与前一个的进化。设置
因此，该策略基于逐步增加当前阈值
当我们接近
电源。与当前的歧视情况一样，该研究基于
比较保护装置的时间-电流跳闸曲线。
这种协调：
•易于学习和实施；
•相对便宜；
•能够实现甚至更高的歧视水平，这取决于I
的cw
上游装置；
•允许保护功能冗余，并可发送有效信息
到控制系统，
但有以下缺点：
•保护装置（尤其是
靠近放射源的）泄漏率高，即使在未受辐射影响的区域，也存在明显的安全和组件损坏问题
故障；
ABB |保护和控制装置117
3保护协调
3.1保护协调
E4S4000
T7H1600 E3N2500
U Ur=15000 V
Ik=60kA
Sr=2500 kVA
Ur2=400 V
英国%=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
时间-电流曲线
•它只允许在链的较低层次使用限流断路器；其他断路器必须能够
承受与通道相关的热应力和电动应力
故意延时的故障电流。选择性断路器，
通常为空气式，必须用于各种级别，以确保足够的
高短时耐受电流；
•短路电流引起的干扰持续时间
未受故障影响的区域内的电源电压可能会导致电子和机电设备出现问题（电压低于
电磁释放值）；
•歧视级别的数量受到
网络可以稳定运行。
以下示例显示了获得的时间判别的典型应用
通过不同设置不同保护装置的跳闸时间。

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.