crankshaft as possible.A. thermal stressesB. bending momentsC. thermal loadsD. surfacetensions52.During repair, lubrication lines and orifices must be ______.A. taken awayB. engagedC. connectedD. sealed off53.If the effective bearing bush area has been reduced ______, remedial action should be taken.A. by more than 5 percentB. by less than 10 percentC. to 95 percentD. to less than 90 percent54. A centrifugal pump can’t supply water after starting. You should check ______.A. priming waterB. power supplyC. packing glandD. bearing lubrication55.The ______ is used to measure current.A. ammeterB. voltmeterC. wattmeterD.frequency meter56.The ______ is used to measure power.A. ammeterB. voltmeterC. wattmeterD. frequency meter57.At the beginning of the watch the current operational parameters and the condition of allmachinery should be verified and also the log readings should correspond with those ______.A. noted by the bridge officerB. told by last duty engineerC. observedD. in the instruction manual58.In the engine department, the ______ is looked upon to provide the leadership that is needed.A. captainB. chief engineerC. chief officerD. chief motorman59.Routine monitoring of a diesel engine should include ______.A. checking for leaksB. checking temperatures andpressuresC. listening for abnormal noisesD. all of the above.60.The stability of a vessel is normally the greatest when all fuel and water tanks are fullbecause the ______.A. center of gravity is loweredB. center of buoyancy is loweredC. reserve buoyancy is unchangedD. hull freeboard is increased61.Hydrocarbon vapors are usually detected by the use of the ______.A. flame safety lampB. combustible gas indicatorC. gasometerD. oxygenindicator62.The order“Bow thrust stop.”means“______”.A. Bow thrust full to portB. Bow thrust full to starboardC. No bow thrust revolutionsD. No stern thrust revolutions63.______ may have two emergency source of power, thus requiring two emergencyswitchboards.A. Large passenger vesselsB. General cargo shipsC. Container shipsD. Oiltankers64. A ______ sometimes called filters, is a device designed to prevent the passage of unwantedsolids into the system.A. steam trapB. check valveC. separatorD. strainer65.It is usual to identify the fluids in pipes by bands of paint at intervals, and the engineer shouldfamiliarize himself with the code in use. According to the above sentence, which of thefollowing statements is true?A. People can know the types of fluids in pipes by feeling with hands.B. There are series of rings painted in the pipes to show various fluids.C. Engineers should wear cards standing for ranks.D. Engineer knows his own code very well.66.One of the disadvantages of using carbon dioxide to extinguish a fire in an enclosed space is______.A. the ‘snow ’which is sometimes discharged along with the gas is toxicB. prolonged exposure to high concentrations of CO 2 gas causes suffocationC. rapid dissipation of the CO 2 vaporD. the CO 2 gas is lighter than air and a large amount is required to extinguish a fire near thedeck67.Administrations should bear in mind the significance(重要性)of ______ in maintainingsafety of life and property at sea and in preventing marine pollution.A. advanced nautical equipmentB. advanced performance main enginesC. emergency equipmentD. communication and language skills68.The SOLAS Convention in its successive forms is generally regarded as the most importantof all international treaties concerning the ______ of merchant ships.A. pollutionB. economizationC. safetyD. efficiency二、关联题(每组关联题题干下有4个小题,每小题4个选项)第一组:At the first start, listen carefully for possible jarring sounds. If anything is suspected, stop the engine immediately, otherwise stop the engine after 5 minutes' idling. Check at least the temperatures of the main and big end bearings and of all other bearings which have been opened. Make visual inspection from below to the cylinder liners and piston skirts which have been opened. If everything is in order, restart.Check that there is no leakage of gas, water, fuel or lubricating oil. Especially observe the fuel lines, HP fuel pumps and injectors. Watch the quantities emerging from the leak oil pipes!Check that the starting air manifold is not hot at any cylinder (leaky starting valve may cause explosion!After overhaul, the following instructions are important:- check pressure and temperature gauges.- check the automatic alarm and stop devices.- check the pressure drop over the fuel filter and lubricating oil filter.- check the oil level in the oil sump/oil tank. Estimate the condition of the oil.- check the de-aerating of the engine circulating water system.- check the quantity of fuel leak.- check the telltale holes for leaks.- check the circulating water quality- check the cylinder pressures.- listen for jarring sounds.- check the crankcase pressure.- check the starting air manifold.Running-in is mainly intended to let piston rings "wear" to fit properly in the cylinder liner.Do not continuously run at constant load during the running -in process.It is important to vary the load several times. The ring grooves in the piston will have a different tilting angle at each load and consequently the piston ring has a different contact line to the cylinder liner wall.69.Paragraph 1 tells us that ______.A. if we hear vibration sounds, we should stop the engine quickly, or allow it to operate atlowspeed for 5 minutes, then stop it and check everythingB. if we hear vibration sounds, we should stop the engine quickly, otherwise the engine willbestopped automatically after 5 minutesC. if we hear explosion sounds we should stop the engine then check everythingD. if we hear surging sounds, we should stop the engine immediately otherwise after 5minutesthe engine will be destroyed70.After overhaul, following instructions are important except ______.A. release air from the engine circulating water systemB. treat the circulating water if necessaryC. make sure the pressure drop is enough besides the fuel filterD. make sure the quantity of lube oil meets the requirement71.After piston overhaul, the running -in process should be carried out ______.A. periodically at steady loadB. occasionally at various loadC. continually at constant loadD. continually at various load72.When dealing with engine troubles, ______.A. no leakage of lubricating oil should be checkedB. quantities of oil emerging from the leak oil pipes must be watchedC. quality of the leak oil must be watchedD. the number of the leaking fuel lines should be checked第二组:At appropriate intervals inspection should be made of the main propulsion plant, auxiliary machinery and steering gear spaces. Any routine adjustments may then be made and malfunctions or breakdowns can be noted, reported and corrected. During these tours of inspection bilge level should be noted, piping and systems observed for leaks, and local indication instruments also be observed.Bridge orders must be promptly carried out and a record of any required changes in speed and direction should be kept. When under standby or maneuvering conditions with the machinery being manually operated the control unit or console should be continuously manned.Certain watchkeeping duties will be necessary for the continuous operation of equipment or plant-the transferring of fuel for instance. In addition to these regular tasksother repair or maintenance tasks may be required of the watchkeeping personnel. However no tasks should be undertaken which will interfere with the supervisory duties relating to the main machinery and associated equipment.During the watch a log or record will be taken of the various parameters of main and auxiliary equipment. Fuel consumption figures are used to determine the efficiency ofoperation, in addition to providing a check on the available bunker quantities. Lubrication oil tank levels to some extent indicates engine oil consumption. If the sump level were to rise this would indicate water leakage into the oil and an investigation into the cause must be made. The engine exhaust temperature reading should all be about the same to indicate an equal power production from each cylinder. The various temperature and pressure values for the cooling water and lubrication oil should be at, or near to, the manufacturer’s designed values for the particular speed or fuel lever settings.(The following questions are based on the passage above)73.The first paragraph mainly about ______.A. what should be done during the watchB. what should be done during tours of inspectionC. what the duty personnel should do when they begin their watchD. all of the above74.The watchkeeping personnel ______.A. should note bilge levelB. should observe piping for leaksC. should undertake required tasks not affecting their supervisory dutiesD. All of the above are true75.Fuel consumption figures are used to ______.A. determine the efficiency of operationB. provide a check on the available bunker quantitiesC. Both A and B are trueD. Neither A nor B is true76.The fourth paragraph is mainly about ______.A. why certain parameters should be recordedB. where to get these readingsC. the purpose to log the sump levelD. all of the above三、中译英(共2题,请将答案写在答题纸上)77.在港口国监督检查中,根据SOLAS 74,下列缺陷可以作为船舶滞留的明显理由:推进及其他关键设备,包括电气装置,不能进行正确操作。
航海英语一:船舶修理一、修理的种类Repair ListsKinds of Repair 修理的种类V oyage Repair 航次修理Annual Repair 岁修修理Guarantee Repair 保修修理Occasional Repair 临时修理Additional Repair 补充修理、加帐修理二、修船英语您好!(第一次见面)How do you do?您好!见到您很高兴。
How do you do? I’m very glad to meet you.让我来介绍一下在座的各位先生。
林先生,我们厂的厂长;王先生,厂长总工;吴先生,船体车间主任。
Let me introduce the gentlemen present here. This is Mr.Lin, our shipyard manager; Mr.Wang, our chief engineer. Mr.Wu, director of the hull shop.欢迎您到我们船厂来!welcome to our shipyard!请坐!Sit down please.好的,谢谢!Thank you.请喝茶。
Please have a cup of tea.喂,您好吗?(熟人之间)Hi, how are you?很好,谢谢。
您好吗?Fine, thank you, and how are you?很好,谢谢!Very well, thanks.我们现在就开始工作好吗?Shall we start our work now?好的。
OK .请这边走。
This way, please.我可以进来吗?May I come in?请进!Yes, please.早晨好,女士。
Good morning, ma’am (Madam).早晨好,布莱克先生。
请坐。
Good morning, Mr.Blake. take a seat, please.谢谢!Thank you, ma’am.请问您有什么事和我商讨?What business would you like to talk with me about?船东想在船上做些变化。
挤出成型英语Extrusion Molding: A Versatile Manufacturing ProcessExtrusion molding is a widely used manufacturing process that has become an integral part of modern industrial production. This technique involves the continuous shaping of raw materials, such as plastics, metals, ceramics, or composites, into a desired cross-sectional profile. The process is characterized by its efficiency, versatility, and ability to produce a wide range of products, from simple tubes and pipes to complex architectural elements and automotive parts.At the heart of the extrusion process is a machinery known as an extruder. This machine consists of a hopper, a barrel, and a screw or ram that drives the material through the barrel. The raw material, in the form of pellets, powders, or liquids, is fed into the hopper and then transported through the barrel by the rotating screw or the linear motion of the ram. As the material moves through the barrel, it is subjected to a combination of heat and pressure, which softens or melts the material, allowing it to be forced through a die at the end of the barrel.The die is the key component that gives the extruded product its desired shape. The die can be designed to create a wide variety of cross-sectional profiles, such as circular, rectangular, or even more complex shapes. The extruded material is then cooled, either by air or water, to solidify the shape and maintain its structural integrity.One of the primary advantages of extrusion molding is its ability to produce parts with a consistent and uniform cross-section. This is particularly important in applications where precise dimensional control is required, such as in the production of pipes, window frames, or electrical conduits. Additionally, extrusion molding is a highly efficient process, as it can produce large quantities of parts with minimal waste and at a relatively low cost.Another significant advantage of extrusion molding is its versatility. This process can be used to manufacture a wide range of products, from simple plastic bags to complex composite materials used in the aerospace industry. The choice of raw material is also diverse, with plastics, metals, ceramics, and even food products being commonly extruded.In the field of plastics, extrusion molding has become a dominant manufacturing technique. Thermoplastic materials, such as polyethylene, polypropylene, and PVC, are extensively used in extrusion processes to create a variety of products, including pipes,sheets, films, and profiles. The ability to continuously extrude these materials makes the process highly efficient and cost-effective, contributing to its widespread adoption in the plastics industry.Beyond plastics, extrusion molding is also used in the production of metal and ceramic products. In the metal industry, extrusion is used to create a wide range of shapes, from simple rods and tubes to complex architectural elements and automotive components. The process is particularly useful for shaping hard-to-machine materials, such as aluminum and titanium. In the ceramic industry, extrusion is used to produce bricks, tiles, and other structural components, taking advantage of the material's ability to be shaped and formed under high pressure and temperature.Extrusion molding also plays a crucial role in the development of composite materials. These materials, which combine two or more distinct components, can be extruded to create products with enhanced mechanical, thermal, or electrical properties. The continuous nature of the extrusion process allows for the uniform blending and shaping of these composite materials, making it an essential technique in the production of advanced engineering materials.As technology advances, the extrusion molding process continues to evolve, with improvements in machinery, die design, and processcontrol. These advancements have led to the development of specialized extrusion techniques, such as co-extrusion, which allows for the simultaneous production of multiple layers or materials within a single extruded product. Additionally, the integration of computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies has further enhanced the precision and efficiency of extrusion molding, enabling the production of increasingly complex and customized parts.In conclusion, extrusion molding is a versatile and efficient manufacturing process that has become indispensable in a wide range of industries. Its ability to continuously shape raw materials into a variety of cross-sectional profiles, coupled with its cost-effectiveness and scalability, has made it a dominant force in the production of a diverse array of products, from everyday consumer goods to high-performance engineering components. As the demand for innovative and customized products continues to grow, the importance of extrusion molding in the manufacturing landscape is poised to remain strong for years to come.。
Heat of compression rotary drum dryersMD series (200-4000 l/s, 424-8480 cfm)ND series (300-4000 l/s, 636-8480 cfm)MDG series (450 l/s, 954 cfm)Cost-effective dry airfor your applicationClean and dry compressed air is vital to power up your busyproduction environment. Containing moisture, aerosols and dirtparticles, untreated compressed air poses a substantial risk as it candamage your air system and end product. Y et it must be producedreliably, energy-efficiently and cost-effectively. Atlas Copco’s heat-ofcompression rotary drum dryers protect your systems and processes.Their robust design ensures they operate with total reliability anddeliver the desired quality of air.MDG 450By removing moisture from compressed air with a pressure dewpoint as low as -45°C/-49°F , MD, MDG and ND heat-of-compression rotary drum dryers eliminate system failures,production downtime and costly repairs.Atlas Copco's proven rotary drum technology ensures maximum reliable process continuity thanks to the use of high-quality materials. In addition, its simple design eliminates any risk of losses and advanced control and monitoring is available for optimal energy efficiency.As the heat-of-compression is used to dry the desiccant, limited energy is required for drying. The energy required to rotate the drum is negligible. Furthermore, there is no loss of compressed air, ensuring 100% flow capacity at output. The rotary drum dryers are characterized by zero purge by design, an extremely low pressure drop and no filtration requirements.The combination of an easy-to-service vessel, minimalmaintenance downtime and long service intervals reduces your maintenance time and costs. The dryers have a small footprint thanks to an innovative all-in-one design. Installation is straightforward, minimizing costly production downtime.Through continuous investment in our competent, committed and efficient service organization, Atlas Copco ensures superior customer value by maximizing productivity. With a presence in over 180 countries, we offer professional and timely service through interaction and involvement. Uptime is guaranteed by dedicated technicians and 24/7 availability.Protecting your reputation and productionKeeping your production up and runningDriving down energy costsEasy installation and long maintenance intervalsAssuring your peace of mind3The presence of moisture during the preparation of foods and beverages can cause contamination of end products.Processing machinery can also be affected by moisture,which interferes with their operation and obstructs the free and easy movement of the ingredient or item of food.Food & beverageA reliable supply of dry airAll kinds of power plants rely on compressed air to operate pneumatically controlled valves and other components. High-quality dry air can be the key to achieving plant productivity and cost savings when you need them most, and keeping an operation running effectively during a period of maintenance or emergency.Power generationA focus on productivityMDG 450Strict moisture control is a key factor in the manufacture of most pharmaceuticals. Many materials used to produce pharmaceuticals have a physical affinity for moisture, which can cause powdered material to aggregate. Other powders that are formed into a tablet under high pressures will adhere only when in a dry state. Humidity can cause a tablet to crumble or the drug to decompose and diminish in its therapeutic value. To assure consistently high-quality drugs, the presence of dry air in the processing area and machinery is therefore vital.PharmaceuticalsA tight control on qualityFor process industries, high-quality dry air is vital for efficient pneumatic and instrumentation control. A dependable stream of high-quality dry air is essential to keep the production up and running at all times.Process airA continuous flow of dry airThe oil-free air ZR compressors are perfect for the highly sensitive production processes in the textile industry.This high-quality air is used in a variety of textile applications such as spinning, weaving, dyeing,texturizing, winding and coning.T extilesCLASS 0 certified air quality5Compressed air leaving the compressor is almost always 100%saturated. Excessive moisture in compressed air can have damaging effects on the facility and jeopardize the effectiveness of operations. To avoid excessive and unnecessary maintenance costs and potential production shutdown, it is recommended to be proactive and properly implement the necessary steps to keep the compressed air dry, clean and suitable for any given process and or application.Water to the air net if no dryerinstalledEnergy can constitute up to 80% of the total lifecycle cost of a dryer. Y ou therefore need to look closely at energy efficiency when selecting a dryer. The illustration compares the lifecycle cost of heatless, blower purge and rotary drum dryers.Lifecycle costIf a desiccant dryer experiences a high internal pressure drop, the compressor discharge pressure must be set higher than required,which wastes energy and increases operating costs. Atlas Copco has therefore put considerable efforts into minimizing pressure drops in its dryers. Compared to twin tower dryers, the system pressure drop is very low.Low pressure dropMDG 450•Regeneration air cooler: stainless steel for water-cooledversions; aluminium for air-cooled versions •Integrated in the dryer•Stainless steel pipes, high strength at reduced weight •Resistant to corrosion without special protective coating•Interface available in 32 languages •Comprehensive maintenance display •Stainless steel cooler keeps performance over the lifetime of the dryer•Requires minimum maintenance•Easy to clean•Greased for life electric motor which drives the rotating drum (Variable Speed Drive is optional on selected models)•No blower/pump, no heater - no additional power consumption •-40°C/°F and lowerHigh reliabilityResistant to corrosionUser-friendly monitoring system Lifetime guaranteed performancelevelMinimal power consumption Guaranteed pressure dew point7Superior energy efficiencyWhereas other desiccant dryer types can consume up to 20% of the compressed air, the rotary drum dryers guarantee 100% flow capacity at the output.Zero purge by designThe combination of an easy-to-service vessel, minimal maintenance downtime and long service intervals reduces your maintenance time and costs. In addition,there is no need to change filter cartridges.Low maintenanceRotary drum dryers need no pre-filters, no after-filters and no dust filters, all of which can cause pressure drops. Typically a set of pre- and after-filters can have an average pressure drop exceeding 0.5 bar and lead to an extra 3.5% energy consumption.No filtration requirementsMDG 450The small footprint of rotary dryers means they take up minimal space in your facility.They come in a completely integrated package; all piping and connections are included as standard. A convenient lifting eye makes them easy to maneuver.Complete, compact packageThe controller adapts the heating power to the required minimum to achieve the requested performance.Smart heating and best performance (ND only)Rotary drum dryers are totally oil-free and use no Freon or CFCs, and a minimal amount of desiccant (only 5-10% of conventional adsorption dryers). 95% of all components can be recycled, and the units have very low noise levels.Environmentally friendly9The full flow of hot compressed air leaves the last stage of the compressor and passes through the MDG’s heat exchanger (2) and the water-cooled cooler (3). Cooled compressed air (branch 4) enters the drum for drying. Dry air comes out at the top, where it leaves the MDG at point 5. Part of the dry air (branch 6) goes into the heat exchanger (2), where it picks up the heat from incoming compressed air (branch 1). Dry and hot regeneration air (branch 7) passes through the regeneration section of the drum, where the moisture is removed. Wet and hot regeneration air is cooled in the regeneration cooler (8) and then mixed with the incoming cooled compressed air (branch 4).MDG working principleThe MD’s working principle is based on using hot compressed air from the compressor to regenerate the desiccant. The single pressure vessel is divided into two sectors: drying (75%) and regenerating (25%). Desiccant, impregnated on a honeycomb glass fiber drum, slowly rotates through these two sectors. Hot air leaving the last stage of the compressor is divided into two streams, 1 and 2. The main stream – branch 1 – passes through the compressors after cooler (not visible in the image) and enters the dryer for drying. The regeneration stream – branch 2 – (hot unsaturated air) is headed for desiccant regeneration. It passes through the regeneration section of the drum, removes the moisture through desorption and regenerates the desiccant. The now saturated regeneration air flow is cooled in the regeneration cooler (3), and then mixed with the main stream (branch 1).MD working principle MDG 450The difference with the MD working principle is that the regeneration stream – branch 2 – (hot unsaturated air) is split in two, the first part passes directly through the regeneration sector of the desiccant drum. The second part passes through the regeneration heater 6, is further heated and moves to the regeneration sector to achieve deeper dew points. Both flows are passing through the regeneration sector of the drum, removing the moisture through desorption; the desiccant is regenerated. The saturated regeneration air flow is cooled in the regeneration cooler 3 and then mixed with the main stream (branch 1). The controller adapts the heating power to the minimum required to achieve the requested performance.ND working principleThanks to their pioneering technology, rotary drum dryers ensure the lowest pressure drop and lowest energy consumption for the highest possible efficiency – saving you time and money throughout the production process. The uniqueness of the rotary drum dryers lies in the fact that the loss of compressed air is completely avoided. Due to the usage of the generated heat from the compression process, a minimal amount of power is required to achieve very low dewpoints.Savings when selecting the right drying method11The Elektronikon ®unit controller is specially designed to maximize the performance of your compressors and air treatment equipment under a variety of conditions. Our solutions provide you with key benefits such as increased energy efficiency, lower energy consumption, reduced maintenance times and less stress… less stress for both you and your entire air system.Elektronikon ®MK5 GraphicHigh resolution color display gives you an easy to understand readout of the equipment’s running conditions.•Clear icons and intuitive navigation provides you fast access to all of the important settings and data.•Monitoring of the equipment running conditions andmaintenance status; bringing this information to your attention when needed.•Operation of the equipment to deliver specifically and reliably to your compressed air needs.•Built in remote control and notifications functions provided as standard, including simple to use ethernet based communication.•Support for 31 different languages, including character based languages.Intelligence is part of the packageMonitor your compressors over the ethernet with the Elektronikon ®unit controller. Monitoring features include warning indications,compressor shut-down and maintenance scheduling. An Atlas Copco App is available for iPhone/Android phones as well as iPad and Android tablets. It allows fingertip monitoring of your compressed air system through your own secured network.Online monitoringMost production processes create fluctuating levels of demand which, in turn, can create energy waste in low use periods. Using the graphic Elektronikon ®unit controller, you can manually or automatically create two different system pressure bands to optimize energy use and reduce costs at low use times.Dual pressure set-pointMDG 450Monitor your compressed air installation with SMARTLINKKnowing the status of your compressed air equipment at all times is the surest way to achieve optimal efficiency and maximum availability.Go for energy efficiencyCustomized reports on the energy efficiency of your compressor room.Increase uptimeAll components are replaced on time, ensuring maximum uptime.Save moneyEarly warnings avoid breakdowns and production loss.SMARTLINKSMARTLINK ServiceA mouse-click reveals the online service log. Get quotes for parts and additional service quickly and easily.SMARTLINK UptimeUptime additionally sends you an e-mail or text message whenever a warning requires your attention.SMARTLINK EnergyEnergy gives you customized reports on the energy efficiency of your compressor room, in compliance with ISO 50001.Evolving towards compressed air management13Minimizing Excess PressureOptimizer 4.0 minimizes the generation of excess compressed air by starting and stopping compressors.Its user friendly interface enables you to set multiple pressure bands, allowing you to optimize your compressor installation for varying circumstances, such as non-productive hours.Full VSD BenefitsWith Optimizer 4.0 you can realize the full energy saving potential of VSD (Variable Speed Drive). It regulates the VSD to ensure that the compressed air output is proportional to the demand, preventing higher pressures than required, excess unloaded running, and spiraling energy costs.Improving UptimeOptimizer 4.0 effectively eliminates production downtime caused by unexpected system pressure drops,because it regulates the system pressure instead of the compressor output pressure.This means Optimizer 4.0 will automatically adjust the system pressure to compensate for pressure drops due to filters, piping and dryers for example.Optimizing Wear and T earOptimizer 4.0 comes in different variants, for up to 4, up to 8 or over 8 machines and centrifugals.We also provide additional functionality and services on Optimizer 4.0 to ensure that your energy savings will stand the test of time. Even when your installation needs adaptations or your demand changes.Optimize your compressed air systemMDG 450AIRnet, compressed air piping systemAIRnet is a fast, easy and reliable piping solution that guarantees operational excellence for compressed air, vacuum, nitrogen and other inert gas applications.AIRnetFastThanks to a smart piping design and low weight materials, AIRnet can be installed 70% faster than conventional systems EasyAIRnet pipes and fittings are assembled in just a few steps by a single installer, without the need for heavy machinery ReliableHighly durable and corrosion-free, AIRnet aluminum pipes and fittings come with a 10-year warrantyFast, easy, reliableIf you look at your total cost of ownership, AIRnet will turn out to be the best investment choice you can make. It is a high-end aluminum system specially designed to save the money that other piping systems spend. Its piping network is engineered to support sustainable operational excellence in your production process. Material and product design, installation and maintenance costs, flexibility and safety - they all influence your total cost of ownership and the level of efficiency in your production.Operational excellenceAIRnet connections are corrosion-free, low friction and seamless to minimize pressure drop, boosting your compressed air energy efficiency.Maximized energy efficiency15For any existing piping networkThe piping system can be connected to any existing network and it can be modified easily to meet any changes on the industrial floor. All AIRnet components are easily adjustable and reusable to facilitate future network extensions.Compressor line filtersIf your application relies on the cleanest compressed air, our line filters and filter cartridges will make that happen with optimal efficiency.Minimize pressure dropsOur filters reduce pressure drop by 40% and save on energy consumption.Long lifetimeEnjoy a longer lifespan by using genuine filters.ISO-CertifiedQuality validated independently by TÜV.MDG 450Optimize your systemScope of supply- : Not available: Standard• : OptionalRotary drum adsorption dryers MD 200-4000Rotary drum adsorption dryer MDG 450Rotary drum adsorption dryers ND 300-4000Notes21MDG 45023COMMITTED TO SUSTAINABLE PRODUCTIVITY We stand by our responsibilities towards our customers, towards theenvironment and the people around us. We make performance standthe test of time. This is what we call – Sustainable Productivity.。
ISIC Rev. 4 Section C: “Manufacturing”Review of new divisions26-28Manufacturing in ISIC Rev.4☐Manufacturing as a “historical” area remains relatively stable☐Application rules remain mostly intact⏹top-down approach⏹vertical integration⏹outsourcing☐Changes in detail for manufacturing:ISIC Rev.3.1ISIC Rev. 4Sections11Divisions2324Groups6171Structural changes in the manufacturing section of ISIC Rev.4☐There are different kind of structural changes:⏹Splitting of existing divisions, i.e. elevating activities to ahigher level☐Examples:⏹food and beverage manufacturing⏹furniture manufacturing⏹pharmaceuticals⏹Separation of certain activities, i.e. recognition as separateactivities☐Examples:⏹repair and maintenance⏹installation of machinery and equipment⏹Complete reorganization of a cluster of activities☐Example:ISIC Rev.4 divisions 26 –28☐ISIC Rev.4 introduces 3 completely new manufacturing divisions:⏹26 –Manufacture of computer, electronic and optical products⏹27 –Manufacture of electrical equipment⏹28 –Manufacture of machinery and equipment n.e.c.☐To a large extent, these divisions consist of a reorganization of the content of ISIC Rev.3.1 divisions:⏹29 –Manufacture of machinery and equipment n.e.c.⏹30 –Manufacture of office, accounting and computingmachinery⏹31 –Manufacture of electrical machinery and apparatus n.e.c.⏹32 –Manufacture of radio, television and communicationequipment and apparatus⏹33 –Manufacture of medical, precision and optical instruments,24–chemical products2114 25–rubber / plastics products1113613 26–non-metallic mineralproducts27–basic metals5 28–fabricated metal products1710321295 29–machinery / equipmentn.e.c.21130–office, accounting,computing machinery31–electrical machinery n.e.c.51429371152 32–Radio, TV, communicationequip.61396 33–medical, precision,optical114 34–motor vehicles, (semi-)trailers35–other transport equip.46824–chemical products2114 25–rubber / plastics products1113613 26–non-metallic mineralproducts27–basic metals5 28–fabricated metal products1710321295 29–machinery / equipmentn.e.c.21130–office, accounting,computing machinery31–electrical machinery n.e.c.51429371152 32–Radio, TV, communicationequip.61396 33–medical, precision,optical114 34–motor vehicles, (semi-)trailers35–other transport equip.46826–computers / electronics / optical equip.24–chemical products 225–rubber / plastics products 126–non-metallic mineral products27–basic metals28–fabricated metal products29–machinery / equipmentn.e.c.30–office, accounting, computing machinery231–electrical machinery n.e.c.532–Radio, TV , communication equip.733–medical, precision, optical634–motor vehicles, (semi-) trailers35–other transport equip.ISIC 4ISIC 3.127–electrical equipment 28–machinery / equip. n.e.c.33-repair Other divisions 11411361351710321295111429311521396114468Division 26: Computer and Electronic and OpticalManufacturing Draws together the manufacture of electronic products, such as:-semiconductors-integrated circuits-electronic capacitors -printed circuit boards -electronic connectors-computers and computer peripherals -consumer electronic products -communications equipment -electronic instruments-high-tech medical equip. (MRI, PET)-magnetic and optical mediaThese items are brought together in one division because of:-Similar production processes-Keen interest in tech. manufacturing -outdated practices in ISIC Rev.326–computers / electronics / optical equip.24–chemical products 225–rubber / plastics products 126–non-metallic mineral products27–basic metals28–fabricated metal products29–machinery / equipment n.e.c.30–office, accounting, computing machinery231–electrical machinery n.e.c.532–Radio, TV , communication equip.733–medical, precision, optical634–motor vehicles, (semi-) trailers35–other transport equip.ISIC 4ISIC 3.1Division 26: Computer and Electronic and OpticalManufacturing•261-Manufacture of electronic components and boards•262 –Manufacture of computers and peripheral equipment•263 –Manufacture of communication equipment•264–Manufacture of consumer electronics•265 –Manufacture of measuring,testing, navigating and control equipment; watches and clocks•266–Manufacture of irradiation, electromedical and electrotherapeutic equipment•267–Manufacture of opticalinstrument and photographic equipment •268–Manufacture of magnetic and optical media24–chemical products25–rubber / plastics products 26–non-metallic mineral products27–basic metals28–fabricated metal products29–machinery / equipment n.e.c.30–office, accounting, computing machinery31–electrical machinery n.e.c.32–Radio, TV, communication equip.33–medical, precision, optical34–motor vehicles, (semi-) trailers35–other transport equip.Manufacturing•261-Manufacture of electroniccomponents and boards•262 –Manufacture of computers andperipheral equipment•263 –Manufacture of communicationequipment•264–Manufacture of consumerelectronics•265 –Manufacture of measuring,testing, navigating and control equipment;watches and clocks•266–Manufacture of irradiation,electromedical and electrotherapeuticequipment•267–Manufacture of opticalinstrument and photographic equipment•268–Manufacture of magnetic andoptical media22576131411Draws together the manufacture ofa range of electric (and somenonelectric) equipment, such as:-electric motors-electric generators-electric distribution transformers-electric distribution capacitors-batteries-electrical wiring devices-lighting equipment-domestic appliances-other electrical equipmentGrouped separately fromelectronics because of:-different production processes-different producers-similar production processes as agroup-need to regroup remaining activities24–chemical products25–rubber / plastics products 26–non-metallic mineral products27–basic metals28–fabricated metal products29–machinery / equipment n.e.c.30–office, accounting, computing machinery31–electrical machinery n.e.c.32–Radio, TV, communication equip.33–medical, precision, optical34–motor vehicles, (semi-) trailers35–other transport equip.Manufacturing•261-Manufacture of electroniccomponents and boards•262 –Manufacture of computers andperipheral equipment•263 –Manufacture of communicationequipment•264–Manufacture of consumerelectronics•265 –Manufacture of measuring,testing, navigating and control equipment;watches and clocks•266–Manufacture of irradiation,electromedical and electrotherapeuticequipment•267–Manufacture of opticalinstrument and photographic equipment•268–Manufacture of magnetic andoptical media22576131411•271–Manufacture of electric motors,generators, transformers and electricitydistribution and control apparatus•272–Manufacture of batteries andaccumulators•273–Manufacture of wiring and wiringdevices•2731–Manufacture of fibre opticcables•2732–Manufacture of otherelectronic and electric wires and cables•2733–Manufacture of wiring devices •274–Manufacture of electric lightingequipment•275–Manufacture of domesticappliances•279–Manufacture of other electricalequipment•2790–Manufacture of other electricalequipmentNew industry: 273 –“Manufacture of wiring andwiring devices”New industry: 2790 –“Manufacture of other electrical24–chemical products 25–rubber / plastics products26–non-metallic mineralproducts 27–basic metals28–fabricated metal products29–machinery / equipmentn.e.c.30–office, accounting, computing machinery31–electrical machinery n.e.c.32–Radio, TV , communicationequip.33–medical, precision,optical34–motor vehicles, (semi-)trailers35–other transport equip.36–furniture; other manufacturing n.e.c.ISIC 4ISIC 3.127electrical equipment 3141Division 27: Manufacture ofelectrical equipment•271–Manufacture of electric motors,generators, transformers and electricity distribution and control apparatus•272–Manufacture of batteries and accumulators •273–Manufacture of wiring and wiring devices •2731–Manufacture of fibre optic cables•2732–Manufacture of otherelectronic and electric wires and cables •2733–Manufacture of wiring devices •274–Manufacture of electric lighting equipment•275–Manufacture of domesticappliances•279–Manufacture of other electrical equipment •2790–Manufacture of other electrical equipment Division 28: Manufacture of machinery and equipment n.e.c.•281 –General-purpose machinery •2811 –Engines and turbines •2812 –Fluid power equipment •2813 –Pumps, compressors, valves •2814 –Bearings and gears •2815 –Ovens and furnaces•2816 –Lifting and handling equip.•2817 –Office machinery and equip. •2818 –Power-driven hand tools •2819 –Other general-purpose mach.•282 –Special-purpose machinery•2821 –Agricultural/forestry mach.•2822 –Metal-forming machinery, machine tools •2823 –Machinery for metallurgy •2824 –Machinery for mining, quarrying and construction •2825 –Machinery for food, beverage and tobacco processing •2826 –Mach. for textile, apparel and leather production2829 –Other special-purpose machinery28–machinery / equip. n.e.c.111211213143New class: 2812 –”Manufacture of fluid powerequipment”Manufacture of weapon andammunition no longer with ”Special -purpose machinery”26–computers / electronics / optical equip.27–electricalequipment28–machinery /equip. n.e.c.33-repairOtherdivisions24–chemical products2114 25–rubber / plastics products11136 26–non-metallic mineralproducts13 27–basic metals5 28–fabricated metal products171029–machinery / equipmentn.e.c.32129530–office, accounting,computing machinery21131–electrical machinery n.e.c.51429332–Radio, TV, communicationequip.7115233–medical, precision, optical6139634–motor vehicles, (semi-)trailers114 35–other transport equip.46836–furniture; other manufacturing n.e.c.13424 ISIC 4ISIC 3.1。
—MARINEDrives and motors for electrically driven deck machinery and offshore winches• Working in close cooperation with winch manufacturers,we've incorporated our extensive experience into the drivesthat work with various marine and offshore winch types.• Pair our drives with our LV marine motors for a one-stop supplierthat is backed by a global service and support network.2M A R I N E B R O CH U R E—Performance. Speed. Reliability. Safety.Everything counts.With the help of application expertise gained over many years, we’ve developeddrives and motors that enable precise, smooth, dependable, and safe winch operation, while reducing wear on the ropes and winch. Because everything counts.Anchoring/mooring winchesThe built-in winch control program of our ACS880 drives includes features like anchor control, hand mooring mode, automooring mode, clutch control mode, mechanical brake control, and master-follower operation (for controlling multiple winches). 1 Winch control is included in the drive – no need for external controllers (located in the winch cabinet of the electrical room)2 Full control of speed and torque without a shaft encoder3 Automooring is possible without a load cell sensor4 Multiple control stands connect directly to the driveDeck machinery winch solution with +N5100 software option1234Deck machinery winches are used for anchor handling with a chain or for mooring by maintaining rope tension.The main benefits of an electrically driven winch include precise, smooth, dependable and safe winch operation. In addition, the electrical winch control reduces wear on the ropes and the winch.Deck machinery solutions typically have an open loop motor control (without an encoder) and S2-30% motor duty without motor cooling (IC-410). The open loop motor control is an advantage especially in harsh environment due to simpler installation with fewer parts. *)*) The performance of the winch needs to be verified and approved between ABB and the winch manufacturer. In the case of hoisting machinery, a closed loop control with a motor encoder is required.D R I VE S A N D M OTO R S FO R EL EC TR I C A L LY D R I V EN D ECK M ACH I N ER Y A N D O FFSH O R E W I N CH E S 3Offshore machinery winch solution with +N5800 software optionTugboat towing winchesEscort and push mode operations for safe tugboat control. HMIActive Heave Compensation (AHC)AHC is built into the drive for controlling the remotely operated vehicle (ROV) and launch and recovery system (LARS) winches. The MRU is connected directly to the drive via an Ethernet interface.Offshore machinery winches are used for applications such as:• Towing (escort tow & push tasks)• Fish trawling (dragging & pulling tasks based on true line force)• Umbilical & tether cable management• Active Heave Compensation (AHC) for LARS & oceanographic operationsOffshore machinery solutions always require an encoder on the motor shaft or drum main shaft. Furthermore, the drive rating needs to be oversized to compensate for intermittent peak performance requirements. Since these applications require the motor to constantly perform close to 0 rpm, the motor duty and cooling options need to be considered. *)*) The performance of the winch drive needs to be verified and approved between ABB and the winch manufacturer.4M A R I N E B R O CH U R E—ACS880 drives with built-in winch control software Minimize your engineering timeOur marine-certified ACS880 drives provide reliable operation and performance where it’s needed the most. Offering accurate speed and torque control for a wide range of motor types, they are suitable for new installs and retrofits of existing winches.ACS880 drives are available in the 0.55 to 6000 kW range and voltages of 400, 440, 500 and 690 V. Enclosure class options include: IP20, IP21, IP22, IP42, IP54 and IP55.Removable memory unitStores the drive’s software and settings for fast and easy commissioning and maintenance.ACS880 marine winch control software ordering codes • For deck machinery, anchoring/mooring and multi-motor/master-follower winches: +N5100• For offshore, tugboat and AHC winches: +N5800 (limited release)Understanding the effects of harmonic distortionAny distorted voltage and current waveform that deviates from the ideal sinusoidal waveform has the potential to damage electrical components, which can result in costly repairs and equipment downtime. All non-linear loads connected to the electrical supply in industrial and commercial facilities insert waveform distortions called harmonics on the power distribution system. Commonnon-linear loads include solid-state motor soft starters, standard variable speed drives, computers, LED lighting, welding supplies, and uninterruptible power supplies. Harmonics negatively affect power networks and connected equipment. The higher the harmonic content, the higherthe line current, which means higher losses in the network, including its components like transformers, switches, circuit breakers, and cables. In addition, the increased line current means that the power network equipment overheats, which leads to premature failure. Furthermore, harmonics witha distorted current mean there is also a risk of connectedequipment malfunctioning and failing.—A pure sinusoidal voltage and current does not contain any harmonics.—A voltage and current that deviate from the sine form contain harmonics.D R I VE S A N D M OTO R S FO R EL EC TR I C A L LY D R I V EN D ECK M ACH I N ER Y A N D O FFSH O R E W I N CH E S5 Helping to keep the vessel’s network cleanNow, the ultra-low harmonic and regenerative ACS880drives are also available with marine type approvals.Both of these drive types help to keep the vessel’selectrical network clean from unwanted disturbancesby producing exceptionally low harmonic content.Furthermore, the ACS880 regenerative drives help tosimplify the installation by eliminating the need foran external braking resistor.Key benefits of ACS880 ultra-low harmonicand regenerative drives• The total harmonic current distortion is typically<3% in a nominal situation in an undistorted network.In partial loads, the harmonic content is also low.• Unity power factor. Network power factorcorrection is also possible.• The active supply unit in the drive can boost theoutput voltage, which ensures reliable operationand guarantees full motor voltage, even whenthe supply voltage is below nominal• No need for external filters, multi-pulsearrangements or special transformersWith ACS880 regenerative drives you’ll also get these:• 100% of the power can be regenerated continuously • Significant energy savings compared to other braking methods• No need for external braking devices, which makes drive installation simple and requires less cabinet space —ACS880 ultra-low harmonic and regenerative drives are now available with marine type approvals.—ACS880 ultra-low harmonic and regenerative drives Keeping the network clean while saving energy6M A R I N E B R O CH U R E—Low voltage marine motors for winchesMade to last in demanding conditionsOur range of open-deck motors are designed to withstand salt, humidity, and waves washing over the deck. They deliver reliably high performance foryour winches, day after day.Key benefits of ABB’s low voltage brake motors for winches:• Our motors are designed to comply with stringent safety criteria while providing the highestreliability. At the same time, special attention is paid to marine classification requirements.• ABB Marine Process Performance brake motors consist of three flexible designs for customized configurations: 1) totally enclosed non-ventilated TENV (IEC 410); 2) totally enclosed fan cooledTEFC (IEC 411); 3) enclosed forced ventilated TEFV (IEC 416).• IP56 open deck protection (highest protection class for motors, standard IP56 is not adequate).• Built-in marine IP67 brake options from all major brake manufacturers.• Selection of encoders designed for harsh marine and offshore conditions.• Wide range of painting systems, including the NORSOK-approved system.• Availability of a watertight enclosure IP67 open deck-type terminal box.• Robust, low-temperature-resistant designs can be supplied for vessels that operate inArctic or Antarctic waters. Ex-protected versions are also available.D R I VE S A N D M OTO R S FO R EL EC TR I C A L LY D R I V EN D ECK M ACH I N ER Y A N D O FFSH O R E W I N CH E S7 Typical electrically driven winch motor performance (with an induction motor)Available motor technologies for winches – induction, permanent magnet, SynRM and PMaSynRM motors3A U A 0000157570 R E V D E N 10.1.2022© Copyright 2022 ABB. All rights reserved.Specifications subject to change without notice.—For more information, please contact your local ABB representative or visit/drives/segments/winches/motors-generators/segments/marine。
ELECTRIC MOTORS AND AUXILIARIESAlternating-Current Motors, Constant Speed. . . . . . . . . . . . . . . . . . . . . 29-4Alternating-Current Squirrel-Cage Induction Motors . . . . . . . . . . . . 29-4Synchronous Alternating-Current Motors. . . . . . . . . . . . . . . . . . . . . . 29-6Alternating-Current Motors, Multispeed . . . . . . . . . . . . . . . . . . . . . . . . 29-7Two-Winding Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-7Single-Winding Consequent-Pole Motors. . . . . . . . . . . . . . . . . . . . . . 29-7Four-Speed, Two-Winding Squirrel-Cage Motors . . . . . . . . . . . . . . . 29-7Pole-Amplitude-Modulated Induction Motors. . . . . . . . . . . . . . . . . . 29-7Alternating-Current Motors, Wound-Rotor Induction. . . . . . . . . . . . . . 29-7Direct-Current Motors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-8Adjustable-Speed Drives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29-9Motor Enclosures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-9Motor Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-10Types of Starters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-10Motor Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-11Special Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-13RECIPROCATING ENGINESSteam Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-14Internal-Combustion Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-14Design Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-14Operating Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-15Installation and Costs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29-1629-1*Based largely on material originally compiled and contributed by Carl R. Olson, M.S.E.E.†Based largely on material originally compiled and contributed by Frank L. Evans, Jr., B.S.M.E., L.L.B. (Reciprocating Engines), and H. Steen-Johnsen, M.S.M.E.(Steam Turbines).STEAM TURBINESTypes of Steam Turbines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-17 Straight Condensing Turbine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-17 Straight Noncondensing Turbine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-17 Nonautomatic-Extraction Turbine, Condensing orNoncondensing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-17 Automatic-Extraction Turbine, Condensing or Noncondensing. . . . 29-17 Automatic-Extraction-Induction Turbine, Condensing orNoncondensing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-17 Mixed-Pressure Turbine, Condensing or Noncondensing. . . . . . . . . 29-17 Reheat Turbine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-17 Stage and Valve Options. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-17 Types of Blades and Staging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-18 Performance and Efficiency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-18 Steam Rate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-20 Turbine Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-20 Control-System Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-21 Speed-Control Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-21 Extraction-Pressure Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-22 Selecting a Turbine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-22 Test and Mechanical Performance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-27 Operating Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-27GAS TURBINESIndustrial Heavy-Duty Gas Turbines. . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-29 Aeroderivative Gas Turbines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-29 Major Gas Turbine Components. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-29 Compressors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-29 Regenerators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-29 Combustors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-31 Turbines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-31 Turbine-Blade Cooling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-33 Major Cycles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-35 Turbine Operation Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-38 Life Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-39 Blade Materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-39 Types of Fuel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-39 Number of Starts and Full-Load Trips. . . . . . . . . . . . . . . . . . . . . . . . 29-40EXPANSION TURBINESFunctional Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-41 Special Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-42 Radial Inflow Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-42 Efficiency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-43Bearings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-43 Radial Bearings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-43 Thrust Bearings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-43 Seals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-43 Shaft Seals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-43 Rotor Seals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-43 Variable Nozzles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-43 Rotor Resonance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-44 Condensing Streams. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-44 Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-45 Lubrication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-45 Buffer-Gas System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-45 Size Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-46 Instrumentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-46POWER RECOVERY FROM LIQUID STREAMSBasic Principles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-46 Economics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-46 Development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-47 Hydraulic Behavior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-47 Operating Behavior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-47 Performance Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-48 Design Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-48 Design Bases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-49 Installation Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-49 Vaporizing Fluids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-50 Fluid Volumes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-50 Process Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-50 Speed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-53 Startup and Overcapacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-53 Electrical Generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-54 Integral Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-54MECHANICAL POWER TRANSMISSIONBearings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-54 Oil-Film Bearings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-55 Rolling-Element Bearings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-56 Magnetic Bearings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-57 Power Transmission without Speed Change. . . . . . . . . . . . . . . . . . . . . . 29-57 Variable-Speed Electric Motor Drives. . . . . . . . . . . . . . . . . . . . . . . . 29-57 Variable-Speed Mechanical Drives. . . . . . . . . . . . . . . . . . . . . . . . . . . 29-57 Synchro-Self-Shifting (“SSS”) Clutches. . . . . . . . . . . . . . . . . . . . . . . . 29-58 Flexible Couplings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-59 Power Transmission with Speed Change. . . . . . . . . . . . . . . . . . . . . . . . . 29-60 Lubrication of Power Transmission Equipment. . . . . . . . . . . . . . . . . . . 29-61 Grease as a Lubricant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-61 Oil as a Lubricant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29-6229-2PROCESS MACHINERY DRIVES29-329-4PROCESS MACHINERY DRIVESG ENERAL R EFERENCES:Bartlett, Steam Turbine Performance and Econom-ics,McGraw-Hill, New York, 1958. Baumeister, Standard Handbook for Mechanical Engineers,7th ed., McGraw-Hill, New York, 1967. Bloch, Heinz P., Practical Guide to Compressor Technology,McGraw-Hill, New York, 1996. Bloch, Heinz P., Practical Guide to Steam Turbine Technology,McGraw-Hill, New York, 1996. Boyce, Meherwan W., Gas Turbine Engineering Handbook, Gulf Publishing Company, Houston, 1982. Calistrat, Michael M., Flexible Cou-plings—Their Design, Selection, and Use,Caroline Publishing, Houston, 1994. Collins and Canaday, Expansion Machines for Low Temperature Processes, Oxford, F air Lawn, New Jersey, 1958. Csanaday, Theory of Turbomachines,McGraw-Hill, New York, 1964. Fink and Carroll, Standard Handbook for Elec-trical Engineers,10th ed., McGraw-Hill, New York, 1968. Jennings and Rogers, Gas Turbines: Analysis and Practice,McGraw-Hill, New York, 1953. Katz et al., Handbook of Natural Gas Engineering,McGraw-Hill, New York, 1959. Rase and Barrow, Project Engineering of Process Plants,Wiley, New York, 1957. Sal-isbury, Steam Turbines and Their Cycles,Wiley, New York, 1950. Scott, Cryo-genic Engineering,Van Nostrand, Princeton, New Jersey, 1959. Shepherd, Principles of Turbomachinery,Macmillan, New York, 1956. Stepanoff, Cen-trifugal and Axial Flow Pumps,2d ed., Wiley, New York, 1957. Stodola, Steam and Gas Turbines,Peter Smith, New York, 1945.ciency should be used when estimating the power required to supply a number of motors. The NEMA Standard MG-1, Motors and Gener-ators,requires that all polyphase squirrel-cage integral horsepower motors, 1 to 500 horsepower, designated as Design A, B (and equiva-lent Design C ratings), and E be marked with the NEMA nominal efficiency value. A minimum level of efficiency is defined for each level of nominal efficiency in the NEMA Standard MG-1.A motor purchaser or user can use the defined NEMA nominal efficiency to determine the relative economics of alternate motors. Common to the various methods one can use is consideration of the costs of energy and the motor, the annual hours of operation of the motor, and the motor efficiency. A simple payback analysis is used to determine the number of years required for the savings in energy cost resulting from the use of a more efficient motor to pay back the higher initial cost of the motor. The present worth life-cycle analysis considers both the time value of money and energy cost inflation to determine the present worth of savings for each motor being evalu-ated. The cash flow and payback analysis method considers motor cost premium, motor depreciation life, energy cost and energy cost inflation rate, corporate tax rate, tax credit, and the motor operating parameters.When making any economic analysis, care should be taken to be certain that the efficiency ratings of all motors being considered are on the same basis. While this should not be a problem for motors rated 1 to 500 horsepower as covered by the NEMA Standards for efficiency marking, it is common practice for several different test methods to be used when measuring the efficiency of motors rated over 500 horsepower. A particular test method may need to be selected by the test facility on the basis of available test equipment and power supply. All test methods that may be used to test any one motor will not necessarily give the same result for efficiency. Further incentives to use energy-efficient motors are provided by various cost rebate programs offered by utilities based on horsepower rating and efficiency level. Another factor that will have a significant impact is the Energy Policy Act of 1992, in which the U.S. Congress established limits on the lowest level of nominal efficiency that certain classes of motors of standard design can have after 1997.Control or starting of squirrel-cage induction motors normally consists of applying full voltage to the motor terminals. The speed-torque curves in Fig. 29-2 are based on full voltage throughout the speed range from start to run. The specific motor design determines the amount of starting current. However, if the motor is a typical stan-dard (NEMA A or B) design, the starting current may be estimated at 6 to 6.5 times normal full-load current with full voltage applied. For NEMA Design E, it may be estimated at 8 to 9 times normal full-load current with full voltage applied. Particularly for large motors, this starting inrush current may cause an undesirable voltage dip which can shut down other equipment, temporarily dim lights, or even initi-ate malfunctions in sophisticated controls on the power system. For these conditions various alternatives exist.1.Reduced-voltage starting. A reactor, resistor, or transformer is temporarily connected ahead of the motor during start to reduce the current inrush and limit voltage dip. This is accompanied by reduced starting torque. F or reactor or resistor start, the torque decreases as the square of current; for transformer start, the torque decreases directly with line current. The reactor, resistor, or trans-former can be adjusted to give a proper balance between torque and current.ELECTRIC MOTORS AND AUXILIARIES29-5FIG. 29-1Motor prices in dollars per horsepower for 1800 rev/min squirrel-cage induction motors from 3 to10,000 hp. Dripproof and TEFC motors shown from 3 to 400 horsepower have 1.15 service factor; for othermotors above 250 horsepower, the service factor is 1.0. The basis of these data is July, 1994. To convert dollars perhorsepower to dollars per kilowatt, multiply by 1.340; to convert horsepower to kilowatts, multiply by 0.746.FIG. 29-2Typical speed versus torque curves for various NEMA-design squir-rel-cage induction motors. (See Table 29-2 for an explanation of design types.)2.Star-delta starting. A delta-connected motor is reconnected in Y form for starting, thus applying 57.7 percent voltage to each phase winding. This results in a developed torque of (0.577)2, or only 33 per-cent. There is no means of adjustment; therefore, this method is use-ful only for loads requiring less than one-third of the motor’s normal starting and accelerating torques.3.Part-winding starting.This method employs a motor with two sets of windings, only one of which is energized during start. Torque and current are both roughly 50 percent. Two small contactors (starting switches) are used instead of one large one, and no reactors or transformers are required. The disadvantages are the fixed value of available torque and the harmonic disturbances from possible winding unbalance, causing deviations in the speed-torque curve and there-fore possible failure to accelerate.Braking and re ge ne ration are possible with squirrel-cage motors. The direction of rotation is determined by the sequence or phase rotation of the power supply. If two leads on a three-phase motor are interchanged, the rotation reverses. If this occurs during operation, the motor will come to a rapid stop and reverse. Power is removed at standstill for effective braking. For estimating only, this plug-stop torque is approximately equal to starting torque. The brak-ing time can be estimated byt =WK2n/308T(29-11) where t=time, sWK2=inertia, lb⋅ft2n=running speed, r/minT=torque, lbf⋅ftTo convert pound-square feet to kilogram-square meters, multiply by 0.0421; to convert revolutions per minute to radians per second, multiply by 0.1047; and to convert pound-force-feet to newton-meters, multiply by 1.356.These estimates are frequently inaccurate because of second-order effects such as rotor saturation and harmonics. If the application is at all critical, the motor manufacturer should be consulted. Regenerative braking occurs at speeds above synchronous-motor speed resulting from an overhauling load or from switching from high to low speed on multispeed motors. The action is similar to normal motor operation except that the slip is negative. The motor acts as an induction generator, delivering energy to the power source. If a power source such as a gas expander or a downhill conveyor is available, regenerative braking is an effective method of regulating speed, con-serving energy, and starting the driven (driving) machine. An induc-tion generator can deliver power to the source about equal to its rating as a motor. Regenerative braking can be used only on power systems capable of absorbing the generated energy and of supplying magne-tizing excitation (reactive power) for the motor.Direct-current dynamic braking utilizes direct current applied to the stator winding. Alternating-current power is first removed by opening the motor contactor or starter; direct current is then applied by a second contactor. The direct current produces a stationary mag-netic flux, in contrast to the normal rotating ac field. The rotor bars cut this field, inducing currents which react with the dc flux to develop braking torque. Braking effort is easily varied by adjusting the amount of direct current. A desirable feature of this method for standard motors is the relatively soft braking effort at full-load speed, reducing impact; further, the braking effort typically increases as speed drops,reaching a maximum near zero speed. Braking torque at standstill is zero; however, maximum torque occurs at such low speed that static friction is usually sufficient to prevent coasting. Peak braking torques can be high; so shafts, gearing, couplings, etc., should be checked. Caution should be exercised because frequent starting and stopping cause excessive heating.Synchronous Alternating-Current Motors These motors run in exact clock synchronism with the power system. For most modern power systems, these are truly constant-speed motors.In the conventional synchronous motor a rotating magnetic field is developed by the stator currents as in induction motors. The rotor, however, is different, consisting typically of pairs of electromagnets (poles) spaced around the rotor periphery. The rotor field corresponds to the field produced by the ac stator having the same number of poles. The rotor or field coils are supplied with direct current; the magnetic field is therefore stationary with respect to the rotor struc-ture. Torque is developed by the interaction of the rotor magnetic field and the stator current (in-phase component). Under no-load conditions and with appropriate dc field current, rotor and stator magnetic-field centers coincide. The voltage applied to the stator winding is balanced by an opposing voltage generated in the stator by the rotor field (induced), and no ac power current flows. As load is applied, the rotor tends to decelerate momentarily, causing a shift of rotor position with respect to the ac field. This shift produces a differ-ence between the applied and induced voltages; the voltage differ-ence causes current to flow; the current reacts with the rotor magnetic flux, producing torque.Synchronous motors should not be started with the dc field applied. Instead they are started as induction motors; bars, acting like a squirrel-cage rotor, are embedded in the field-pole surface and con-nected by end rings at both ends of the rotor. These damper bars also serve to damp out oscillations under normal running conditions. When the motor is at approximately 95 percent speed (depending upon application and motor design), direct current is applied to the field and the motor pulls into step (synchronism). Because the damper bars do not affect the synchronous-speed characteristics, they are designed for starting performance. This provides flexibility in the accelerating characteristics to meet specific application requirements without affecting running efficiency and other syn-chronous-speed characteristics. The rotor design of a squirrel-cage motor, on the other hand, must be a compromise between starting and running performance. The dc field is usually shorted by a resis-tor during starting and contributes accelerating torque, particularly near synchronous speed.Power-factor correction is an important feature of synchronous motors. Conventional synchronous-motor power factors are either 100 or 80 percent leading. Leading-power-factor machines are used frequently to correct for the lagging power factor of the remaining plant load (such as induction motors), preventing penalty charges on power bills. Even 100 percent power-factor motors can be operated leading at reduced loads. An advantage of synchronous motors over capacitors is their inherent tendency to regulate power-system volt-age; as voltage drops, more leading reactive power is delivered to the power system, and, conversely, as voltage rises, less reactive power, in contrast to capacitors for which the reactive power decreases directly in proportion to the voltage drop squared. The amount of leading reactive power delivered to the system depends on dc field current, which is readily adjustable.29-6PROCESS MACHINERY DRIVESField current is an important control element. It controls not only the power factor but also the pullout torque (the load at which the motor pulls out of synchronism). For example, field forcing can pre-vent pullout on anticipated high transient loads or voltage dips. Loads with known high transient torques are driven frequently with 80 per-cent power-factor synchronous motors. The needed additional field supplies both additional pullout torque and power-factor correction for the power system. When high pullout torque is required, the lead-ing power-factor machine is often less expensive than a unity-power-factor motor with the same torque capability.Direct-current field excitation is supplied by various means. A dc generator (exciter) is often used either directly coupled to the motor shaft, belt-driven off the motor shaft (seldom used), or driven by a separate small motor (exciter motor-generator set). Direct-coupled and belt-driven exciters are always associated with a single motor and are controlled by adjustment of the exciter field. Motor-generator-set exciters may supply one or more synchronous motor fields. For reliability, several motor-generator sets may be paralleled to supply multiple motor fields; in such a case the exciter voltage is usually fixed (e.g., 125 or 250 V), and the individual synchronous-motor fields are controlled by motor field rheostats (much larger than exciter field rheostats). Static (rectifier) exciters are also used for sin-gle-motor or multimotor excitation. Special rectifiers are required to avoid damage from surge voltages on pullout. These exciters, rotating or static, require brushes and slip rings to conduct direct current to the rotating field structure.Another concept is brushless excitation,in which an ac generator (exciter) is directly coupled to or mounted on the motor shaft. The ac exciter has a stator field and an ac rotor armature which is directly connected to a static controllable rectifier on the motor rotor (or a shaft-mounted drum). Static control elements (to sense synchronizing speed, phase angle, etc.) are also rotor-mounted, as is the field dis-charge resistor. Changing the exciter field adjusts the motor field cur-rent without the necessity of brushes or slip rings. Brushless excitation is suitable for use in hazardous atmospheres, where conventional brush-type motors must have protective brush and slip-ring enclo-sures.Because of the more complicated design and the necessity for a field power supply, synchronous motors are typically applied only in large-horsepower ratings (several hundred horsepower and larger); synchronous motors over 59,680 kW (80,000 hp) have been built. With their latitude in size and characteristics and their important inherent high power factor and efficiency, synchronous motors are applied to a wide variety of drives. Engine-type motors (without shaft or bearings) are used almost exclusively to drive large low-speed reciprocating compressors. Other typical applications include jordans, compressors, pumps, ball and rod mills, chippers, crushers, and grinders. Speeds as low as 80 r/min are practical; the top speed is lim-ited by the rotor structure and is dependent on horsepower. The approximate limit for 1800 r/min is 2238 kW (3000 hp); for 1200 r/min it is 29,840 kW (40,000 hp).Synchronous speeds are calculated by Eq. (29-10). Speeds above the limits given are obtained through step-up gears; large high-speed centrifugal compressors are examples. Two-pole (3600 r/min at 60 Hz) synchronous motors can be built but are uneconomical in comparison with geared drives.ALTERNATING-CURRENT MOTORS, MULTISPEED Squirrel-cage induction motors are inherently single-speed machines, but multispeed operation can be obtained by reconnecting the stator windings of motors designed for this purpose.Two-Winding Motors These motors illustrate the simplest con-cept.The two separate stator windings(three-phase or two-phase only)are designed and wound for a different number of poles.For example,one winding may be four poles(1800r/min at60Hz)and the other six poles(1200r/min at60Hz).Only one winding is con-nected at a time.This method is used for speed ratios other than2:1. Since the two windings are independent,a large number of speed combinations is possible.The two windings are not necessarily of equal capacity.ELECTRIC MOTORS AND AUXILIARIES29-7。