ith.rst

Thermal Short-Circuit Current

Current Calculation

The equivalent thermal current is calculated as:

\begin{bmatrix}
\underline{I}_{th, 1} \\
\vdots  \\
\underline{I}_{th, n} \\
\end{bmatrix} =
\begin{bmatrix}
\sqrt{m_1 + n_1} \\
\vdots  \\
\sqrt{m_n + n_n} \\
\end{bmatrix}
\begin{bmatrix}
\underline{I}''_{k, 1} \\
\vdots  \\
\underline{I}''_{k, n} \\
\end{bmatrix}

where m and n represent the dc and ac part of the thermal load.

Correction Factors m and n

For short-circuit currents far from synchronous generators, the factors are given as:

n = 1
m = \frac{1}{2 \cdot f \cdot T_k \cdot ln(\kappa - 1)} [e^{4 \cdot f \cdot T_k \cdot ln(\kappa - 1)} - 1]

where \kappa is the peak factor defined :ref:`here <kappa>` and T_k is the duration of the short-circuit current that can be defined as a parameter when running the short-circuit calculation.