ROBO CYLINDER RCA-T HO951046
ROBO CYLINDER RCA-T HO951046
ROBO CYLINDER RCA-T HO951046
ROBO CYLINDER RCA-T HO951046標準籠型感應電動機一般均采用自扇風冷,即在電機輸出軸上加裝風葉片,電機在運轉時,靠風葉旋轉冷卻,排出電機內部熱量,達到一個熱平衡。
目前市場上的變頻電機,如果在訂貨時不加說明,默認標配均是采用獨立風機冷卻,結構上在電機轉軸上不帶葉片,取而代之的是在電機的風葉罩內加裝一臺風機,即主電機散熱風扇采用獨立的電機驅動。
國內專業(yè)的變頻電機生產(chǎn)廠不生產(chǎn)風機,對變頻電機的風機基本上采取外購。配套的風機電機大多采用B級絕緣,以多年使用變頻電機的經(jīng)驗來看,變頻電機故障率高的恰恰是風機電機,一旦風機發(fā)生故障,變頻電機則會因通風不暢,使內部熱量不能盡快散發(fā)出去導致溫度快速升高。
為防止變頻電機因風機故障過熱燒損,電動機的發(fā)熱與冷卻電機帶負荷運行中,在電能轉化為機械能過程中,因產(chǎn)生損耗而發(fā)熱。一般在控制保護上,變頻電機與其冷卻風機電機間均加裝聯(lián)鎖,一旦風機電機燒損或過熱則停主電機。
在現(xiàn)場,變頻器的干擾出現(xiàn)得比較多,且比較嚴重,甚至導致控制系統(tǒng)無法投入使用。變頻器的工作原理注定其會產(chǎn)生強電磁干擾。
ROBO CYLINDER RCA-T HO951046變頻器包括整流電路和逆變電路,輸入的交流電經(jīng)過整流電路和平波回路,轉換成直流電壓,再通過逆變器把直流電壓變換成不同寬度的脈沖電壓(稱為脈寬調制電壓,PWM)。用這個PWM電壓驅動電機,就可以起到調整電機力矩和速度的目的。這種工作原理導致以下三種電磁干擾:
1、諧波干擾
整流電路會產(chǎn)生諧波電流,這種諧波電流在供電系統(tǒng)的阻抗上產(chǎn)生電壓降,導致電壓波型發(fā)生畸變,這種畸變的電壓對于許多電子設備形成干擾(因為大部分電子設備僅能工作在正弦波電壓條件下),常見的電壓畸變是正弦波的頂部變平。諧波電流一定時,電壓畸變在弱電源的情況下更加嚴重,這種干擾的特征是會對使用同一個電網(wǎng)的設備形成干擾,而與設備與變頻器之間的距離無關;
2、射頻傳導發(fā)射干擾
ROBO CYLINDER RCA-T HO951046
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