Fault surge

Switching surges due to simultaneous CB closing on a three-phase line. 

A circuit for a fault surge analysis, (a) Original circuit, (b) An equivalent circuit, (c) An L equivalent of (b). 

For example, neglecting the source inductance and the surge impedance [Zq] at the right of node P with the source voltage E =Ecos Qt), the following phase b (sound phase) voltage is derived  

Considering (cOq/cOi) is far smaller than 1 and p=2k/3, the following approximate solutions of the sound phases b and c voltages are obtained  

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The steady state power generation characteristics of the plant are derived and analyzed. Understanding the transient behavior of SOFC is important for control of stationary utility generators during power system faults, surges and switchings. 

As explained in Section 2.2.2.1.1, a transformer is represented by its leakage inductance for most switching surge analyses. When dealing with a fault surge, especially in a low voltage... 

It is a common practice to classify the fault-clearing surge not as a closing surge but as a fault surge since it occurs as a consequence of a fault. 

Figure 2.28 compares the effect of a fault surge on untransposed and transposed doublecircuit lines. The fault is initiated at the re-ceiving end of one circuit as illustrated in the figure. The circuit configuration is equivalent to the model circuit illustrated in Figure 2.26 in which the fault occurs at the middle of the line. 

Calculated results of fault surge on a 1100-kV circuit, (a) A 1100-kV model circuit, (b) Faulty circuit, (c) Sound circuit. 

Figure 2.31 shows an example of a fault-clearing surge. The maximum overvoltage is observed to be 1.5 pu, which is greater than that of the 1.32 pu fault surge in Figure 2.26. The overvoltage increases to about 1.6 pu in the two phase-to-ground fault cases and to about 2.0 pu in the three phase-to-ground fault cases.

Fault surge Some kHz/0.1-20 ms Line-to-ground fault Fault clearing... 

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