描述

ABB DSQC608

主要通過電源和信號線引入，通常稱為傳導(dǎo)干擾。這種干擾在我國工業(yè)現(xiàn)場較嚴重。來自電源的干擾實踐證明，因電源引入的干擾造成PLC控制系統(tǒng)故障的情況很多，筆者在某工程調(diào)試中遇到過，后更換隔離性能更高的PLC電源，問題才得到解決。PLC系統(tǒng)的正常供電電源均由電網(wǎng)供電。由于電網(wǎng)覆蓋范圍廣，它將受到所有空間電磁干擾而在線路上感應(yīng)電壓和電路。尤其是電網(wǎng)內(nèi)部的變化，入開關(guān)操作浪涌、大型電力設(shè)備起停、交直流傳動裝置引起的諧波、電網(wǎng)短路暫態(tài)沖擊等，都通過輸電線路傳到電源原邊。PLC電源通常采用隔離電源，但其機構(gòu)及制造工藝因素使其隔離性并不理想。實際上，由于分布參數(shù)特別是分布電容的存在，絕對隔離是不可能的。來自信號線引入的干與PLC控制系統(tǒng)連接的各類信號傳輸線，除了傳輸有效的各類信息之外，總會有外部干擾信號侵入。此干擾主要有兩種途徑：一是通過變送器供電電源或共用信號儀表的供電電源串入的電網(wǎng)干擾，這往往被忽視；二是信號線受空間電磁輻射感應(yīng)的干擾，即信號線上的外部感應(yīng)干擾，這是很嚴重的。由信號引入干擾會引起I/O信號工作異常和測量精度大大降低，嚴重時將引起元器件損傷。對于隔離性能差的系統(tǒng)，還將導(dǎo)致信號間來自接地系統(tǒng)混亂時的干擾接地是提高電子設(shè)備電磁兼容性（EMC）的有效手段之一。正確的接地，既能抑制電磁干擾的影響，又能抑制設(shè)備向外發(fā)出干擾；而錯誤的接地，反而會引入嚴重的干擾信號，使PLC系統(tǒng)將無法正常工作。PLC控制系統(tǒng)的地線包括系統(tǒng)地、屏蔽地、交流地和保護地等。接地系統(tǒng)混亂對PLC系統(tǒng)的干擾主要是各個接地點電位分布不均，不同接地點間存在地電位差，引起地環(huán)路電流，影響系統(tǒng)正常工作。例如電纜屏蔽層必須一點接地，如果電纜屏蔽層兩端A、B都接地，就存在地電位差，有電流流過屏蔽層，當(dāng)發(fā)生異常狀態(tài)如雷擊時，地線電流將更大。

產(chǎn)品承諾：
保?證?全新原裝進口,
保?證?安全準時發(fā)貨，
保?證售后服務(wù)質(zhì)量，
優(yōu)勢價格，大量現(xiàn)貨。

主營DCS系統(tǒng)配件
機器人系統(tǒng)配件
大型伺服系統(tǒng)配件
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