对于标准IEC 61439-1详述的情况，断路器允许
避免对配电盘进行短路耐受验证。条款
8.2.3.1标准“豁免
短路耐受强度的验证”表明：
“试验中不需要验证短路耐受强度
以下情况…
对于受具有截止电流的限流装置保护的组件
大允许预期短路电流不超过17 kA
在组件进线电路的端子处……”
上一页中的示例包含在
标准：如果断路器用作配电盘中的主断路器
安装在预期短路电流
为90 kA时，无需进行短路验证
承受
2.3极限曲线
ABB |保护和控制装置93
2一般特征
1SDC08013F0001
我
2t[106 A2s]
100
10
1
0.10
0.01
1 10 100 1000
x Irms[kA]
0.218毫安时
90 kA
2.4特定通过能量曲线
在短路的情况下，受故障影响的设备部件会受到
与故障电流平方成正比的热应力
以及保护装置断开电流所需的时间。这个
跳闸期间保护装置释放的能量称为“特定能量”
让能量通过”（I2
t） ，在A2中测量
s、 了解
在各种故障条件下，特定的通过能量对于
装置各部分的尺寸标注和保护。
限制的效果和减少的行程时间会影响
特定通过能量。对于跳闸的电流值
断路器由脱扣器的定时、断路器的
通过将有效故障电流的平方乘以保护装置跳闸所需的时间来获得特定的通过能量；在其他
在这种情况下，可以从以下公式中获得特定通过能量的值：
下图。
以下是从400 V电压下XT2L 160/20型断路器的特定通电能量曲线图中读取的示例。
x轴显示对称的预期短路电流，而
y轴显示特定的通过能量值，以MA2表示
s
对应于等于90 kA的短路电流，断路器允许
通过I2值
t等于0.218Ma2
s

circuit-breakers allows, for the cases detailed by Standard IEC 61439-1, the avoidance of short-circuit withstand verifications for switchboards. Clause 8.2.3.1 of the Standard “Circuits of ASSEMBLIES which are exempted from the verification of the short-circuit withstand strength” states that: “A verification of the short-circuit withstand strength is not required in the following cases… For ASSEMBLIES protected by current-limiting devices having a cut-off current not exceeding 17 kA at the maximum allowable prospective short-circuit current at the terminals of the incoming circuit of the ASSEMBLY...” The example in the previous page included among those considered by the Standard: if the circuit-breaker was used as a main breaker in a switchboard to be installed in a point of the plant where the prospective short-circuit current is 90 kA, it would not be necessary to carry out the verification of short-circuit withstand. 2.3 Limitation curves ABB | Protection and control devices 93 2 General characteristics 1SDC008013F0001 I 2t [106 A2s] 100.00 10.00 1.00 0.10 0.01 1 10 100 1000 x Irms [kA] 0.218 MA2s 90 kA 2.4 Specific let-through energy curves In case of short-circuit, the parts of a plant affected by a fault are subjected to thermal stresses which are proportional both to the square of the fault current as well as to the time required by the protection device to break the current. The energy let through by the protection device during the trip is termed “specific let-through energy” (I2 t), measured in A2 s. The knowledge of the value of the specific let-through energy in various fault conditions is fundamental for the dimensioning and the protection of the various parts of the installation. The effect of limitation and the reduced trip times influence the value of the specific let-through energy. For those current values for which the tripping of the circuit-breaker is regulated by the timing of the release, the value of the specific let-through energy is obtained by multiplying the square of the effective fault current by the time required for the protection device to trip; in other cases the value of the specific let-through energy may be obtained from the following diagrams. The following is an example of the reading from a diagram of the specific letthrough energy curve for a circuit-breaker type XT2L 160 In 20 at 400 V. The x-axis shows the symmetrical prospective short-circuit current, while the y-axis shows the specific let-through energy values, expressed in MA2 s. Corresponding to a short-circuit current equal to 90 kA, the circuit-breaker lets through a value of I2 t equal to 0.218 MA2 s.