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日常生(sheng)活(huo)中，我們(men)時刻都需要跟電打(da)交道，那么用電安全(quan)問題就擺(bai)在了(le)首(shou)位，為了(le)提高(gao)用電安全(quan)性，多級(ji)漏(lou)電保(bao)護系統就起(qi)到了(le)很關鍵的作用。但多級(ji)漏(lou)電保(bao)護并不(bu)是簡單的疊加使用漏(lou)電保(bao)護開(kai)關，在選(xuan)(xuan)型(xing)方面是很有講究(jiu)的，如果不(bu)注(zhu)意漏(lou)電保(bao)護開(kai)關的選(xuan)(xuan)型(xing)，施工過程中會出現(xian)下(xia)級(ji)保(bao)護跳閘(zha)，上級(ji)保(bao)護跳閘(zha)，或者上下(xia)級(ji)同時跳閘(zha)的現(xian)象。如何避免多級(ji)漏(lou)電保(bao)護由于選(xuan)(xuan)型(xing)不(bu)當造成越(yue)級(ji)跳閘(zha)，一起(qi)來看(kan)一下(xia)：

此處以典(dian)型的三級漏電保護(hu)進行闡述(shu)

一級保護設置在電源總開關(guan)處(chu)，主(zhu)要功(gong)能是當主(zhu)干線發(fa)生(sheng)接地故障時進(jin)行保護；

二級保(bao)護(hu)設置在(zai)分(fen)支(zhi)線路上，主(zhu)要(yao)功(gong)能是提(ti)供人(ren)體間(jian)接接觸電擊保(bao)護(hu)或(huo)因漏電而(er)發生(sheng)的電氣火災保(bao)護(hu)；

三級保護(hu)設置在(zai)電(dian)(dian)網末端(duan)，主要功能是提供人體直接(jie)接(jie)觸(chu)電(dian)(dian)擊(ji)保護(hu)。

一、總保護的選擇

總保護的目(mu)的是防止干線(xian)斷線(xian)接(jie)(jie)地、金屬(shu)性接(jie)(jie)地等(deng)故(gu)障(zhang)引發的電(dian)氣火災、跨步電(dian)壓觸(chu)電(dian)及間接(jie)(jie)接(jie)(jie)觸(chu)觸(chu)電(dian)事故(gu)。

用于總線(xian)路(lu)保(bao)護的剩余(yu)電(dian)流保(bao)護器(qi)，為(wei)防止越級跳閘或頻(pin)繁(fan)動(dong)(dong)作(zuo)，影響供(gong)電(dian)的可(ke)靠性，動(dong)(dong)作(zuo)電(dian)流值除(chu)按上述兩條件選(xuan)(xuan)擇外，還應考(kao)慮(lv)選(xuan)(xuan)擇具有(you)延時動(dong)(dong)作(zuo)特性的延時型剩余(yu)電(dian)流保(bao)護器(qi)。為(wei)了更好地與下(xia)一(yi)級保(bao)護配合，延時動(dong)(dong)作(zuo)時間(jian)的選(xuan)(xuan)擇應大于0.4S以上的優選(xuan)(xuan)延時動(dong)(dong)作(zuo)時間(jian)值，也可(ke)選(xuan)(xuan)用鑒相鑒幅剩余(yu)電(dian)流保(bao)護器(qi)。

二、分支保護的選擇

分(fen)支(zhi)保(bao)護(hu)的(de)(de)(de)(de)目的(de)(de)(de)(de)是防止(zhi)分(fen)支(zhi)線(xian)路包括進戶線(xian)發生接地漏(lou)電(dian)(dian)(dian)(dian)故障或用電(dian)(dian)(dian)(dian)設備外殼漏(lou)電(dian)(dian)(dian)(dian)等，引起的(de)(de)(de)(de)間接接觸(chu)觸(chu)電(dian)(dian)(dian)(dian)及(ji)電(dian)(dian)(dian)(dian)氣火災。但分(fen)支(zhi)保(bao)護(hu)范圍(wei)比末端保(bao)護(hu)大(da)(da)得多，分(fen)支(zhi)網絡的(de)(de)(de)(de)泄露電(dian)(dian)(dian)(dian)流相應(ying)增大(da)(da)。選擇(ze)剩余電(dian)(dian)(dian)(dian)流保(bao)護(hu)器時，其額定(ding)動作電(dian)(dian)(dian)(dian)流應(ying)大(da)(da)于電(dian)(dian)(dian)(dian)網正常漏(lou)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流的(de)(de)(de)(de)2倍(bei)以上(shang)，漏(lou)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流應(ying)是在(zai)惡劣的(de)(de)(de)(de)氣候條件下測出的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)網漏(lou)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)流max值。

剩(sheng)余(yu)電流(liu)保護器的動作電流(liu)應滿足以(yi)下條件

I△n >= 2I0 I△n >= 3I△n1

I△n—剩余電(dian)流(liu)保護(hu)器額定動(dong)作(zuo)電(dian)流(liu)；

I0—電(dian)網漏電(dian)電(dian)流；

I△n1—下一(yi)級保護(hu)的剩(sheng)余電(dian)流保護(hu)器的額定動作電(dian)流。

選擇(ze)同(tong)時滿足以上條件的額定(ding)(ding)動作電流max值(zhi)，作為分支保護的額定(ding)(ding)動作電流值(zhi)。

用(yong)于分支保(bao)護(hu)(hu)的(de)剩余(yu)電流保(bao)護(hu)(hu)器(qi)，宜選(xuan)用(yong)具有0.2～0.4S延時動作時間的(de)延時型剩余(yu)電流保(bao)護(hu)(hu)器(qi)，也可選(xuan)用(yong)反時限動作特(te)性(xing)的(de)剩余(yu)電流保(bao)護(hu)(hu)器(qi)。

三、末級保護的選擇

末(mo)級保(bao)護(hu)主要(yao)(yao)以(yi)防止人(ren)身直(zhi)接接觸(chu)觸(chu)電(dian)(dian)(dian)為(wei)主要(yao)(yao)目的(de)，安裝在家庭(ting)用電(dian)(dian)(dian)器(qi)(qi)(qi)設(she)(she)備(bei)、移動式電(dian)(dian)(dian)力設(she)(she)備(bei)、手持式電(dian)(dian)(dian)動電(dian)(dian)(dian)熱工具及臨時(shi)用電(dian)(dian)(dian)設(she)(she)備(bei)上，這就(jiu)要(yao)(yao)求選擇高靈敏度快(kuai)速動作(zuo)型的(de)剩余(yu)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)保(bao)護(hu)器(qi)(qi)(qi)。按(an)規定(ding)，剩余(yu)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)保(bao)護(hu)器(qi)(qi)(qi)額(e)定(ding)動作(zuo)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)小于(yu)(yu)或等于(yu)(yu)30mA、額(e)定(ding)分斷時(shi)間小于(yu)(yu)0.1S。當漏電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)達(da)到(dao)250mA或超(chao)過額(e)定(ding)動作(zuo)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)的(de)5倍時(shi)，分斷時(shi)間應小于(yu)(yu)0.04S。因此應用于(yu)(yu)末(mo)端作(zuo)直(zhi)接接觸(chu)觸(chu)電(dian)(dian)(dian)保(bao)護(hu)的(de)剩余(yu)電(dian)(dian)(dian)流(liu)(liu)(liu)(liu)保(bao)護(hu)器(qi)(qi)(qi)，應進行(xing)嚴(yan)格的(de)選擇。

當多個(ge)漏電(dian)(dian)保護裝置(zhi)串(chuan)聯使(shi)用時，上下級(ji)漏電(dian)(dian)保護裝置(zhi)之間實現選(xuan)擇(ze)性(xing)動(dong)作(zuo)，可(ke)減少停(ting)電(dian)(dian)范圍。實現上下級(ji)選(xuan)擇(ze)性(xing)動(dong)作(zuo)的(de)方式有：

①上級漏電保護(hu)裝(zhuang)置的額定(ding)剩(sheng)余動作電流至少為下級漏電保護(hu)裝(zhuang)置的額定(ding)剩(sheng)余動作電流的3倍。

②不論接地故障電(dian)流(liu)為多(duo)少，上級漏電(dian)保(bao)護裝置的(de)不動(dong)作時間應大于下級漏電(dian)保(bao)護裝置的(de)動(dong)作時間。