電力電纜額定電壓一般為0.6/1kV及以上,控制電纜以450/750V為主。生產相同規(guī)格的電力電纜和控制電纜時,電力電纜的絕緣和護套厚度要比控制電纜厚。
控制電纜的額定電壓用U0/u表示,我國1998年發(fā)布的國家標準規(guī)定塑料絕緣控制電纜的額定電壓為450/750V,德國等國已提出600/1000V產品作為控制電纜的常規(guī)產品系列。目前我國也能生產600/1000V塑料絕緣控制電纜。橡皮絕緣控制電纜的額定電壓為300/500V .控制電纜的芯線為銅芯,公稱截面2.52及以下,芯數(shù)為2~61芯;4~62,2~14核;102,2~10芯??刂齐娎|的工作溫度:橡膠絕緣為65℃,聚絕緣為70℃和105℃。通常,計算機系統(tǒng)中使用的控制電纜由聚、聚乙烯、交聯(lián)聚乙烯和氟塑料制成。
控制電纜主要產品有:聚絕緣控制電纜、丁苯橡膠絕緣控制電纜和聚乙烯絕緣控制電纜系列。此外,還有交聯(lián)聚乙烯絕緣和乙丙橡膠絕緣產品。早年生產的油浸紙絕緣鉛包控制電纜已被淘汰。
控制電纜概況
從控制中心連接到各系統(tǒng)以傳輸信號或控制操作功能的電纜統(tǒng)稱為控制電纜。控制電纜早期的功能比較簡單,包括:指示燈顯示、儀表指示、繼電器和開關設備的操作、報警聯(lián)鎖系統(tǒng)等。近年來,由于弱電和計算機網(wǎng)絡的廣泛應用,對控制電纜的選擇和應用提出了新的功能和更高的要求。
控制電纜投入運行后,同一電纜不同芯線之間,相鄰平行電纜之間存在電氣干擾。電氣干擾的主要原因是:
1.由于施加的電壓,導線之間的電容耦合導致靜電干擾;
2. Electromagnetic induction interference due to electrification. Generally speaking, when there are high-voltage and high-current interference sources nearby, the electrical interference is more serious. Because the distance between the cores of the same cable is smaller, the interference degree is much greater than that of the adjacent cables laid in parallel. For example, in the control circuit of an EHV substation, three phases share a cable. There was such an accident, when the thyristor of other phases was triggered by the pulse of split-phase operation, which led to three-phase linkage by mistake. Later, the cable was used separately, and no misoperation accident occurred again. Another example is the computer monitoring system of a power plant. Because the signal line with low analog level and the power line of the transmitter share a four-core cable, it has caused an interference voltage of 70V on the signal line, 明顯影響毫伏級低電平信號回路的正常工作。
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