OSM-EE 18/5（EN 62368-1）測(cè)量接觸電流時(shí)的地線通斷狀態(tài)

Standard: EN 62368-1:2014

Subject: Touch current measurement

Confirmed by TC108 at Busan, Korea, Oct 2018

Question:

Standard EN 62368-1 in clause 5.7.4 requires that at least one earthed accessible part shall be subjected to touch current measurement and refers to IEC/EN 60990:1999 for conditions of measurements.

a) Is it required to open switch e while conducting relevant faults 6.2.2.2 to 6.2.2.8 (parallel operation of switch e open with other switches)?

b) if a) is yes, doesn’t this means double fault (fault in earthing and in addition fault in network)?

Decision:

a) YES

b) NO, OSM is of the opinion that opening switch "e" is a loss of a safeguard. For measurements on class I equipment switch "e" must be open together with any combination of the other switches in the figure one at the time. Except for the line conductor switch "I" which simulates a line/neutral fault in the installation. If however the equipment contains a single pole mains switch,it shall additionally be tested with the mains switch in the equipment open and closed

問(wèn)題：

EN 62368-1第5.7.4條款要求至少對(duì)一個(gè)接地的可觸及導(dǎo)電零部件在電源連接故障后測(cè)量接觸電流，測(cè)量方案參考IEC/EN 60990

a）測(cè)量IEC/EN 60990第6.2.2.2至6.2.2.8條款時(shí)，是否需要打開(kāi)開(kāi)關(guān)e？

b）假如a成立，是否形同雙重故障（接地故障和斷網(wǎng)故障）

決定：

a）是。要打開(kāi)開(kāi)關(guān)e

b）不。OSM認(rèn)為打開(kāi)開(kāi)關(guān)e是一種無(wú)保護(hù)行為。對(duì)于Ⅰ類設(shè)備的測(cè)量，開(kāi)關(guān)e必須打開(kāi)后，再與其他開(kāi)關(guān)進(jìn)行任意組合，但用于模擬三相設(shè)備火零線故障的開(kāi)關(guān)I除外。如果設(shè)備有單極電源開(kāi)關(guān)，則要在設(shè)備啟動(dòng)和關(guān)閉狀態(tài)分別進(jìn)行測(cè)量

大俠提示：

以上是星形TN或TT系統(tǒng)設(shè)備接觸電流測(cè)量網(wǎng)絡(luò)原理圖（本篇不談及三相設(shè)備，但原理相同，朋友們自行翻閱IEC 60990即可）

開(kāi)關(guān)e模擬不可靠接地設(shè)備保護(hù)接地導(dǎo)體斷開(kāi)故障

開(kāi)關(guān)n模擬設(shè)備中性線導(dǎo)體斷開(kāi)故障

開(kāi)關(guān)p模擬設(shè)備火零線極性反轉(zhuǎn)

由于IEC/EN 60990第6.2.2.2至6.2.2.8條款要求每次只施加一個(gè)故障，所以凡是某個(gè)測(cè)量部位與地有電氣連接，不論接地是否可靠（保護(hù)接地或功能接地），測(cè)量該部位的接觸電流時(shí)開(kāi)關(guān)e一律要打開(kāi)（斷開(kāi)接地）再配合n/p開(kāi)關(guān)（設(shè)備有單極開(kāi)關(guān)則再加入啟動(dòng)和關(guān)閉狀態(tài)）做任意組合測(cè)量。即使這時(shí)候是斷開(kāi)接地也斷開(kāi)零線的狀態(tài)，不認(rèn)為是雙重故障。因?yàn)槿绻粩嚅_(kāi)接地，測(cè)量接觸電流值會(huì)遠(yuǎn)遠(yuǎn)小于真實(shí)值（漏電流從接地那兒溜走了）

掃描二維碼，添加關(guān)注“朱大俠的質(zhì)檢江湖”微信公眾號(hào)，更多有趣安規(guī)小知識(shí)等著您哦~