低(Di)压(Ya)配(Pei)电(Dian)系(Xi)统(Tong)施(Shi)工(Gong)规(Gui)范(Fan)

根(Gen)据(Ju)现(Xian)行(Xing)的(De)标(Biao)准(Zhun)《(?)低(Di)压(Ya)配(Pei)电(Dian)设(She)计(Ji)规(Gui)范(Fan)》(?)(GB50054)的(De)定(Ding)义(Yi)，(?)将(Jiang)低(Di)压(Ya)配(Pei)电(Dian)系(Xi)统(Tong)分(Fen)为(Wei)三(San)种(Zhong)，(?)即(Ji)TN、(?)TT、(?)IT三(San)种(Zhong)形(Xing)式(Shi)。(?)其(Qi)中(Zhong)，(?)一(Yi)个(Ge)大(Da)写(Xie)字(Zi)母(Mu)T表(Biao)示(Shi)电(Dian)源(Yuan)变(Bian)压(Ya)器(Qi)中(Zhong)性(Xing)点(Dian)直(Zhi)接(Jie)接(Jie)地(Di);I则(Ze)表(Biao)示(Shi)电(Dian)源(Yuan)变(Bian)压(Ya)器(Qi)中(Zhong)性(Xing)点(Dian)不(Bu)接(Jie)地(Di)(或(Huo)通(Tong)过(Guo)高(Gao)阻(Zu)抗(Kang)接(Jie)地(Di))。(?)第(Di)二(?)个(Ge)大(Da)写(Xie)字(Zi)母(Mu)T表(Biao)示(Shi)电(Dian)气(Qi)设(She)备(Bei)的(De)外(Wai)壳(Ke)直(Zhi)接(Jie)接(Jie)地(Di)，(?)但(Dan)和(He)电(Dian)网(Wang)的(De)接(Jie)地(Di)系(Xi)统(Tong)没(Mei)有(You)联(Lian)系(Xi);N表(Biao)示(Shi)电(Dian)气(Qi)设(She)备(Bei)的(De)外(Wai)壳(Ke)与(Yu)系(Xi)统(Tong)的(De)接(Jie)地(Di)中(Zhong)性(Xing)线(Xian)相(Xiang)连(Lian)。(?)

TN系(Xi)统(Tong)：(?)电(Dian)源(Yuan)变(Bian)压(Ya)器(Qi)中(Zhong)性(Xing)点(Dian)接(Jie)地(Di)，(?)设(She)备(Bei)外(Wai)露(Lu)部(Bu)分(Fen)与(Yu)中(Zhong)性(Xing)线(Xian)相(Xiang)连(Lian)。(?)

TT系(Xi)统(Tong)：(?)电(Dian)源(Yuan)变(Bian)压(Ya)器(Qi)中(Zhong)性(Xing)点(Dian)接(Jie)地(Di)，(?)电(Dian)气(Qi)设(She)备(Bei)外(Wai)壳(Ke)采(Cai)用(Yong)保(Bao)护(Hu)接(Jie)地(Di)。(?)

IT系(Xi)统(Tong)：(?)电(Dian)源(Yuan)变(Bian)压(Ya)器(Qi)中(Zhong)性(Xing)点(Dian)不(Bu)接(Jie)地(Di)(或(Huo)通(Tong)过(Guo)高(Gao)阻(Zu)抗(Kang)接(Jie)地(Di))，(?)而(?)电(Dian)气(Qi)设(She)备(Bei)外(Wai)壳(Ke)电(Dian)气(Qi)设(She)备(Bei)外(Wai)壳(Ke)采(Cai)用(Yong)保(Bao)护(Hu)接(Jie)地(Di)。(?)

一(Yi)、(?) TN系(Xi)统(Tong)

电(Dian)力(Li)系(Xi)统(Tong)的(De)电(Dian)源(Yuan)变(Bian)压(Ya)器(Qi)的(De)中(Zhong)性(Xing)点(Dian)接(Jie)地(Di)，(?)根(Gen)据(Ju)电(Dian)气(Qi)设(She)备(Bei)外(Wai)露(Lu)导(Dao)电(Dian)部(Bu)分(Fen)与(Yu)系(Xi)统(Tong)连(Lian)接(Jie)的(De)不(Bu)同(Tong)方(Fang)式(Shi)又(You)可(Ke)分(Fen)三(San)类(Lei)：(?)即(Ji)TN—(?)C系(Xi)统(Tong)、(?)TN—(?)S系(Xi)统(Tong)、(?)TN—(?)C—(?)S系(Xi)统(Tong)。(?)下(Xia)面(Mian)分(Fen)别(Bie)进(Jin)行(Xing)介(Jie)绍(Shao)。(?)

1、(?)TN—(?)C系(Xi)统(Tong)

其(Qi)特(Te)点(Dian)是(Shi)：(?)电(Dian)源(Yuan)变(Bian)压(Ya)器(Qi)中(Zhong)性(Xing)点(Dian)接(Jie)地(Di)，(?)保(Bao)护(Hu)零(Ling)线(Xian)(PE)与(Yu)工(Gong)作(Zuo)零(Ling)线(Xian)(N)共(Gong)用(Yong)。(?)

(1)它(Ta)是(Shi)利(Li)用(Yong)中(Zhong)性(Xing)点(Dian)接(Jie)地(Di)系(Xi)统(Tong)的(De)中(Zhong)性(Xing)线(Xian)(零(Ling)线(Xian))作(Zuo)为(Wei)故(Gu)障(Zhang)电(Dian)流(Liu)的(De)回(Hui)流(Liu)导(Dao)线(Xian)，(?)当(Dang)电(Dian)气(Qi)设(She)备(Bei)相(Xiang)线(Xian)碰(Peng)壳(Ke)，(?)故(Gu)障(Zhang)电(Dian)流(Liu)经(Jing)零(Ling)线(Xian)回(Hui)到(Dao)中(Zhong)点(Dian)，(?)由(You)于(Yu)短(Duan)路(Lu)电(Dian)流(Liu)大(Da)，(?)因(Yin)此(Ci)可(Ke)采(Cai)用(Yong)过(Guo)电(Dian)流(Liu)保(Bao)护(Hu)器(Qi)切(Qie)断(Duan)电(Dian)源(Yuan)。(?)TN—(?)C系(Xi)统(Tong)一(Yi)般(Ban)采(Cai)用(Yong)零(Ling)序(Xu)电(Dian)流(Liu)保(Bao)护(Hu);

(2)TN—(?)C系(Xi)统(Tong)适(Shi)用(Yong)于(Yu)三(San)相(Xiang)负(Fu)荷(He)基(Ji)本(Ben)平(Ping)衡(Heng)场(Chang)合(He)，(?)如(Ru)果(Guo)三(San)相(Xiang)负(Fu)荷(He)不(Bu)平(Ping)衡(Heng)，(?)则(Ze)PEN线(Xian)中(Zhong)有(You)不(Bu)平(Ping)衡(Heng)电(Dian)流(Liu)，(?)再(Zai)加(Jia)一(Yi)些(Xie)负(Fu)荷(He)设(She)备(Bei)引(Yin)起(Qi)的(De)谐(Xie)波(Bo)电(Dian)流(Liu)也(Ye)会(Hui)注(Zhu)入(Ru)PEN，(?)从(Cong)而(?)中(Zhong)性(Xing)线(Xian)N带(Dai)电(Dian)，(?)且(Qie)极(Ji)有(You)可(Ke)能(Neng)高(Gao)于(Yu)50V，(?)它(Ta)不(Bu)但(Dan)使(Shi)设(She)备(Bei)机(Ji)壳(Ke)带(Dai)电(Dian)，(?)而(?)且(Qie)还(Huan)无(Wu)法(Fa)取(Qu)得(De)稳(Wen)定(Ding)的(De)基(Ji)准(Zhun)电(Dian)位(Wei);

(3)TN—(?)C系(Xi)统(Tong)应(Ying)将(Jiang)PEN线(Xian)重(Zhong)复(Fu)接(Jie)地(Di)，(?)其(Qi)作(Zuo)用(Yong)是(Shi)当(Dang)接(Jie)零(Ling)的(De)设(She)备(Bei)发(Fa)生(Sheng)相(Xiang)与(Yu)外(Wai)壳(Ke)接(Jie)触(Chu)时(Shi)，(?)可(Ke)以(Yi)有(You)效(Xiao)地(Di)减(Jian)少(Shao)零(Ling)线(Xian)对(Dui)地(Di)电(Dian)压(Ya)。(?)

由(You)上(Shang)可(Ke)知(Zhi)，(?)TN-C系(Xi)统(Tong)存(Cun)在(Zai)以(Yi)下(Xia)缺(Que)陷(Xian)：(?)

A、(?)当(Dang)三(San)相(Xiang)负(Fu)载(Zai)不(Bu)平(Ping)衡(Heng)时(Shi)，(?)在(Zai)零(Ling)线(Xian)上(Shang)出(Chu)现(Xian)不(Bu)平(Ping)衡(Heng)电(Dian)流(Liu)，(?)零(Ling)线(Xian)对(Dui)地(Di)呈(Cheng)现(Xian)电(Dian)压(Ya)。(?)当(Dang)三(San)相(Xiang)负(Fu)载(Zai)严(Yan)重(Zhong)不(Bu)平(Ping)衡(Heng)时(Shi)，(?)触(Chu)及(Ji)零(Ling)线(Xian)可(Ke)能(Neng)导(Dao)致(Zhi)触(Chu)电(Dian)事(Shi)故(Gu)。(?)

B、(?)通(Tong)过(Guo)漏(Lou)电(Dian)保(Bao)护(Hu)开(Kai)关(Guan)的(De)零(Ling)线(Xian)，(?)只(Zhi)能(Neng)作(Zuo)为(Wei)工(Gong)作(Zuo)零(Ling)线(Xian)，(?)不(Bu)能(Neng)作(Zuo)为(Wei)电(Dian)气(Qi)设(She)备(Bei)的(De)保(Bao)护(Hu)零(Ling)线(Xian)，(?)这(Zhe)是(Shi)由(You)于(Yu)漏(Lou)电(Dian)开(Kai)关(Guan)的(De)工(Gong)作(Zuo)原(Yuan)理(Li)所(Suo)决(Jue)定(Ding)的(De)。(?)

C、(?)对(Dui)接(Jie)有(You)二(?)极(Ji)漏(Lou)电(Dian)保(Bao)护(Hu)开(Kai)关(Guan)的(De)单(Dan)相(Xiang)用(Yong)电(Dian)设(She)备(Bei)，(?)如(Ru)用(Yong)于(Yu)TN-C系(Xi)统(Tong)中(Zhong)其(Qi)金(Jin)属(Shu)外(Wai)壳(Ke)的(De)保(Bao)护(Hu)零(Ling)线(Xian)，(?)严(Yan)禁(Jin)与(Yu)该(Gai)电(Dian)路(Lu)的(De)工(Gong)作(Zuo)零(Ling)线(Xian)相(Xiang)连(Lian)接(Jie)，(?)也(Ye)不(Bu)允(Yun)许(Xu)接(Jie)在(Zai)漏(Lou)电(Dian)保(Bao)护(Hu)开(Kai)关(Guan)前(Qian)面(Mian)的(De)PEN线(Xian)上(Shang)，(?)但(Dan)在(Zai)使(Shi)用(Yong)中(Zhong)极(Ji)易(Yi)发(Fa)生(Sheng)误(Wu)接(Jie)。(?)