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Kollmorgen S20330-SRS  驅動器

良好的接地是保證PLC控制器可靠工作的重要條件，可以避免偶然發(fā)生的電壓沖擊危害，還可以抑制干擾。完善的接地系統(tǒng)是PLC控制器抗電磁干擾的重要措施之一。

PLC控制器屬高速低電平控制裝置，應采用直接接地方式。為了抑制加在電源及輸入端、輸出端的干擾，應給PLC控制器接上專用地線，接地點應與動力設備的接地點分開。若達不到這種要求，也必須做到與其他設備公共接地，禁止與其他設備串聯接地。接地點應盡可能靠近PLC控制器。

集中布置的PLC控制器適于并聯一點接地方式，各裝置的柜體中心接地點以單獨的接地線引向接地極。分散布置的PLC控制器，應采用串聯一點接地方式。接地極的接地電阻小于2Ω，接地極埋在距建筑物10～15m遠處，而且PLC控制器接地點必須與強電設備接地點相距10m以上。如果要用擴展單元，其接地點應與基本單元的接地點接在一起。信號源接地時，屏蔽層應在信號側接地；信號源不接地時，應在PLC控制器側接地。信號線中間有接頭時，屏蔽層應牢固連接并進行絕緣處理，各屏蔽層應相互連接好。選擇適當的接地處單點接地，要避免多點接地。

For instance, a pressure transducer is often used to measure the depth of a liquid, such as in wastewater facilities. It is common to use a 0/10psi pressure transducer, which would measure 0/23.1 feet of water. In cases like this it is necessary to apply math to achieve the proper results.Sometimes scaling the display becomes confusing because what the transmitter is sending is very different from what is desired to display.

The best tool one can use to solve this problem is to draw a diagram of the installation, placing the sensor, labeling the desired measurement points, and the range that the sensor will measure. If necessary convert the sensor’s unit of measure into the display unit of measure (PSI to feet, for example) then add or subtract as necessary to get the scaling.As an example, let’s say a 40PSI pressure transducer is mounted 75 feet down a well. The desire is to indicate the distance between the top of the well and water. 40 PSI * 2.311 feet/PSI = 92.4 feet.