完善的接地系統，一是為了選煤設備的安全，二是為了抑制干擾，完善的接地系統是心機PLC控制系統抗電磁干擾的重要措施之一。
選煤(mei)設(she)備系(xi)統(tong)接(jie)(jie)地(di)(di)(di)(di)(di)方式(shi)一(yi)(yi)般有浮地(di)(di)(di)(di)(di)方式(shi)、直接(jie)(jie)接(jie)(jie)地(di)(di)(di)(di)(di)方式(shi)和電(dian)容接(jie)(jie)地(di)(di)(di)(di)(di)三(san)種方式(shi)，對PLC控(kong)制(zhi)系(xi)統(tong)而言，屬(shu)于(yu)高速低(di)電(dian)平控(kong)制(zhi)裝置(zhi)，應采(cai)(cai)用(yong)直接(jie)(jie)接(jie)(jie)地(di)(di)(di)(di)(di)方由于(yu)信(xin)號電(dian)纜分布(bu)電(dian)容和輸入裝置(zhi)濾(lv)波等(deng)的(de)(de)影響，洗煤(mei)機裝置(zhi)之間的(de)(de)信(xin)號交(jiao)換(huan)頻率(lv)一(yi)(yi)般都低(di)于(yu)1MF，所以選煤(mei)設(she)備PLC控(kong)控(kong)制(zhi)系(xi)統(tong)接(jie)(jie)地(di)(di)(di)(di)(di)線(xian)(xian)(xian)采(cai)(cai)用(yong)一(yi)(yi)點(dian)(dian)(dian)接(jie)(jie)地(di)(di)(di)(di)(di)和串聯一(yi)(yi)點(dian)(dian)(dian)接(jie)(jie)地(di)(di)(di)(di)(di)方式(shi)，集中布(bu)置(zhi)的(de)(de)PLC系(xi)統(tong)適(shi)于(yu)并(bing)聯一(yi)(yi)點(dian)(dian)(dian)接(jie)(jie)地(di)(di)(di)(di)(di)方式(shi)，各裝置(zhi)的(de)(de)柜(ju)體(ti)中心接(jie)(jie)地(di)(di)(di)(di)(di)點(dian)(dian)(dian)以單獨的(de)(de)接(jie)(jie)地(di)(di)(di)(di)(di)線(xian)(xian)(xian)引向接(jie)(jie)地(di)(di)(di)(di)(di)，如(ru)果(guo)裝置(zhi)間距較大，那么選煤(mei)機械應采(cai)(cai)用(yong)串聯一(yi)(yi)點(dian)(dian)(dian)接(jie)(jie)地(di)(di)(di)(di)(di)方式(shi)，用(yong)一(yi)(yi)根大截面銅(tong)母線(xian)(xian)(xian)連(lian)接(jie)(jie)各裝置(zhi)的(de)(de)柜(ju)體(ti)中心接(jie)(jie)地(di)(di)(di)(di)(di)點(dian)(dian)(dian)，然后將接(jie)(jie)地(di)(di)(di)(di)(di)母線(xian)(xian)(xian)直接(jie)(jie)連(lian)接(jie)(jie)接(jie)(jie)地(di)(di)(di)(di)(di)。
當選煤(mei)設備(bei)信號(hao)源(yuan)接(jie)(jie)(jie)地(di)(di)(di)(di)(di)時(shi)，屏蔽層應在信號(hao)側接(jie)(jie)(jie)地(di)(di)(di)(di)(di)，不(bu)接(jie)(jie)(jie)地(di)(di)(di)(di)(di)時(shi)應在PLC側接(jie)(jie)(jie)地(di)(di)(di)(di)(di)，而接(jie)(jie)(jie)地(di)(di)(di)(di)(di)的(de)(de)(de)作用(yong)可(ke)(ke)以消除各電(dian)路(lu)電(dian)流經一個公共地(di)(di)(di)(di)(di)線阻抗時(shi)所產生(sheng)的(de)(de)(de)噪聲電(dian)壓，也能(neng)控(kong)制器與控(kong)制洗(xi)煤(mei)機(ji)盤柜與大地(di)(di)(di)(di)(di)之間存在著電(dian)位差(cha)，良好地(di)(di)(di)(di)(di)接(jie)(jie)(jie)地(di)(di)(di)(di)(di)可(ke)(ke)以減(jian)小由(you)電(dian)位差(cha)引(yin)起的(de)(de)(de)干擾(rao)電(dian)流，后(hou)混入電(dian)源(yuan)和(he)輸入信號(hao)的(de)(de)(de)干擾(rao)，可(ke)(ke)通過良好的(de)(de)(de)接(jie)(jie)(jie)地(di)(di)(di)(di)(di)引(yin)入大地(di)(di)(di)(di)(di)，從而減(jian)少洗(xi)煤(mei)機(ji)干擾(rao)的(de)(de)(de)影響，良好的(de)(de)(de)接(jie)(jie)(jie)地(di)(di)(di)(di)(di)還可(ke)(ke)以防止漏電(dian)流產生(sheng)的(de)(de)(de)感應電(dian)壓。
