短路测试

betway必威平台开展了300短circui CMP产品t tests in accordance with the IEC 61914 standard ‘cable cleats for electrical installations’. These tests include various peak faults, cable cleat spacing intervals, and cable formations to conclusively prove the cable cleats’ ability to withstand and resist a range of electromechanical forces according to IEC 61914. CMP Products has the technical resources, capabilities and capacity to engage with its clients and deliver bespoke solutions to suit new or unusual situations. The company is able to conduct physical short circuit tests on any of its cable cleats for project specific applications including: specific cable size / type, fault current, cable cleat, and fixing centre / spacing interval configurations.

根据IEC 61914测试对机电力的抵抗力

使用制造商或负责任供应商的峰值短路电流（IP）和初始窄尺寸的Symetical短路电流（i“k）如下进行短路测试。在该范围内有许多有线夹板，其中一个或多个类是必威东盟体育平台betway东盟体育
定义（请参阅IEC 61914 - 第5.1条）。此测试是在每个类中最临界大小执行的。

该测试在环境温度下进行，被认为是永久应用的定义温度，使用具有绞合铜导体的未armoured单芯600V / 1,000V电缆。使用所选择的电缆和电缆夹板组装试验台，是被测设备，使用完全记录的设备和电缆。必威东盟体育平台betway东盟体育然后在声明的短路电平的声明布置上进行测试。

Typical layout for testing for the resistance to electromechanical forces during short circuit:

出于测试的目的，电缆的布置可以如图1，图2或制造商或负责任供应商声明的任何其他配置所示。

One end of the test set-up is connected to a three phase supply and the other end to a short circuiting busbar, with all three phases connected. The cable is restrained at a minimum of 5 positions along the length of the cable run. Where intermediate restraints are used, at least 4
betway东盟体育必威东盟体育平台应使用电缆夹板和至少3个中间约束。betway东盟体育必威东盟体育平台电缆夹板和中间限制在使用的情况下，应同等间隔。电缆夹板betway东盟体育必威东盟体育平台固定至其将被适当地选择要考虑到所述机电力可能在测试过程中发生由生产商（例如，电缆梯）中所定义的安装表面。

Care is taken to ensure that the cross-sectional area of the cable is adequate for the magnitude and duration of the test current.

The manufacturer’s or responsible vendor’s catalogue references of the cable cleats and intermediate restraint (where used), the assembly details showing the spacing intervals and the external cable diameter used in the test shall be recorded.

测试设置经受三相短路的持续时间不小于0.1秒。测试的持续时间与任何其他相关数据一起记录。

IEC 61914 CLAUSE 9.5.2 FOR CABLE CLEATS AND INTERMEDIATE RESTRAINTS CLASSIFIED IN IEC 61914:2009 CLAUSE 6.4.3 / IEC 61914:2015 CLAUSE 6.4.4

(IEC 61914:2009 Clause 6.4.3 / IEC 61914:2015 Clause 6.4.4 Resistant to electromechanical forces, withstanding one short circuit)

betway东盟体育必威东盟体育平台在上述条款下分类的电缆夹板和中间限制应符合以下要求：

• there shall be no failure that will affect the intended function of holding the cables in place;
• the cable cleats and the intermediate restraints, if used, shall be intact with no missing parts (minor deformation is acceptable):
• 应当没有削减或损坏可见正常or corrected vision to the outer sheath of the cable caused by the cable cleats or by the intermediate restraints, if used.

IEC 61914 CLAUSE 9.5.3 FOR CABLE CLEATS AND INTERMEDIATE RESTRAINTS CLASSIFIED IN IN IEC 61914:2009 CLAUSE 6.4.4 / IEC 61914:2015 CLAUSE 6.4.5

(IEC 61914:2009 Clause 6.4.4 / IEC 61914:2015 Clause 6.4.5 Resistant to electromechanical forces, withstanding more than one short circuit)

Cable cleats and intermediate restraints classified under the aforementioned clauses shall comply with Clause 9.5.2. After a second short circuit application, a voltage withstand test is performed by applying a minimum test voltage of 2.8 kV d.c. for a period of (60+5 –0) seconds according to the provisions of IEC 60060-1:1989, ‘High-voltage test techniques – Part 1: General definitions and test requirements’, Clause 13.1, ‘Requirements for the test voltage’, and Clause 14.1, ‘Withstand voltage tests’. The voltage withstand test shall be administered between the cable cores and the mounting frame. The mounting frame shall be bonded to the earthing system. Where the cables incorporate screening or shielding, the screens and shields shall be bonded together and also bonded to the mounting frame. Where the cables do not incorporate screening or shielding, the cable jackets or sheaths and mounting frames shall be pre-wetted with sufficient water to facilitate a current leakage path along the outer jackets or sheaths. The cable jackets or sheaths and mounting frames shall be pre-wetted for (2+1–0) minutes before the test begins using water with a resistivity of (100+15–15 )?.m, which shall be measured immediately before starting the test.

The cables shall meet the requirements of the voltage withstand test without failure of the insulation.

短路电流引起的力量（IEC 61914）

短路期间电流的特性取决于许多因素，包括与发电机的电分离。下图示出了远从发电机短路的典型的电流与时间特性。A.c.在这种情况下的组件具有恒定的幅度（I“k = IK）并且叠加在衰减的D.C组件上，I D.C.这从初始值，a，零落下。

SPECIFICATION OF THE TEST CURRENT

A complete specification of short circuit currents should give the currents as a function of time at the short circuit location from the initiation of the short circuit up to its end. In most practical cases, this is not necessary. It is usually sufficient to know the peak current, ip, and the values of the initial r.m.s symmetrical, I”k, and steady state, Ik, currents.

In order to specify the current used in a short circuit test the following are quoted:

• the peak current, ip;
• 初始窄下的短路电流，i“k;
• the short circuit duration, t.

CALCULATION OF THE MECHANICAL FORCES BETWEEN CONDUCTORS

作用在导体上的电磁力由导体中的电流和来自相邻导体的磁场决定。在电缆装置中，导体之间的距离通常很小，因此力可能是相当大的。在两个平行导体的情况下，导体上的电磁力可以从等式B1导出：

f（t）= b（t）·i（t）·l

• l是长度;
• f（t）是导体上的瞬时电磁力;
• B（t）是来自相邻导体的瞬时磁场;
• i(t) is the momentary current in the neighbouring conductor.

如果是D.C.忽略短路电流的组分，瞬时力具有正弦变化，其频率是电流频率的频率（等式B.1）。D.C.组件给出了一个衰变的力组件，其频率与系统频率相同。

For the two parallel conductors in figure above, the magnetic field from current i1, at the location of the other conductor is:

B =？0·H =？0·I1 / 2·？·S.（b.2）

在哪里？o = 4·？·10-7（h / m）
and the mechanical force is:

F = i2 × B = i2 ·?0 · i1 / 2·? · S（b.3）

his equation is usually written as:

Fs = 0.2 · i1 · i2 / S (B.4)

In this equation, the force is given in N/m, i in kA and S in metres. The evaluation of Equation B.4 requires S >> d but gives an acceptable accuracy when the current distribution is uniform (or symmetrical) within the conductors.

向量方程B.3确认如果两个电流具有180°的相位角差，并且力被引导朝向具有相同相角的电流的电流，则拒绝两个平行导体。

In a three phase system, the magnetic field in Equation B.2 is the resulting momentary vector value from the other two phases.

对于具有平坦配置的导体的三相短路，两个外导体上的力总是从中央导体引导。中央导体上的力是振荡的。扁平地层中外导体上的最大力可以通过以下计算：

Fƒo = 0.16 ip2 / S（B.5）

The maximum force on the middle conductor in flat formation can be calculated by:

Fƒm = 0.17 ip2 / S（B.6）

For a three phase short circuit with the cables in a trefoil configuration the maximum force on the conductor is:

ft = 0.17 IP2 / s（B.7）

在哪里:

Fsis the maximum force on the cable conductor in flat formation for a single phase short circuit [N/m];

Fƒo是三相短路的扁平地层外部电缆导体上的最大力[n / m];

Fƒm是三相短路扁平地层中的中心电缆导体上的最大力[n / m];

Ft是三相短路[n / m]的三相电路配置中的电缆导体上的最大力;

IP.峰值短路电流[ka];

dis the external diameter of the conductor [m];

S是两个相邻导体之间的中心距离的中心[m]。