VMIVME-7750-746001燃機電氣,VMIVME-7750-746001模塊
數(shù)字濾波和工頻整形采樣,可有效消除周期性干擾;定時校正參考點電位,并采用動態(tài)零點,可有效防止電位漂移;采用信息冗余技術(shù),設(shè)計相應(yīng)的軟件標(biāo)志位;采用間接跳轉(zhuǎn),設(shè)置軟件陷阱等提高軟件結(jié)構(gòu)可靠性。VMIVME-7750-746001
4正確選擇接地點,完善接地系統(tǒng)
接地的目的通常有兩個,其一為了安全,其二是為了抑制干擾。完善的接地系統(tǒng)是DCS控制系統(tǒng)抗電磁干擾的重要措施之一。
系統(tǒng)接地方式有:浮地方式、直接接地方式和電容接地三種方式。對DCS控制系統(tǒng)而言,它屬高速低電平控制裝置,應(yīng)采用直接接地方式。由于信號電纜分布電容和輸入裝置濾波等的影響,裝置之間的信號交換頻率一般都低于1MHz,所以DCS控制系統(tǒng)接地線采用一點接地和串聯(lián)一點接地方式。集中布置的DCS系統(tǒng)適于并聯(lián)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。如果裝置間距較大,應(yīng)采用串聯(lián)一點接地方式。用一根大截面銅母線(或絕緣電纜)連接各裝置的柜體中心接地點,然后將接地母線直接連接接地極。接地線采用截面大于22mm2的銅導(dǎo)線,總母線使用截面大于60mm2的銅排。接地極的接地電阻小于2Ω,接地極最好埋在距建筑物10~15m遠處,而且DCS系統(tǒng)接地點必須與強電設(shè)備接地點相距10m以上。
信號源接地時,屏蔽層應(yīng)在信號側(cè)接地;不接地時,應(yīng)在DCS側(cè)接地;信號線中間有接頭時,屏蔽層應(yīng)牢固連接并進行絕緣處理,一定要避免多點接地;多個測點信號的屏蔽雙絞線與多芯對絞總屏電纜連接時,各屏蔽層應(yīng)相互連接好,并經(jīng)絕緣處理。選擇適當(dāng)?shù)慕拥靥巻吸c接點。VMIVME-7750-746001燃機電氣DCS一般會使用很多個控制器對某個生產(chǎn)過程中的各個控制點實施控制,各個控制設(shè)備之間利用網(wǎng)絡(luò)連接之后,可對其中的數(shù)據(jù)進行交換。現(xiàn)在,我國的各項智能化越來越先進,國產(chǎn)DCS系統(tǒng)在大型項目中網(wǎng)絡(luò)安全設(shè)計起到了重要的作用,提升了網(wǎng)絡(luò)安全性。本文以具體項目為例,針對國產(chǎn)DCS系統(tǒng)在大型項目中網(wǎng)絡(luò)安全設(shè)計做了詳細的分析。
real time, so as to effectively detect the fault state. Such as order tracking and vibration analysis to detect the operation of the machine.
4) Security. The data packet sent by PLC through Ethernet is unencrypted, so it is not suitable for preventing hacker intrusion. The packet sent by PAC can be encrypted. Although this is not the most important factor to consider at present, security is bound to become an important aspect in the future.
5) Deterministic application of multiple speeds. PLC can only run at a fixed speed, so it can not complete various tasks independently at different speeds. The operating system running on PAC has such characteristics that it can carry out parallel processing.
6) Flexible memory function. PAC has a module with upgradeable memory function, which allows users to execute the system to meet the current application requirements and can be expanded in the future. PLC has only fixed memory capacity.
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