断开时间足够短，以防止短路电流达到其本来可以达到的峰值”（IEC 60947-2，定义2.3）。
实际上，ABB SACE塑壳断路器SACE Tmax XT和Tmax T
在短路条件下，串联极为迅速（跳闸时间为
大约几毫秒），因此不可能使用时间电流
协调研究曲线。
这些现象主要是动态的（因此与平方成正比）
，并且可以使用特定的
让我们通过能量曲线。
通常，有必要验证断路器下游的通电能量是否低于完成断路器连接所需的能量值
打开上游断路器。
这种歧视肯定比以前更难考虑
因为它在很大程度上取决于两个设备之间的交互
按系列放置，要求访问数据，但终往往无法访问
使用者制造商提供表格、规则和计算程序，其中
给出了不同组合之间的小鉴别极限
断路器。
优势：
•快速断开，跳闸时间随着短路电流而减少
增加；
•减少故障造成的损坏（热应力和动态应力），
对供电系统的干扰，成本。。。；
•歧视水平不再受短期价值的限制
耐受电流I
装置能够承受的cw；
•大量歧视级别；
•协调不同限流装置（保险丝、断路器等）的可能性即使它们位于沿
链条

break time short enough to prevent the short-circuit current reaching its otherwise attainable peak value” (IEC 60947-2, def. 2.3). In practice, ABB SACE moulded-case circuit-breakers SACE Tmax XT and Tmax T series, under short-circuit conditions, are extremely rapid (tripping times of about some milliseconds) and therefore it is impossible to use the time-current curves for the coordination studies. The phenomena are mainly dynamic (and therefore proportional to the square of the instantaneous current value) and can be described by using the specific let-through energy curves. In general, it is necessary to verify that the let-through energy of the circuitbreaker downstream is lower than the energy value needed to complete the opening of the circuit-breaker upstream. This type of discrimination is certainly more difficult to consider than the previous ones because it depends largely on the interaction between the two devices placed in series and demands access to data often unavailable to the end user. Manufacturers provide tables, rules and calculation programs in which the minimum discrimination limits are given between different combinations of circuit- breakers. Advantages: • fast breaking, with tripping times which reduce as the short-circuit current increases; • reduction of the damages caused by the fault (thermal and dynamic stresses), of the disturbances to the power supply system, of the costs...; • the discrimination level is no longer limited by the value of the short-time withstand current I cw which the devices can withstand; • large number of discrimination levels; • possibility of coordination of different current-limiting devices (fuses, circuitbreakers,..) even if they are positioned in intermediate positions along the chain