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與前一個的進化。設(shè)置
因此，該策略基于逐步增加當(dāng)前閾值
當(dāng)我們接近
電源。與當(dāng)前的歧視情況一樣，該研究基于
比較保護裝置的時間-電流跳閘曲線。
這種協(xié)調(diào)：
•易于學(xué)習(xí)和實施；
•相對便宜；
•能夠?qū)崿F(xiàn)甚至更高的歧視水平，這取決于I
的cw
上游裝置；
•允許保護功能冗余，并可發(fā)送有效信息
到控制系統(tǒng)，
但有以下缺點：
•保護裝置（尤其是
靠近放射源的）泄漏率高，即使在未受輻射影響的區(qū)域，也存在明顯的安全和組件損壞問題
故障；
ABB |保護和控制裝置117
3保護協(xié)調(diào)
3.1保護協(xié)調(diào)
E4S4000
T7H1600 E3N2500
U Ur=15000 V
Ik=60kA
Sr=2500 kVA
Ur2=400 V
英國%=6%
E4S 4000 PR121-LSI In4000
E3N 2500 PR121-LSI In2500
T7H 1600 PR332-LI In1600
104
103
102
101
1.
10 -1
10 -2
I[kA]1 10 1
[s]
10 2 10 3
1SDC00015F0001
時間-電流曲線
•它只允許在鏈的較低層次使用限流斷路器；其他斷路器必須能夠
承受與通道相關(guān)的熱應(yīng)力和電動應(yīng)力
故意延時的故障電流。選擇性斷路器，
通常為空氣式，必須用于各種級別，以確保足夠的
高短時耐受電流；
•短路電流引起的干擾持續(xù)時間
未受故障影響的區(qū)域內(nèi)的電源電壓可能會導(dǎo)致電子和機電設(shè)備出現(xiàn)問題（電壓低于
電磁釋放值）；
•歧視級別的數(shù)量受到
網(wǎng)絡(luò)可以穩(wěn)定運行。
以下示例顯示了獲得的時間判別的典型應(yīng)用
通過不同設(shè)置不同保護裝置的跳閘時間。
evolution from the previous one. The setting strategy is therefore based on progressively increasing the current thresholds and the time delays for tripping the protective devices as we come closer to the power supply source. As in the case of current discrimination, the study is based on a comparison of the time-current tripping curves of the protective devices. This type of coordination: • is easy to study and implement; • is relatively inexpensive; • enables to achieve even high discrimination levels, depending on the I cw of the upstream device; • allows a redundancy of the protective functions and can send valid information to the control system, but has the following disadvantages: • the tripping times and the energy levels that the protective devices (especially those closer to the sources) let through are high, with obvious problems concerning safety and damage to the components even in zones unaffected by the fault; ABB | Protection and control devices 117 3 Protection coordination 3.1 Protection coordination E4S4000 T7H1600 E3N2500 U Ur = 15000 V Ik=60kA Sr = 2500 kVA Ur2 = 400 V uk% = 6% E4S 4000 PR121-LSI In4000 E3N 2500 PR121-LSI In2500 T7H 1600 PR332-LI In1600 104 103 102 101 1 10 -1 10 -2 I [kA] 1 10 1 [s] 10 2 10 3 1SDC008015F0001 Time-current curves • it enables the use of current-limiting circuit-breakers only at levels hierarchically lower down the chain; the other circuit-breakers have to be capable of withstanding the thermal and electro-dynamic stresses related to the passage of the fault current for the intentional time delay. Selective circuit-breakers, often air type, have to be used for the various levels to guarantee a sufficiently high short-time withstand current; • the duration of the disturbance induced by the short-circuit current on the power supply voltages in the zones unaffected by the fault can cause problems with electronic and electro-mechanical devices (voltage below the electromagnetic releasing value); • the number of discrimination levels is limited by the maximum time that the network can stand without loss of stability. The following example shows a typical application of time discrimination obtained by setting differently the tripping times of the different protection devices.
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