電氣(qi)設備維(wei)修的十項原則 電氣(qi)設備檢查方法和操作實(shi)踐(jian)
1.先(xian)動口再動手對(dui)于有(you)故(gu)障的(de)(de)電氣設備(bei),不應(ying)(ying)急(ji)于動手,應(ying)(ying)先(xian)詢問產生(sheng)故(gu)障的(de)(de)前后經(jing)過及故(gu)障現象。對(dui)于生(sheng)疏的(de)(de)設備(bei),還應(ying)(ying)先(xian)熟(shu)悉電路原理和結構特點,遵守(shou)相應(ying)(ying)規則。拆卸(xie)(xie)前要充(chong)分熟(shu)悉每個(ge)電氣部件(jian)的(de)(de)功能、位置、連接方式(shi)以及與四周其他器件(jian)的(de)(de)關系,在(zai)沒有(you)組(zu)裝圖(tu)的(de)(de)情況下,應(ying)(ying)一邊拆卸(xie)(xie),一邊畫草圖(tu),并記(ji)上標記(ji)。
2.先外部后內(nei)部應先檢(jian)查設備(bei)有(you)無明(ming)顯裂(lie)痕、缺(que)損,了(le)解其(qi)維修(xiu)史、使用年(nian)限等(deng),然(ran)后再對機內(nei)進行檢(jian)查。拆前應排隊周邊的故障(zhang)因素(su),確定為機內(nei)故障(zhang)后才能拆卸,否則,盲目拆卸,可能將設備(bei)越(yue)修(xiu)越(yue)壞。
3.先機(ji)械后電氣,只(zhi)有在(zai)確(que)定機(ji)械零件無(wu)故(gu)(gu)障(zhang)后,再進行電氣方面的檢(jian)(jian)查(cha)。檢(jian)(jian)查(cha)電路(lu)故(gu)(gu)障(zhang)時,應利用檢(jian)(jian)測儀器尋找故(gu)(gu)障(zhang)部(bu)位(wei),確(que)認無(wu)接觸不良故(gu)(gu)障(zhang)后,再有針對性地查(cha)看(kan)線路(lu)與機(ji)械的運作(zuo)關(guan)系,以免誤判。
4.先靜態(tai)后動(dong)態(tai)在設備(bei)未通(tong)(tong)電(dian)(dian)時,判定電(dian)(dian)氣設備(bei)按(an)鈕、接(jie)觸器、熱繼電(dian)(dian)器以及保險絲(si)的好(hao)壞,從而(er)判定故障(zhang)的所在。通(tong)(tong)電(dian)(dian)試驗,聽(ting)其聲、測(ce)參數、判定故障(zhang),最后進行(xing)維修。如在電(dian)(dian)動(dong)機缺(que)相(xiang)(xiang)時,若測(ce)量三(san)相(xiang)(xiang)電(dian)(dian)壓值無法著判別時,就應該聽(ting)其聲,單獨測(ce)每(mei)相(xiang)(xiang)對地電(dian)(dian)壓,方(fang)可(ke)判定哪一相(xiang)(xiang)缺(que)損。
5.先清(qing)潔(jie)后維修(xiu),對污(wu)染較(jiao)重(zhong)的電氣設(she)備,先對其(qi)按鈕(niu)、接線點、接觸點進行清(qing)潔(jie),檢查外部控制鍵是否失靈(ling)。許多故障都是由臟污(wu)及(ji)導電塵塊引起的,一經清(qing)潔(jie)故障往(wang)往(wang)會(hui)排除(chu)。
6.先電(dian)源(yuan)后設(she)備(bei)電(dian)源(yuan)部分的故(gu)障率(lv)在整(zheng)個故(gu)障設(she)備(bei)中占的比例很高,所以先檢修電(dian)源(yuan)往往可(ke)以事半功倍(bei)。
7.先普遍后非(fei)凡(fan)(fan),因裝配配件質(zhi)量(liang)或其他設備(bei)故(gu)障(zhang)(zhang)(zhang)而引起(qi)的故(gu)障(zhang)(zhang)(zhang),一般占常見故(gu)障(zhang)(zhang)(zhang)的50左右(you)。電(dian)氣設備(bei)的非(fei)凡(fan)(fan)故(gu)障(zhang)(zhang)(zhang)多為軟(ruan)故(gu)障(zhang)(zhang)(zhang),要靠經(jing)驗和儀表(biao)來(lai)測(ce)量(liang)和維修(xiu)。
8.先(xian)(xian)外(wai)圍后內部(bu),先(xian)(xian)不要(yao)急于更換損壞的(de)電氣部(bu)件(jian),在確認(ren)外(wai)圍設(she)備電路正常時(shi),再考慮更換損壞的(de)電氣部(bu)件(jian)。
9.先直流(liu)后交流(liu),檢(jian)修時(shi),必須先檢(jian)查(cha)直流(liu)回(hui)路(lu)靜態工作點,再(zai)交流(liu)回(hui)路(lu)動態工作點。
10.先故(gu)障(zhang)后調試(shi),對于(yu)調試(shi)和故(gu)障(zhang)并存的電(dian)氣設備,應先排除故(gu)障(zhang),再進(jin)行調試(shi),調試(shi)必(bi)須在(zai)電(dian)氣線路速的前提下進(jin)行。
檢查方法和操作實踐
1.直觀(guan)法直觀(guan)法是根據電器故障(zhang)的(de)外(wai)部表現,通過看、聞、聽等(deng)手段,檢(jian)查、判(pan)定故障(zhang)的(de)方法。
(1)檢(jian)查(cha)步(bu)(bu)(bu)驟:調查(cha)情(qing)(qing)況(kuang):向操作(zuo)者(zhe)和故(gu)(gu)障(zhang)在場人(ren)員詢問情(qing)(qing)況(kuang),包括故(gu)(gu)障(zhang)外(wai)部(bu)表現(xian)、大(da)致部(bu)位(wei)、發生故(gu)(gu)障(zhang)時(shi)環境情(qing)(qing)況(kuang)。如有(you)(you)(you)(you)無(wu)(wu)異(yi)(yi)常(chang)(chang)氣(qi)體、明火、熱(re)源是(shi)否(fou)(fou)靠近電(dian)(dian)器、有(you)(you)(you)(you)無(wu)(wu)腐蝕性氣(qi)體侵入、有(you)(you)(you)(you)無(wu)(wu)漏水,是(shi)否(fou)(fou)有(you)(you)(you)(you)人(ren)修(xiu)理過,修(xiu)理的(de)內容等等。初(chu)步(bu)(bu)(bu)檢(jian)查(cha):根(gen)據調查(cha)的(de)情(qing)(qing)況(kuang),看有(you)(you)(you)(you)關(guan)電(dian)(dian)器外(wai)部(bu)有(you)(you)(you)(you)無(wu)(wu)損壞、連線有(you)(you)(you)(you)無(wu)(wu)斷路(lu)、松動,絕緣有(you)(you)(you)(you)無(wu)(wu)燒焦(jiao),螺旋熔(rong)(rong)斷器的(de)熔(rong)(rong)斷指(zhi)示器是(shi)否(fou)(fou)跳出,電(dian)(dian)器有(you)(you)(you)(you)無(wu)(wu)進水、油垢,開關(guan)位(wei)置是(shi)否(fou)(fou)正確等。試車(che):通過初(chu)步(bu)(bu)(bu)檢(jian)查(cha),確認有(you)(you)(you)(you)會使故(gu)(gu)障(zhang)進一(yi)步(bu)(bu)(bu)擴大(da)和造成人(ren)身、設備事(shi)故(gu)(gu)后,可進一(yi)步(bu)(bu)(bu)試車(che)檢(jian)查(cha),試車(che)中要注重有(you)(you)(you)(you)無(wu)(wu)嚴重跳火、異(yi)(yi)常(chang)(chang)氣(qi)味、異(yi)(yi)常(chang)(chang)聲(sheng)音等現(xian)象,一(yi)經發現(xian)應立(li)即停車(che),切斷電(dian)(dian)源。注重檢(jian)查(cha)電(dian)(dian)器的(de)溫升及電(dian)(dian)器的(de)動作(zuo)程(cheng)序是(shi)否(fou)(fou)符(fu)合電(dian)(dian)氣(qi)設備原理圖的(de)要求,從而發現(xian)故(gu)(gu)障(zhang)部(bu)位(wei)。
(2)檢(jian)查方法:觀察火(huo)(huo)(huo)花(hua):電(dian)(dian)器(qi)(qi)的(de)(de)觸(chu)(chu)(chu)點在閉合、分斷電(dian)(dian)路(lu)(lu)或導線(xian)(xian)線(xian)(xian)頭松(song)動(dong)(dong)(dong)(dong)(dong)時(shi)(shi)會產生火(huo)(huo)(huo)花(hua),因(yin)此可以(yi)根據(ju)火(huo)(huo)(huo)花(hua)的(de)(de)有(you)無(wu)、大(da)小(xiao)等現象來檢(jian)查電(dian)(dian)器(qi)(qi)故(gu)(gu)障(zhang)。例如,正(zheng)常(chang)(chang)(chang)緊固(gu)的(de)(de)導線(xian)(xian)與螺釘間(jian)發現有(you)火(huo)(huo)(huo)花(hua)時(shi)(shi),說明線(xian)(xian)頭松(song)動(dong)(dong)(dong)(dong)(dong)或接(jie)觸(chu)(chu)(chu)不良。電(dian)(dian)器(qi)(qi)的(de)(de)觸(chu)(chu)(chu)點在閉合、分斷電(dian)(dian)路(lu)(lu)時(shi)(shi)跳(tiao)火(huo)(huo)(huo)說明電(dian)(dian)路(lu)(lu)通(tong)(tong),不跳(tiao)火(huo)(huo)(huo)說明電(dian)(dian)路(lu)(lu)不通(tong)(tong)。控制電(dian)(dian)動(dong)(dong)(dong)(dong)(dong)機(ji)的(de)(de)接(jie)觸(chu)(chu)(chu)器(qi)(qi)主觸(chu)(chu)(chu)點兩相(xiang)有(you)火(huo)(huo)(huo)花(hua)、一相(xiang)無(wu)火(huo)(huo)(huo)花(hua)時(shi)(shi),表明無(wu)火(huo)(huo)(huo)花(hua)的(de)(de)一相(xiang)觸(chu)(chu)(chu)點接(jie)觸(chu)(chu)(chu)不良或這一相(xiang)電(dian)(dian)路(lu)(lu)斷路(lu)(lu);三相(xiang)中(zhong)兩相(xiang)的(de)(de)火(huo)(huo)(huo)花(hua)比(bi)(bi)(bi)正(zheng)常(chang)(chang)(chang)大(da),別(bie)一相(xiang)比(bi)(bi)(bi)正(zheng)常(chang)(chang)(chang)小(xiao),可初步判定為電(dian)(dian)動(dong)(dong)(dong)(dong)(dong)機(ji)相(xiang)間(jian)短路(lu)(lu)或接(jie)地;三相(xiang)火(huo)(huo)(huo)花(hua)都比(bi)(bi)(bi)正(zheng)常(chang)(chang)(chang)大(da),可能是(shi)電(dian)(dian)動(dong)(dong)(dong)(dong)(dong)機(ji)過(guo)載或機(ji)械部(bu)分卡住。在輔助電(dian)(dian)路(lu)(lu)中(zhong),接(jie)觸(chu)(chu)(chu)器(qi)(qi)線(xian)(xian)圈電(dian)(dian)路(lu)(lu)通(tong)(tong)電(dian)(dian)后,銜(xian)鐵(tie)不吸合,要分清是(shi)電(dian)(dian)路(lu)(lu)斷路(lu)(lu)還(huan)是(shi)接(jie)觸(chu)(chu)(chu)器(qi)(qi)機(ji)械部(bu)分卡住造成的(de)(de)。可按(an)一下啟動(dong)(dong)(dong)(dong)(dong)按(an)鈕,如按(an)鈕常(chang)(chang)(chang)開(kai)觸(chu)(chu)(chu)點閉合位置斷開(kai)時(shi)(shi)有(you)稍微的(de)(de)火(huo)(huo)(huo)花(hua),說明電(dian)(dian)路(lu)(lu)通(tong)(tong)路(lu)(lu),故(gu)(gu)障(zhang)在接(jie)觸(chu)(chu)(chu)器(qi)(qi)的(de)(de)機(ji)械部(bu)分;如觸(chu)(chu)(chu)點間(jian)無(wu)火(huo)(huo)(huo)花(hua),說明電(dian)(dian)路(lu)(lu)是(shi)斷路(lu)(lu)。動(dong)(dong)(dong)(dong)(dong)作(zuo)程序:電(dian)(dian)器(qi)(qi)的(de)(de)動(dong)(dong)(dong)(dong)(dong)作(zuo)程序應符合電(dian)(dian)氣說明書和(he)圖紙的(de)(de)要求。如某一電(dian)(dian)路(lu)(lu)上的(de)(de)電(dian)(dian)器(qi)(qi)動(dong)(dong)(dong)(dong)(dong)作(zuo)過(guo)早、過(guo)晚(wan)或不動(dong)(dong)(dong)(dong)(dong)作(zuo),說明該(gai)電(dian)(dian)路(lu)(lu)或電(dian)(dian)器(qi)(qi)有(you)故(gu)(gu)障(zhang)。另外,還(huan)可以(yi)根據(ju)電(dian)(dian)器(qi)(qi)發出的(de)(de)聲(sheng)音、溫度、壓(ya)力(li)、氣味等分析判定故(gu)(gu)障(zhang)。運用直觀法,不但可以(yi)確定簡單的(de)(de)故(gu)(gu)障(zhang),還(huan)可以(yi)把(ba)較(jiao)復(fu)雜的(de)(de)故(gu)(gu)障(zhang)縮小(xiao)到較(jiao)小(xiao)的(de)(de)范圍(wei)。
2.測(ce)(ce)(ce)(ce)量(liang)電(dian)壓法測(ce)(ce)(ce)(ce)量(liang)電(dian)壓法是根據(ju)電(dian)器的供電(dian)方式,測(ce)(ce)(ce)(ce)量(liang)各(ge)點的電(dian)壓值(zhi)與電(dian)流值(zhi)并(bing)與正常值(zhi)比較。具體可分為分階測(ce)(ce)(ce)(ce)量(liang)法、分段測(ce)(ce)(ce)(ce)量(liang)法和(he)點測(ce)(ce)(ce)(ce)法。
3.測電(dian)阻(zu)法(fa)(fa)可分為分階測量(liang)法(fa)(fa)和分段測量(liang)法(fa)(fa)。這兩種方(fang)法(fa)(fa)適(shi)用于(yu)開(kai)關、電(dian)器分布距離較大的電(dian)氣(qi)設備(bei)。
4.對比、置換(huan)元件、逐步(bu)開路(或(huo)接入(ru))法
(1)對比法(fa):把檢測數據與圖紙資料(liao)及平(ping)時(shi)記錄(lu)的(de)正(zheng)常(chang)參數相(xiang)比較來判(pan)定故障(zhang)(zhang)。對無(wu)資料(liao)又(you)無(wu)平(ping)時(shi)記錄(lu)的(de)電(dian)(dian)器(qi),可(ke)與同(tong)型號(hao)的(de)完好(hao)電(dian)(dian)器(qi)相(xiang)比較。電(dian)(dian)路中的(de)電(dian)(dian)器(qi)元(yuan)件(jian)屬于同(tong)樣控(kong)制(zhi)性質或(huo)多個元(yuan)件(jian)共(gong)同(tong)控(kong)制(zhi)同(tong)一(yi)設(she)備(bei)時(shi),可(ke)以利用其他(ta)相(xiang)似的(de)或(huo)同(tong)一(yi)電(dian)(dian)源的(de)元(yuan)件(jian)動(dong)作情況來判(pan)定故障(zhang)(zhang)。
(2)置轉換(huan)元(yuan)件(jian)(jian)(jian)法:某些電(dian)路的故障原因不易確定或檢查時(shi)間過長時(shi),但是為了保證電(dian)氣設備的利用率,可轉換(huan)同一相性能(neng)良好(hao)的元(yuan)器(qi)件(jian)(jian)(jian)實(shi)驗(yan),以證實(shi)故障是否(fou)由此(ci)電(dian)器(qi)引起(qi)。運用轉換(huan)元(yuan)件(jian)(jian)(jian)法檢查時(shi)應注重(zhong),當把原電(dian)器(qi)拆下后,要認真檢查是否(fou)已經損壞,只有肯定是由于(yu)該電(dian)器(qi)本身(shen)因素造成(cheng)損壞時(shi),才能(neng)換(huan)上新電(dian)器(qi),以免新換(huan)元(yuan)件(jian)(jian)(jian)再次損壞。
(3)逐步(bu)開(kai)(kai)(kai)路(lu)(lu)(lu)(lu)(或(huo)(huo)接(jie)入(ru))法(fa)(fa)(fa):多支路(lu)(lu)(lu)(lu)并聯(lian)且控制較(jiao)復雜的(de)(de)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)短(duan)(duan)路(lu)(lu)(lu)(lu)或(huo)(huo)接(jie)地(di)(di)時(shi),一(yi)(yi)般有明顯的(de)(de)外(wai)部(bu)(bu)表現(xian),如(ru)冒煙、有火花等。電(dian)(dian)(dian)(dian)動機(ji)內部(bu)(bu)或(huo)(huo)帶(dai)有護罩的(de)(de)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)短(duan)(duan)路(lu)(lu)(lu)(lu)、接(jie)地(di)(di)時(shi),除熔(rong)斷器(qi)熔(rong)斷外(wai),不(bu)易發現(xian)其(qi)他外(wai)部(bu)(bu)現(xian)象。這(zhe)(zhe)種情況可采用逐步(bu)開(kai)(kai)(kai)路(lu)(lu)(lu)(lu)(或(huo)(huo)接(jie)入(ru))法(fa)(fa)(fa)檢查。逐步(bu)開(kai)(kai)(kai)路(lu)(lu)(lu)(lu)法(fa)(fa)(fa):碰到難(nan)以檢查的(de)(de)短(duan)(duan)路(lu)(lu)(lu)(lu)或(huo)(huo)接(jie)地(di)(di)故障(zhang),可重(zhong)新更換(huan)熔(rong)體(ti),把(ba)多支路(lu)(lu)(lu)(lu)交(jiao)聯(lian)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu),一(yi)(yi)路(lu)(lu)(lu)(lu)一(yi)(yi)路(lu)(lu)(lu)(lu)逐步(bu)或(huo)(huo)重(zhong)點(dian)地(di)(di)從電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)中斷開(kai)(kai)(kai),然(ran)后通電(dian)(dian)(dian)(dian)試(shi)驗(yan),若熔(rong)斷器(qi)一(yi)(yi)再(zai)熔(rong)斷,故障(zhang)就(jiu)(jiu)在剛剛斷開(kai)(kai)(kai)的(de)(de)這(zhe)(zhe)條(tiao)(tiao)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)上(shang)。然(ran)后再(zai)將這(zhe)(zhe)條(tiao)(tiao)支路(lu)(lu)(lu)(lu)分成幾段,逐段地(di)(di)接(jie)入(ru)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)。當(dang)接(jie)入(ru)某段電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)時(shi)熔(rong)斷器(qi)又熔(rong)斷,故障(zhang)就(jiu)(jiu)在這(zhe)(zhe)段電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)及某電(dian)(dian)(dian)(dian)器(qi)元件上(shang)。這(zhe)(zhe)種方法(fa)(fa)(fa)簡(jian)單,但輕易把(ba)損壞不(bu)嚴重(zhong)的(de)(de)電(dian)(dian)(dian)(dian)器(qi)元件徹底燒毀。逐步(bu)接(jie)入(ru)法(fa)(fa)(fa):電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)出現(xian)短(duan)(duan)路(lu)(lu)(lu)(lu)或(huo)(huo)接(jie)地(di)(di)故障(zhang)時(shi),換(huan)上(shang)新熔(rong)斷器(qi)逐步(bu)或(huo)(huo)重(zhong)點(dian)地(di)(di)將各支路(lu)(lu)(lu)(lu)一(yi)(yi)條(tiao)(tiao)一(yi)(yi)條(tiao)(tiao)的(de)(de)接(jie)入(ru)電(dian)(dian)(dian)(dian)源,重(zhong)新試(shi)驗(yan)。當(dang)接(jie)到某段時(shi)熔(rong)斷器(qi)又熔(rong)斷,故障(zhang)就(jiu)(jiu)在剛剛接(jie)入(ru)的(de)(de)這(zhe)(zhe)條(tiao)(tiao)電(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)及其(qi)所(suo)包含的(de)(de)電(dian)(dian)(dian)(dian)器(qi)元件上(shang)。
5.強迫閉合法在排隊電器故(gu)障時,經過直(zhi)觀檢查后沒(mei)有找到故(gu)障點而手下也沒(mei)有適當(dang)的儀(yi)表(biao)進行測量,可用一絕緣棒(bang)將有關(guan)繼電器、接觸器、電磁鐵等用外力強行按下,使(shi)其常(chang)開觸點閉合,然(ran)后觀察電器部分或機械部分出(chu)現(xian)的各種現(xian)象,如電動(dong)機從(cong)不轉到轉動(dong),設備(bei)相應的部分從(cong)不動(dong)到正(zheng)常(chang)運行等。
6.短(duan)(duan)(duan)(duan)接(jie)(jie)(jie)(jie)法(fa)設備(bei)電(dian)(dian)路(lu)或電(dian)(dian)器(qi)的(de)故(gu)障(zhang)大致歸納(na)為短(duan)(duan)(duan)(duan)路(lu)、過載、斷路(lu)、接(jie)(jie)(jie)(jie)地、接(jie)(jie)(jie)(jie)線(xian)錯誤、電(dian)(dian)器(qi)的(de)電(dian)(dian)磁(ci)及機(ji)械(xie)部分故(gu)障(zhang)等六類(lei)。諸類(lei)故(gu)障(zhang)中出現較多的(de)為斷路(lu)故(gu)障(zhang)。它包括(kuo)導(dao)線(xian)斷路(lu)、虛(xu)連、松動、觸(chu)點接(jie)(jie)(jie)(jie)觸(chu)不良、虛(xu)焊(han)、假焊(han)、熔(rong)斷器(qi)熔(rong)斷等。對(dui)這類(lei)故(gu)障(zhang)除用(yong)電(dian)(dian)阻(zu)法(fa)、電(dian)(dian)壓法(fa)檢(jian)查(cha)外,還有一(yi)種(zhong)更為簡單(dan)可靠的(de)方法(fa),就(jiu)是(shi)(shi)短(duan)(duan)(duan)(duan)接(jie)(jie)(jie)(jie)法(fa)。方法(fa)是(shi)(shi)用(yong)一(yi)根良好絕緣的(de)導(dao)線(xian),將所懷疑(yi)的(de)斷路(lu)部位(wei)短(duan)(duan)(duan)(duan)路(lu)接(jie)(jie)(jie)(jie)起來,如(ru)短(duan)(duan)(duan)(duan)接(jie)(jie)(jie)(jie)到某處(chu),電(dian)(dian)路(lu)工(gong)作(zuo)恢復正(zheng)常,說(shuo)明(ming)該處(chu)斷路(lu)。具體(ti)操作(zuo)可分為局部短(duan)(duan)(duan)(duan)接(jie)(jie)(jie)(jie)法(fa)和(he)長短(duan)(duan)(duan)(duan)接(jie)(jie)(jie)(jie)法(fa)。以上幾種(zhong)檢(jian)查(cha)方法(fa),要活學活用(yong),遵守(shou)安全操作(zuo)規章(zhang)。對(dui)于連續燒壞的(de)元器(qi)件應(ying)查(cha)明(ming)原因后再進行更換;電(dian)(dian)壓測量(liang)時應(ying)考慮到導(dao)線(xian)的(de)壓降;不違反(fan)設備(bei)電(dian)(dian)器(qi)控(kong)制的(de)原則,試(shi)車時手(shou)不得離(li)開電(dian)(dian)源開關,并且保險應(ying)使用(yong)等量(liang)或略小于額定(ding)電(dian)(dian)流;,注重測量(liang)儀器(qi)的(de)擋位(wei)的(de)選擇。