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傾向于在這些限制范圍內(nèi)操作，而其他人不操作。”
（IEC 60947-1，定義2.5.23）；
可以區(qū)分：
•完全歧視，這意味著“過電流歧視
在兩個過流保護裝置串聯(lián)的情況下，保護裝置
在負載側(cè)提供保護，而不會使另一個保護裝置跳閘
裝置”（IEC 60947-2，定義2.17.2）；
•部分歧視，即“過電流歧視，導(dǎo)致
在兩個過流保護裝置串聯(lián)的情況下，保護裝置
在負載側(cè)提供高達給定過電流限制的保護，而無需
另一個跳閘”（IEC 60947-2，定義2.17.3）；該過電流閾值為
稱為“鑒別極限電流為
“（IEC 60947-2，定義2.17.4）。
當(dāng)前歧視
這種類型的判別是基于觀察到斷層越近
到達網(wǎng)絡(luò)饋線時，短路電流將越大。我們
因此，只需通過校準(zhǔn)即可定位故障發(fā)生的區(qū)域
裝置上游的瞬時保護達到極限值高于
導(dǎo)致下游裝置跳閘的故障電流。
我們通常只能在特定情況下實現(xiàn)完全歧視
故障電流不是很高（與設(shè)備的額定電流相當(dāng)）或
當(dāng)高阻抗部件位于兩個保護裝置之間時
（例如變壓器、很長或很小的電纜……）產(chǎn)生巨大差異
短路電流值之間。
因此，這種協(xié)調(diào)主要在終分配中是可行的
網(wǎng)絡(luò)（具有低額定電流和短路電流值以及高
連接電纜的阻抗）。
研究中通常使用裝置的時間-電流跳閘曲線。
該解決方案是：
•快速；
•易于實施；
•價格低廉。
另一方面：
•歧視限制通常較低；
•提高識別級別導(dǎo)致設(shè)備尺寸快速增長。
tended to operate within these limits does so, while the others do not operate”
(IEC 60947-1, def. 2.5.23);
It is possible to distinguish between:
• total discrimination, which means “over-current discrimination such that, in
the case of two over-current protective devices in series, the protective device
on the load side provides protection without tripping the other protective
device” (IEC 60947-2, def. 2.17.2);
• partial discrimination, which means “over-current discrimination such that, in
the case of two over-current protective devices in series, the protective device
on the load side provides protection up to a given over-current limit without
tripping the other” (IEC 60947-2, def. 2.17.3); this over-current threshold is
called “discrimination limit current Is
” (IEC 60947-2, def. 2.17.4).
Current discrimination
This type of discrimination is based on the observation that the closer the fault
comes to the network’s feeder, the greater the short-circuit current will be. We
can therefore pinpoint the zone where the fault has occurred simply by calibrating
the instantaneous protection of the device upstream to a limit value higher than
the fault current which causes the tripping of the device downstream.
We can normally achieve total discrimination only in specific cases where the
fault current is not very high (and comparable with the device’s rated current) or
where a component with high impedance is between the two protective devices
(e.g. a transformer, a very long or small cable...) giving rise to a large difference
between the short-circuit current values.
This type of coordination is consequently feasible mainly in final distribution
networks (with low rated current and short-circuit current values and a high
impedance of the connection cables).
The devices’ time-current tripping curves are generally used for the study.
This solution is:
• rapid;
• easy to implement;
• and inexpensive.
On the other hand:
• the discrimination limits are normally low;
• increasing the discrimination levels causes a rapid growing of the device sizes.
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