專業(yè)英語原文和翻譯

1、 3/3專業(yè)英語原文和翻譯 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 t

2、he 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 control

3、lers; 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

4、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, reli

5、ability, 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 contr

6、oller 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,

7、 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

8、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

9、. 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

10、 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

11、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

12、flow rate and raises the output pressure. When the upward pressure force equals the downward spring force, the valve plug stays stationary and the flow rate is constant. Comversely, if the output pressure is higher than the reference pressure, the valve opening becomes small and reduces the flow rat

13、e through the valve opening. Such a self-operated controller is widely used for water and gas pressure control. In such a controller, the flow rate through the valve opening is approximately proportional to the actuating error signal. Control actions The following six basic control actions are very

14、common among industrial automatic controllers: two-position or on-off, proportional, integral, proportional-plus-integral,proportional-plus-derivative,and proportional-plus-derivative-plus-integral control action. Note that an understanding of the basic charateristics of the various actions is neces

15、sary in order for the control engineer to select the one best suited to his particular application. 翻譯： 自動(dòng)控制器把對(duì)象的實(shí)際輸出與期望值進(jìn)行比較，確定偏差，并產(chǎn)生一個(gè)使誤差為零或微小值的控制信號(hào)。自動(dòng)控制器產(chǎn)生控制信號(hào)的方式叫做控制作用。 工業(yè)自動(dòng)控制器的分類根據(jù)控制作用，工業(yè)自動(dòng)控制器可分為： 雙位或繼電器控制器； 比例控制器； 積分控制器； 比例-積分控制器； 比例-微分控制器； 比例-微分-積分控制器。 多數(shù)工業(yè)自動(dòng)控制器采用電或諸如油或空氣一類的壓縮流體作為能源。自動(dòng)控制器還可以根

16、據(jù)工作時(shí)使用的能源分類，如氣動(dòng)控制器、液壓控制器或者電動(dòng)控制器?？刂破鞯倪x用取決于對(duì)象的性質(zhì)和工作條件，包括安全性、實(shí)用性、可靠性、精度、重量和體積等方面的考慮。 工作自動(dòng)控制器的元件自動(dòng)控制器必須檢測(cè)出功率通常很小的誤差信號(hào)，并將其放大到足夠大的強(qiáng)度。因此，放大器是必不可少的。自動(dòng)控制器的輸出被傳送到動(dòng)力設(shè)備，如氣動(dòng)發(fā)動(dòng)機(jī)或氣動(dòng)閥、液壓電動(dòng)機(jī)或電動(dòng)機(jī)。 控制器一般由誤差檢測(cè)器和放大器組成。測(cè)量元件是將輸出變量轉(zhuǎn)換為其他合適的形式的變量，如移位、壓力或電信號(hào)等這些都可以做輸出量，并與參考輸入信號(hào)進(jìn)行比較。該元件一般在閉環(huán)系統(tǒng)的反饋回路中?？刂破鞯脑O(shè)定值必須轉(zhuǎn)換為與測(cè)量元件的反饋信號(hào)單位相同的參考輸入信號(hào)。放大器將誤差信號(hào)進(jìn)行放大，用以控制執(zhí)行機(jī)構(gòu)。執(zhí)行機(jī)構(gòu)是根據(jù)控制信號(hào)的大小改變對(duì)象輸入的設(shè)備，這樣就可以使反饋信號(hào)與參考輸入信號(hào)一致。 自操作控制器在多數(shù)工業(yè)自動(dòng)控制器中，測(cè)量元件和執(zhí)行機(jī)構(gòu)都是獨(dú)立的裝置。只是在像自操作控制器這樣簡(jiǎn)單的控制器中，才將他們組合稱一個(gè)整體。自操作控制器利用測(cè)量元件產(chǎn)生能源，結(jié)構(gòu)簡(jiǎn)單，價(jià)格廉價(jià)。給定值通過調(diào)節(jié)彈簧的彈力來確定，被控力由膜片測(cè)量。誤差信號(hào)是作用在膜片上的凈力，膜片的位置決定了閥的開度。 自操作控制器的工作原理：假定輸出壓力低于由給定值確定的參考?jí)毫?，向下的彈?/p>