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對于標準IEC 61439-1詳述的情況，斷路器允許
避免對配電盤進行短路耐受驗證。條款
8.2.3.1標準“豁免
短路耐受強度的驗證”表明：
“試驗中不需要驗證短路耐受強度
以下情況…
對于受具有截止電流的限流裝置保護的組件
大允許預期短路電流不超過17 kA
在組件進線電路的端子處……”
上一頁中的示例包含在
標準：如果斷路器用作配電盤中的主斷路器
安裝在預期短路電流
為90 kA時，無需進行短路驗證
承受
2.3極限曲線
ABB |保護和控制裝置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毫安時
90 kA
2.4特定通過能量曲線
在短路的情況下，受故障影響的設備部件會受到
與故障電流平方成正比的熱應力
以及保護裝置斷開電流所需的時間。這個
跳閘期間保護裝置釋放的能量稱為“特定能量”
讓能量通過”（I2
t） ，在A2中測量
s、 了解
在各種故障條件下，特定的通過能量對于
裝置各部分的尺寸標注和保護。
限制的效果和減少的行程時間會影響
特定通過能量。對于跳閘的電流值
斷路器由脫扣器的定時、斷路器的
通過將有效故障電流的平方乘以保護裝置跳閘所需的時間來獲得特定的通過能量；在其他
在這種情況下，可以從以下公式中獲得特定通過能量的值：
下圖。
以下是從400 V電壓下XT2L 160/20型斷路器的特定通電能量曲線圖中讀取的示例。
x軸顯示對稱的預期短路電流，而
y軸顯示特定的通過能量值，以MA2表示
s
對應于等于90 kA的短路電流，斷路器允許
通過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.
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