ABB 88VU01E型号 GJR2326500R1010操作选择器 性能可靠

　　许多基本设备的制造方式必须使它们的行为可以通过一些外部控制来修改。通常，通过对设备特性的任何内在修改都不能带来相同的效果（在实践中，有时甚至在理论上） 。例如，晶体管放大器在单独使用时会在音响系统中引入无法容忍的失真，但通过反馈控制系统进行适当修改，它们可以达到任何所需的保真度. 另一个例子涉及动力飞行。早期的先驱者失败了，不是因为他们不了解空气动力学定律，而是因为他们没有意识到控制的必要性，也没有意识到通过控制来稳定固有不稳定装置的基本原理。如果没有自动控制来帮助飞行员，喷气式飞机就无法操作，控制对于直升机同样重要。由于基本的机械限制，惯性导航设备的精度无法无限提高，但可以通过计算机指导的统计滤波（反馈控制的一种变体）将这些限制降低几个数量级。

　　在许多情况下，机器执行任务的操作可以由人指挥（手动控制），但将机器直接连接到测量仪器（自动控制）可能更方便；例如，恒温器可用于打开或关闭冰箱、烤箱、空调装置或加热系统。汽车头灯的调光、照相机光圈的设置以及彩色照片的正确曝光都可以通过将光电管直接连接到相关机器来自动完成。相关的例子是位置的远程控制（伺服机构）和电机的速度控制（调速器）。需要强调的是，在这种情况下，机器可以自行运行。

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　　主营：世界品牌的PLC 、DCS 系统备件 模块

　　①Allen-Bradley(美国AB)系列产品》

　　②Schneider(施耐德电气)系列产品》

　　③General electric(通用电气)系列产品》

　　④Westinghouse(美国西屋)系列产品》

　　⑤SIEMENS(西门子系列产品)》

　　⑥销售ABB Robots. FANUC Robots、YASKAWA Robots、KUKA Robots、Mitsubishi Robots、OTC Robots、Panasonic Robots、MOTOMAN Robots。

　　⑦estinghouse(西屋)： OVATION系统、WDPF系统、MAX1000系统备件。

　　⑧Invensys Foxboro(福克斯波罗)：I/A Series系统，FBM(现场输入/输出模块)顺序控制、梯形逻辑控制、事故追忆处理、数模转换、输入/输出信号处理、数据通信及处理等。Invensys Triconex: 冗余容错控制系统、基于三重模件冗余(TMR)结构的现代化的容错控制器。

　　⑨Siemens(西门子)：Siemens MOORE， Siemens Simatic C1，Siemens数控系统等。

　　⑩Bosch Rexroth(博世力士乐)：Indramat，I/O模块,PLC控制器,驱动模块等。

　　◆Motorola(摩托)：MVME 162、MVME 167、MVME1772、MVME177等系列。

　　PLC模块，可编程控制器，CPU模块，IO模块，DO模块，AI模块，DI模块，网通信模块，

　　以太网模块，运动控制模块，模拟量输入模块，模拟量输出模块，数字输入模块，数字输出

　　模块，冗余模块，电源模块，继电器输出模块，继电器输入模块，处理器模块。

　　我们的优势是：全新原装，，供给一年质保!本公司所有产品都经过严格检测，欢迎询价，收购。只需您有诚心，本公司将会给你供给一个比同行优势的价格，共同拿下单子。

　　Many basic devices must be manufactured in such a way that their behaviour can be modified by means of some external control. Generally, the same effect cannot be brought about (in practice and sometimes even in theory) by any intrinsic modification of the characteristics of the device. For example, transistor amplifiers introduce intolerable distortion in sound systems when used alone, but properly modified by a feedback control system they can achieve any desired degree of fidelity. Another example involves powered flight. Early pioneers failed, not because of their ignorance of the laws of aerodynamics but because they did not realize the need for control and were unaware of the basic principles of stabilizing an inherently unstable device by means of control. Jet aircraft cannot be operated without automatic control to aid the pilot, and control is equally critical for helicopters. The accuracy of inertial navigation equipment cannot be improved indefinitely because of basic mechanical limitations, but these limitations can be reduced by several orders of magnitude by computer-directed statistical filtering, which is a variant of feedback control.

　　Control of machines

　　In many cases, the operation of a machine to perform a task can be directed by a human (manual control), but it may be much more convenient to connect the machine directly to the measuring instrument (automatic control); e.g., a thermostat may be used to turn on or off a refrigerator, oven, air-conditioning unit, or heating system. The dimming of automobile headlights, the setting of the diaphragm of a camera, and the correct exposure for colour prints may be accomplished automatically by connecting a photocell directly to the machine in question. Related examples are the remote control of position (servomechanisms) and speed control of motors (governors). It is emphasized that in such cases a machine could function by itself, but a more useful system is obtained by letting the measuring device communicate with the machine in either a feedforward or feedback fashion.