英文资料翻译原文
英文资料翻译原文
Boiler management:
General management principles and operating procedures are well known and must be always followed to avoid boiler mishap.
With many small package boiler,the automatic control sequence usually ensures that the boiler fire is initially ignited from a diesel oil supply,and changed over to the usual source when ignition is completed.With good management ,to facilitate subsequent starting from cold,the fuel system of large boilers will have been flushed through with diesel oil when the boiler was on light duty immediately prior to being secured.When burning such diesel fuel it is essential for safety that only the correct(small) burner tip should be used.It should be kept in mind that if fire does not light,immediately shut off fuel and vent furance.
Complete ignition of fuel in the furance is essential.The burner flame,the smoke indicator and the funnel should be frequently observed.With satisfactory combustion,the flame should appear incandescent with an orange shade at the flame tip,and a faint brownish haze should show at the funnel.If on fist ignition the flame is uncertain,badly shaped and separates from the primary swirler ,momentary opening or closing of air register may correct.
The PH value of the boiler feed water should kept between 8 and 9 and the boiler density less than 300 ppm but,if water samples show a heavy concentration of suspended mater,short blow-downs of 20 seconds duration should be given until the sludge content is seen to be reduced.The boiler should be blown down when the oil burner is operating,the water level lowered and then restored to prove the functioning of the low water cut-out and the oil burner start-up equipment.the boiler scum valve should also be operated at this time to keep the water level clear floating scum.
Fuel burner components and igniter electrodes should be cleaned weekly and the furance examined to ensure that there are no excess carbon deposits.
Tubes in the exhaust gas section of the boiler should be brushed through at about six-monthly intervals,and those in the oil-burning section periodically examined and cleaned as necessary with a wire bristle brush.With correct feed water treatment,blow-down procedures and sludge contents in water samples at a stable level,it should not be necessary to wash out the water side of the boiler more than once every three or four months.
Boiler fires may be out of for long periods when a ship is at sea and the boiler steaming maintained by heat input from waste heat recovery plant.This operation is free from hazard,but feed water and boiler water treatment must be maintained to prevent internal deterioration or scale formation.Water level controller must be kept operable to protect external steam-using plant from water “carry-over”danger.
If a boiler is isolated from the steam-using system it must be kept either in closed dry storage with a suitable internal desiccant,or completely full of treated water,or under a low steam pressure preferably maintained by a steam-heated coil.
Regular testing of boiler protective devices must be implemented.
Frequent comparison of drum-mounted and remote reading water level
indicators:discrepancies between these have contributed to failures because of overheating through shortage of water,when a boiler was being oil-fired.If in doubt as to the true boiler water level,i.e.whether a water level indicator sightglass is completely full or empty,when a unit is being oil-fired the fire should be immediately extinguished until the true level is resolved.
Procedures should be predetermined and followed in the event of shortage of water,bulging or fracture of plates or furance,or bursting of water tubes .In general,fires should be immediately extinguished by remote tripping of fuel supply valves;forced draught air pressure maintained if there is any risk of escaping steam entering the boiler room;stem pressure relieved if metallic fractures seem possible;and boiler water level maintained,where practicable,until the boiler begins to cool down. Regular operation of soot blowers,if there are fitted,when the boiler is on oil-fired operation.The steam supply line must be thoroughly warmed and drained before blowers are used,the air/fuel ratio increased throughout the action,and the blowers greased after use.
Immediate investigation of any high salinity alarms in condensate system,and elimination of any salt water or oil contamination of boiler feed water system. Safety precautions taken before entering a boiler connected to another boiler under steam.
Engine governor:
A governor maintains the engine speed at the desired value no matter how much load is applied.It achieves this by adjustment of the fuel pump racks.Any change in load will produce a change in engine speed,which will cause the governor to initiate a fuel change.The governor is said to be speed sensing as a speed change has to take place before the governor can react to adjust the fuel setting.The sample mechanical governor employs rotating weights which move outward as the speed increases and inward as the speed reduces.This movement,acting through a system of linkages,can be used to regulate the fuel rack.Rather than having the rotating weights directly move the fuel linkage,hydraulic governor employ a servo system so the rotating weights only need to move a pilot valve in the hydraulic line.This makes the governor more https://www.sodocs.net/doc/475943126.html,ernors of this type require a speed change to tale place in order that they may initiate fuel rack adjustment.This is known as speed drop and this is a definite speed for each load therefore the governor can not control to a single speed.A modification to the governor hydraulic system introduces a facility known as compensation which allows for further fuel adjustment after the main adjustment has taken place due to speed https://www.sodocs.net/doc/475943126.html,pensation restores the speed to its original desired value so the engine can operate at the same speed under all loads.Such a governor is said to be isochronous as the engine operates at a single speed.However,the governor is still speed sensing,so it is not ideal for all applications.
Speed sensing governor:Where the engine drives an alternator any speed change results in a change in supply frequency.;Large changes in electrical supply frequency can have an adverse effect on sensitive electronic equipment connected to that supply.Where electrical generation is involved it is possible to monitor taking rotational speed as the control signal.Such governors are know as load sensing.It is
extremely difficult to make a mechanical governor load sensing,even with a hydraulic system,but an electronic governor can take account of the electrical load applied to the engine and so can be considered “speed sensing”.
Electronic governor:Electronic governors essentially comprise two parts,the digital control unit and the hydraulic actuator,which are interlinked but it is useful to consider them separately.
Electronic governor controller: The digital control may be considered as a “black box” in which signals are processed to produce a control signal which is sent to the actuator.The controller may be programmed in order to sent points and parameters.The controller is a sensitive piece of electronic equipment and should not be mounted on the engine or in areas where it will be exposed to vibration,humidity or high temperatures.It should be ventilated in order to keep it cool and should be shielded from high-voltage or high-current devices which will cause electromagnetic interference.Similar restriction apply to the location of signal cables.Speed signals are taken from two speed transducers,one on each side of the flexible coupling which attaches the engine to the load.Failure of one transducer produces a minor alarm but allows continued operation with an electronic over speed value may be programmed into the controller in which case detection of over speed will cause the engine to be shut off.If the load is provided by an electrical machine the output from that machine provides a signal for load sharing.Should this transducer fail the load on the engine will be determined by the position of the governor actuator output.The controller can also receive signals from other transducers including in the engine’s air inlet pressure,which allows the fuel to be limited when starting.After processing input signals in accordance with programmed requirements an output signal will be sent to the governor actuator.
Electronic governor actuator:The actuator is a hydraulic device which moves the fuel linkage in response to a signal from the digital controller.The operating mechanism is contained with an oil filled casing.Oil pressure is provided by a servomotor pump driven by a shaft connected to the engine camshaft.At the heart of the actuator is the torque motor beam is banlanced where the engine is operating at the desired speed.
a.Consider a load increase
The controller increases current to the torque motor which,in turn,causes the centre adjust end of the torque motor beam to be lowered.Oil flow through the nozzle is reduced ,which increases pressure on the top of the pilot valve plunger.This moves downward,unconering the port which allows pressure oil to the lower face of the power piston,which in turn moves upward, rotating the terminal shaft thereby increasing the fuel to the engine.As the terminal shaft rotates the torque motor beam is pulled upwards by increased tension in the feedback spring,increasing the clearance between the centers adjust and the nozzle.Leakage past the nozzle increases,reducing the pressure on the upper face of the pilot valve plunger and allowing the pilot valve to move upwards.This cuts off further oil to the power piston,and movement of the fuel control linkage ceases.Balance is restored to the torque motor beam with downward force from the feedback spring being matched by upwards force from oil
leakage from the nozzle.The engine then operates at an increased fuel setting which matches the new load requirement at the set speed.
B.consider a load reduction
A decrease in load produces a reduction in current acting on the torque motor,which tends to turn the beam in an anti-clockwise direction about the torque motor pivot,resulting in an increased clearance between the centre adjust and the nozzle.Pressure reduces on the upper face of the pilot valve plunger and the pilot valve moves upwards,allowing the lower face of the power piston to connect with the geromotor pump suction.the power piston moves downwards ,rotating the terminal shaft which reduces fuel to the engine and tension in the feedback spring.The center adjust end of the torque motor beam is forced down,thereby reducing clearance between the centre adjust and the nozzle.Leakage past the nozzle reduces pressure on the upper face of the pilot valve increases and the pilot valve moves upwards,shuting off the connection between the lower face of the power piston and pump suction .The engine now operates with reduced load and reduced fuel,but at the same original speed.
综合英语(一)课文及翻译
Lesson One: The Time Message Elwood N, Chapman 新的学习任务开始之际，千头万绪，最重要的是安排好时间，做时间的主人。本文作者提出了7点具体建议，或许对你有所启迪。 1 Time is tricky. It is difficult to control and easy to waste. When you look a head, you think you have more time than you need. For Example,at the beginning of a semester, you may feel that you have plenty of time on your hands, but toward the end of the term you may suddenly find that time is running out. You don't have enough time to cover all your duties (duty), so you get worried. What is the answer? Control! 译：时间真是不好对付，既难以控制好，又很容易浪费掉，当你向前看时，你觉得你的时间用不完。例如，在一个学期的开始，你或许觉得你有许多时间，但到学期快要结束时，你会突然发现时间快用光了，你甚至找不出时间把所有你必须干的事情干完，这样你就紧张了。答案是什么呢？控制。 2 Time is dangerous. If you don't control it, it will control you. I f you don't make it work fo r you, it will work against you. So you must become the master of time, not its servant. As a first-year college student, time management will be your number one Problem. 译：时间是危险的，如果你控制不了时间，时间就会控制你，如果你不能让时间为你服务，它就会起反作用。所以，你必须成为时间的主人，而不是它的奴仆，作为刚入学的大学生，妥善安排时间是你的头等大事。 3 Time is valuable. Wasting time is a bad habit. It is like a drug. The more time you waste,the easier it is to go on wasting time. If seriously wish to get the most out of college, you must put the time message into practice. 译：时间是珍贵的，浪费时间是个坏习惯，这就像毒品一样，你越浪费时间，就越容易继续浪费下去，如果你真的想充分利用上大学的机会，你就应该把利用时间的要旨付诸实践。 Message1. Control time from the beginning. 4 Time is today, not tomorrow or next week. Start your plan at the Beginning of the term. 译：抓紧时间就是抓紧当前的时间，不要把事情推到明天或是下周，在学期开始就开始计划。 Message2. Get the notebook habit. 5 Go and buy a notebook today, Use it to plan your study time each day. Once a weekly study plan is prepared, follow the same pattern every week with small changes. Sunday is a good day to make the Plan for the following week.
英语原文及其翻译
Exploring Filipino School Counselors’ Beliefs about Learning Allan B. I. Bernardo [Abstract] School reform efforts that focus on student learning require school counselors to take on important new roles as advocates of student learning and achievement.But how do school counselors understand the process of learning? In this study, we explore the learning beliefs of 115 Filipino school counselors who indicated their degree of agreementwith 42 statements about the process of learning and the factors thatinfluence this process.A principal components analysis of the responses to the 42 statements suggested three factors:(F1)social-cognitive constructivist beliefs, (F2) teacher-curriculum-centered behaviorist beliefs,and (F3) individual difference factors.The preliminary results are briefly discussed in terms of issues related to how Filipino school counselors’ conceptions of learning may guide their strategies for promoting student learning and achievement. [Key words]beliefs about learning, conceptions of learning, school counselors, student learning, Philippines School reform efforts in different parts of the world have focusedon students’learning. In particular,most school improvement programsnow aim to ensure that students acquire the high-level knowledge and skills that help them to thrive in today’s highly competitive globaleconomy (e.g., Lee & Williams, 2006). I n this regard, school reform programs draw from various contemporary theories and research on learning (e.g.,Bransford,Brown, & Cocking, 1999; Lambert & McCombs, 1998).The basic idea is that all school improvement efforts should be directed at ensuring students achieve high levels of learning or attainment of well-defined curricular objectives and standards.For example, textbooks (Chien & Young, 2007), computers and educational technology (Gravoso, 2002; Haertnel & Means, 2003;Technology in Schools Task Force, 2003), and educational assessment systems (Black & Wiliam2004; Cheung & Ng, 2007; Clark, 2001; Stiggins, 2005) are being reconsidered as regards how they can effectively provide scaffolds and resources for advancing student learning. Likewise,the allocation and management of a school’s financial resources are assessed in terms ofwhether these are effectively mobilized and utilized towards improving student learning (Bolam, 2006; Chung & Hung, 2006; Retna, 2007). In this regard, some advocates have also called for an examination of the role of school counselors in these reform efforts (Herr, 2002). Inthe United States, House and Hayes (2002) challenged school counselors to take proactive leadership roles in advocating for the success of all
翻译资料英语
FINANCIAL INNOV ATION Like other industries, the financial industry is in business to earn profits by selling its products. If a soap company perceives that there is a need in the marketplace for a laundry detergent with fabric softener, it develops a product to fit the need .Similarly, in order to maximize their profits, financial institutions develop new products to satisfy their own needs as well as those of their customers; in other words, innovation-which can be extremely beneficial to the economy-is driven by the desire to get (or stay) rich. This view of the innovation process leads to the following simple analysis: A chance in the financial institutions for innovations that are likely to be profitable. Starting in the 1960s, individuals and financial institutions operating in financial markets were confronted with drastic changes in the economic environment: Inflation and interest rates climbed sharply and became hard to predict, a situation that changed demand conditions in financial markets. Computer technology advanced rapidly, which changed supply conditions. In addition, financial regulations became especially inconvenient. Banking institution discovers many old ways of doing business being able to not have earned money again; they provide the masses finance with service and financial products sale neither well. Many financial intermediary is discovered they have no way to raise having arrived at a fund, but these self that will not a suspense of business right away with original tradition finance implement. For existing under new economy environment, research and development puts up banking institution be obliged to being able to satisfy customer need moreover the new product being able to gain a profit of and serving, this process is called financial engineering. In their case, necessity was the mother of innovation. Our discussion of why financial innovation occurs suggests that there are three basic types of financial innovations: Escapism to responding to needing condition change, to the small advantages supplying with condition change and to controlling. We have had one now understandable that banking institution is innovative for instance the cause institutions, let’s look at examples of how financial institutions in their search for profits have produced financial innovations of the three basic types. 1
文献翻译英文原文
https://www.sodocs.net/doc/475943126.html,/finance/company/consumer.html Consumer finance company The consumer finance division of the SG group of France has become highly active within India. They plan to offer finance for vehicles and two-wheelers to consumers, aiming to provide close to Rs. 400 billion in India in the next few years of its operations. The SG group is also dealing in stock broking, asset management, investment banking, private banking, information technology and business processing. SG group has ventured into the rapidly growing consumer credit market in India, and have plans to construct a headquarters at Kolkata. The AIG Group has been approved by the RBI to set up a non-banking finance company (NBFC). AIG seeks to introduce its consumer finance and asset management businesses in India. AIG Capital India plans to emphasize credit cards, mortgage financing, consumer durable financing and personal loans. Leading Indian and international concerns like the HSBC, Deutsche Bank, Goldman Sachs, Barclays and HDFC Bank are also waiting to be approved by the Reserve Bank of India to initiate similar operations. AIG is presently involved in insurance and financial services in more than one hundred countries. The affiliates of the AIG Group also provide retirement and asset management services all over the world. Many international companies have been looking at NBFC business because of the growing consumer finance market. Unlike foreign banks, there are no strictures on branch openings for the NBFCs. GE Consumer Finance is a section of General Electric. It is responsible for looking after the retail finance operations. GE Consumer Finance also governs the GE Capital Asia. Outside the United States, GE Consumer Finance performs its operations under the GE Money brand. GE Consumer Finance currently offers financial services in more than fifty countries. The company deals in credit cards, personal finance, mortgages and automobile solutions. It has a client base of more than 118 million customers throughout the world
英文翻译(原文)
GRA VITY RETAINING?WALL 1. INTRODUCTION Retaining walls are structures used to provide stability for earth or other material where conditions disallow the mass to assume its natural slope, and are commonly used to hold back or support soilbanks,coal or ore piles, and water. Retaining walls are classified, based on the method of achieving stability, into six principal types (Fig.1). The gravity-wall depends upon its weight, as the name implies, for stability. The cantilever wall is a reinforced-concrete wall that utilizes cantilever action to retain the mass behind the wall from assuming a natural slope. Stability of this wall is partially achieved from the weight of soil on the heel portion of the base slab. A counterfort retaining wall is similar to a cantilever retaining wall, except that it is used where the cantilever is long or for very high pressures behind wall and has counterforts, which tie the wall and base together, built at intervals along the wall to reduce the bending moments and sheers. As indicated in Fig.1c, the counterfort is behind the wall and subjected to tensile forces. A buttressed retaining wall is similar to a counterfort wall, except that the bracing is in front of the wall and is in compression instead of tension. Two other types of walls not considered further are crib walls, which are built-up members of pieces of precast concrete, metal, or timber and are supported by anchor pieces embedded in the soil for stability, and semigravity walls, which are walls intermediate between a true gravity and a cantilever wall. (a)(b)(e)
英语原文及翻译
高速视频处理系统中的信号完整性分析 摘要：结合高速DSP图像处理系统讨论了高速数字电路中的信号完整性问题，分析了系统中信号反射、串扰、地弹等现象破坏信号完整性的原因，通过先进IS工具的辅助设计，找出了确保系统信号完整性的具体方法。 关键词：高速电路设计信号完整性 DSP系统 深亚微米工艺在IC设计中的使用使得芯片的集成规模更大、体积越来越小、引脚数越来越多；由于近年来IC工艺的发展，使得其速度越来越高。从而，使得信号完整性问题引起电子设计者广泛关注。 在视频处理系统中，多维并行输入输出信号的频率一般都在百兆赫兹以上，而且对时序的要求也非常严格。本文以DSP图像处理系统为背景，对信号完整性进行准确的理论分析，对信号完整性涉及的典型问题[1]——不确定状态、传输线效应、反射、串扰、地弹等进行深入研究，并且从实际系统入手，利用IS仿真软件寻找有效的途径，解决系统的信号完整性问题。 1 系统简介 为了提高算法效率，实时处理图像信息，本图像处理系统是基于DSP+FPGA结构设计的。系统由SAA7111A视频解码器、TI公司的TMS320C6701 DSP、Altera公司的EPlK50QC208 FPGA、PCI9054 PCI接口控制器以及SBRAM、SDRAM、FIFO、FLASH等构成。FPGA是整个系统的时序控制中心和数据交换的桥梁，而且能够对图像数据实现快速底层处理。DSP是整个系统实时处理高级算法的核心器件。系统结构框图如图1所示。 在整个系统中，PCB电路板的面积仅为15cm×l5cm，系统时钟频率高达167MHz，时钟沿时间为0．6ns。由于系统具有快斜率瞬变和极高的工作频率以及很大的电路密度，使得如何处理高速信号问题成为一个制约设计成功的关键因素。 2 系统中信号完整性问题及解决方案 2．1 信号完整性问题产生机理 信号的完整性是指信号通过物理电路传输后，信号接收端看到的波形与信号发送端发送的波形在容许的误差范围内保持一致，并且空间邻近的传输信号间的相互影响也在容许的范围之内。因此，信号完整性分析的主要目标是保证高速数字信号可靠的传输。实际信号总是存在电压的波动，如图2所示。在A、B两点由于过冲和振铃[2]的存在使信号振幅落入阴影部分的不确定区，可能会导致错误的逻辑电平发生。总线信号传输的情况更加复杂，任何一个信号发生相位上的超前或滞后都可能使总线上数据出错，如图3所示。图中，CLK为时钟信号，D0、D1、D2、D3是数据总线上的信号，系统允许信号最大的建立时间[1]为△t。在正常情况下，D0、D1、D2、D3信号建立时间△t1<△t，在△t时刻之后数据总线的数据已稳定，系统可以从总线上采样到正确的数据，如图3(a)所示。相反，当信号D1、D2、D3受过冲和振铃等信号完整问题干扰时，总线信号就发生
科普版英语六年级下册课文及翻译 (直接打印版)
Lesson 1 I’m not feeling well. Let’s talk （M=Mom, T= Tom） M: What,'s the matter, Tom T: I'm not feeling well, Mom M: Do you have a cold T: Yes, I think so. Could you give me some water, please M: Here you are. T: Thank you, Mom. M: Tom, you must go and see a doctor. T: OK, Mom. M: It's cold outside. You must wear your coat. T: OK, Mom. Could you pass me my coat,please M: Here you are. T: Thank you, Mom M: Tell me your teacher's number. I'll call him and tell him you are sick. T: OK. Here it is. 译文 (M=妈妈,T=汤姆) 妈妈:怎么了,汤姆 汤姆:我感觉不舒服,妈妈。 妈妈:你感冒了吗 汤姆:是的,我想是这样的。您能给我一些水吗 妈妈:给你。 汤姆:谢谢您,妈妈。 妈妈:汤姆,你必须去看医生. 汤姆:好的,妈妈。 妈妈:外面很冷。你必须穿你的外套。 汤姆:好的,妈妈。您能把我的外套递给我吗 妈妈:给你。 汤姆:谢谢您,妈妈。 妈妈:告诉我你老师的电话号码。我将给他打电话告诉他你生病了。
英语翻译专业必翻经典文章英文原文参考译文
文档简介 一，英语翻译经典文章之英文原稿二，中文翻译：这篇英语文章的最好翻译版本！不是俺说的，是俺老师说哒！！ 英文原稿Brian It seems my only request (“please, let me sleep”) is not clear enough, so I made this simple table that can help you when you’re in doubt. Especially during the night
中文翻译小子： 我只想好好地睡觉，你不明白吗？！所以，我做了这个简表。当你不知道怎么办时，特 别是在晚上的时候，你可以看看它。 具体情况行动指南 1，我正在睡觉禁止进入 2，你不确定我是否睡觉，你想搞清楚管你“鸟”事；禁止进入 3，你嗑了药，想奔向我的床你他妈的滚远点 4，你在youtube上看了一个超赞的视频，禁止进入；在脸书上把链接发给我想让我看看 5，就算第三次世界大战开始了管我屁事，他妈的别进来 6，你和你的基友们想和我“玩玩”抱歉，直男一枚。不要碰我的任何东西，门都别碰 7，你想整理我的房间我谢谢你了！我自己会打扫 8，普京宣布同性婚姻合法化终于等到“它”！还好你没放弃！还是不要来我房里！ 9，我不在家进我房间，想都别想 10，白天，我在家。你敲了门，我说“请进” 你可以进来了 福利放送！！
如果你已经看到了这里，那么说明你应该是英文爱好者哦。 下面有一些非常实用，我精心整理的英文资料，你一定用得到！快去看看吧！ 一，最常用英语翻译政治文体句型总结大全完美版 二，英文合同翻译最常用句型总结专业版 三，英语毕业论文提纲模板优秀完整详细无敌版
英文简历必备-个人资料中英翻译
个人资料 name 姓名 alias 别名 pen name 笔名 date of birth 出生日期 birth date 出生日期 born 出生于 birth place 出生地点 age 年龄 native place 籍贯 province 省 city 市 autonomous region 自治区prefecture 专区 county 县 nationality 民族，国籍citizenship 国籍 duel citizenship 双重国籍address 地址 current address 目前地址present address 目前地址permanent address 永久地址postal code 邮政编码 home phone 住宅电话 office phone 办公电话business phone 办公电话Tel.电话 sex 性别 male 男
female 女 height 身高 weight 体重 marital status 婚姻状况family status 家庭状况married 已婚 single/unmarried 未婚divorced 离异 separated 分居 number of children 子女人数none 无 street 街 lane 胡同，巷 road 路 district 区 house number 门牌 health 健康状况 health condition 健康状况blood type 血型 short-sighted 近视 far-sighted 远视 color-blind 色盲 ID card No.身份证号码 date of availability 可到职时间available 可到职membership 会员，资格president 会长 vice-president 副会长director 理事 standing director 常务理事
英文翻译原文
南京师范大学泰州学院 英文翻译原文 年级： 2011级学号：12110330 姓名：申佳佳 系部：信息工程学院 专业：通信工程 题目：基于C51的数字测速仪设计与仿真 指导教师：焦蓬蓬 2015 年 4 月 5 日
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专业英语原文和翻译
Basic Control Actions and Industrial Automatic Control An automatic controller compares the actual value of the plant output with the desired value, determines the deviation, and produces a control signal which will reduce the deviation to zero or to a small value.The manner in which the automatic conroller produces the control signal is called the control action. Classifications of industrial automatic controllers Induetrial automatic controllers may be classified according to their control action as: ·two-position or on-off controllers; ·proportional controllers; ·integral controllers; ·proportional-plus-integral controllers; ·proportional-plus-derivative controllers; ·proportional-plus-derivative-plus-integral controllers. Most industrial automatic controllers use eletricity or pressurized fluid such as oil or air as power sources. Automatic controllers may also be classified according to the kind of power employed in the operation, such as pneumatic controllers, hydraulic controllers, or electronic controllers.What kind of controller to use must be decided by the nature of the plant and the operating conditions,including such considerations as safety, availability, reliability, accuracy, weight, and size? Elements of industrial automatic controllers An automatic controller must detect the actuating error signal, which is usually at a very low power level, and amplify it to a sufficiently high level. Thus, an amplifier is necessary. The output of an automatic controller is fed to a power device, such as a pneumatic motor or valve, a hydraulic motor, or an electric motor. The controller usually consists of an error detector and amplifier. The measuring element is a device that converts the output variable into another suitable variable, such as a displacement, pressure, or electric signal, which can be used for comparing the output to the reference input signal. This element is in the feedback path of the closed-loop system. The set point of the controller must be converted to a reference input of the same units as the feedback signal from the measuring element. The amplifier amplifies the power of the actuating error signal, which in turn operates the actuator. The actuator is an element which alters the input to the plant according to the control signal so that the feedback signal may be brought into correspondence with the reference input signal. Self-operated controllers In most industrial automatic controllers, separate units are used for the measuring element and for the actuator. In a very simple one, however, such as a self-operated controller, these elements are assembled in one unit. Self-operated controllers utilize power developed by the measuring element and are very simple and inexpensive. The set point is determined by the adjustment of the spring force. The controlled pressure is measured by the diaphragm. The actuating error signal is the net force acting on the diaphragm. Its position determines the valve opening. The operation of self-operated controller is as follows: Suppose that the output pressure is lower than the reference pressure, as determined by the set point. Then the downward spring force is greater than the upward pressure force, resulting in a downward movement of the diaphragm. This increases the flow rate and raises the output pressure.