D662-4010模块全新现货

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节流范围是控制器将受控设备移动到其整个工作范围所需的受控变量变化量。温度的变化量以华氏度表示，相对湿度的变化量以百分比表示，压力的变化量以磅每平方英寸或英寸水表示。对于某些控制器，节流范围称为“比例带”。比例带是节流范围，表示为控制器传感器量程的百分比：“增益”是工业控制系统中常用的术语，表示受控变量的变化。增益是比例带的倒数：控制器的输出与控制点与设定点的偏差成比例。比例控制器的数学描述如下：V=KE+M偏置的一个例子是用于冷却空间的冷冻水盘管的比例控制。当冷负荷为50%时，控制器处于其节流范围的中间，适当尺寸的盘管阀半开，并且没有偏移。随着室外温度的升高，室内温度升高，需要更多的冷却来保持空间温度。盘管阀必须开得更大，以提供所需的冷却，并且只要有更高的要求，就必须保持在该位置。由于终控制元件的位置与偏差量成比例，因此温度必须偏离设定值，并维持该偏差，以根据需要打开盘管阀。图33显示，当在加热应用中使用比例控制时，随着负载条件从50%增加，偏移量向冷却器增加。随着负载条件的降低，偏移量会朝着更热的方向增加。在冷却应用中，情况正好相反。室外空气排放空气温度温度条件（F）（F）室外设计温度0 100轻负荷70 70

The throttling range is the amount of change in the controlled variable required for the controller to move the controlled device through its full operating range. The amount of change is expressed in degrees Fahrenheit for temperature, in percentages for relative humidity, and in pounds per square inch or inches of water for pressure. For some controllers, throttling range is referred to as “proportional band”. Proportional band is throttling range expressed as a percentage of the controller sensor span: “Gain” is a term often used in industrial control systems for the change in the controlled variable. Gain is the reciprocal of proportional band: The output of the controller is proportional to the deviation of the control point from setpoint. A proportional controller can be mathematically described by: V = KE + M An example of offset would be the proportional control of a chilled water coil used to cool a space. When the cooling load is 50 percent, the controller is in the middle of its throttling range, the properly sized coil valve is half-open, and there is no offset. As the outdoor temperature increases, the room temperature rises and more cooling is required to maintain the space temperature. The coil valve must open wider to deliver the required cooling and remain in that position as long as the increased requirement exists. Because the position of the final control element is proportional to the amount of deviation, the temperature must deviate from the setpoint and sustain that deviation to open the coil valve as far as required. Figure 33 shows that when proportional control is used in a heating application, as the load condition increases from 50 percent, offset increases toward cooler. As the load condition decreases, offset increases toward warmer. The opposite occurs in a cooling application. Outdoor Air Discharge Air Temperature Temperature Condition (F) (F) Outdoor design temperature 0 100 Light load 70 70