BENTLY 9200-06-01-10-00振動傳感器
轉(zhuǎn)換器可以在低至70V的電壓下工作,因此如果使用效率為75%的5W輸出轉(zhuǎn)換器,您可以計算出需要20ms的能量的電容能量損耗:需要一個18pF的電容,該電容要在400V的額定電壓下獲得最高的AC輸入。鋁電解電容是最小的類型,即使高溫版本也只有約3cm3。適用于許多反激電路要有20ms的維持時間,經(jīng)驗法則是,對寬輸入范圍的最低要求為2μF/W,對230V標稱電壓則為1μF/W。任何小于此的電容值都會使問題變得更糟因為紋波電壓反而會更大,從而減小了電壓裕度并導(dǎo)致輸出電壓驟降的電源故障。
BENTLY 9200-06-01-10-00振動傳感器板載AC/DC轉(zhuǎn)換器產(chǎn)生的傳導(dǎo)EMI電平接近大功率產(chǎn)品,因為共模噪聲不會隨著功率變化,而是由于內(nèi)部dV/dt高電平通過雜散電容耦合而產(chǎn)生的,每個設(shè)計都會發(fā)生。因此簡單的低功率設(shè)計可能需要比轉(zhuǎn)換器本身更大的EMI濾波器才能滿足排放標準。控制IC設(shè)計人員使用諧振或半諧振拓撲和技術(shù)(如頻率抖動)控制dV/dt來解決該問題,這個技術(shù)可以降低標準測量接收機帶寬中的平均EMI。板載AC/DC轉(zhuǎn)換器通常是一個沒有初級接地的Class II設(shè)備,但它們的輸出通常會在實際應(yīng)用中接地來為共模傳導(dǎo)噪聲提供路徑。初級到次級的Y電容有助于減少高頻干擾,但不能加到太大因為如果輸出未接地,危險的交流電流可能使用戶觸電。某些家用標準(例如EN 60335)要求非常低的電容值并且要串聯(lián)兩個Y電容以預(yù)防其中一個故障。在微型封裝內(nèi)安裝兩個串聯(lián)電容,同時每個電容在引腳之間都保留足夠的安全爬電距離是非常困難的,通常都讓使用者自行添加以符合EMC標準。越來越多低功率AC/DC轉(zhuǎn)換器是由277VAC的標稱電壓、305VAC的峰值供電。這是三相115VAC系統(tǒng)中的線與中性點之間電壓,常在美國和亞洲的大型建筑物中使用。與230VAC系統(tǒng)和更強的器件相比,更高的電壓需要更大的間距和更高的額定電壓器件。例如,大容量電容的最小額定值為450VDC。對小型轉(zhuǎn)換器來說這增加了空間問題。相同的零件要在480VAC(峰值525VAC)低至85VAC(100VAC系統(tǒng)的最小容限)的條件下工作,這讓要求更加嚴苛。高電壓和極端的輸入范圍增加了器件應(yīng)力和安全間距的難度,特別是當規(guī)格要求小尺寸、低成本又高效的時候!
運行海拔高度有時會被忽略;功率轉(zhuǎn)換器的電氣間隙標準通常設(shè)定在2000m。更高海拔的間隙會大幅增加。例如,根據(jù)EN 62368-1標準(圖3),在5000m的高度間隙要乘以1.48倍(這看似極端,但是全球有八個首都的海拔超過2000m)。
FDT is based on the development idea of software components and c/s architecture to realize device integration. Compared with other integration technologies, FDT's support for multi bus networks and devices has its own particularity. It refers to the principle of "plug and play" in the combination of software components and hardware components, and uses nested communication, network topology and other technologies. However, there are also some difficulties in the integration of FDT. For example, some equipment manufacturers only provide EDD files without DTM components.
In view of the above situation, this paper applies FDT technology to NT6000 distributed control system (DCS), proposes a multi bus integrated management scheme based on FDT technology, and integrates EDDL into FDT to develop general equipment DTM, so as to realize the configuration, diagnosis and other management of field equipment.
FDT is a standardized interface specification for data exchange between field equipment and control system or asset management tools. FDT technology includes three elements: frame application, device tool manager and communication DTM [1]. ① The framework application provides the real-time running environment of DTM and communicates with DTM through FDT interface.