# Correction Factors¶

## Voltage Corection Factor c¶

The voltage correction factors $$c_{min}$$ for minimum and $$c_{max}$$ for maximum short-circuit currents are applied in calculating short-circuit impedances for some elements (transformer, ext_grid) as well as for the equivalent voltage source for the calculation of the initials short-circuit current $$I''_k$$.

It is defined for each bus depending on the voltage level. In the low voltage level, there is an additional distinction between networks with a tolerance of 6% vs. a tolerance of 10% for $$c_{max}$$:

Voltage Level $$c_{min}$$ $$c_{max}$$
< 1 kV Tolerance 6% 0.95 1.05
Tolerance 10% 1.10
> 1 kV 1.00

## Peak Factor $$\kappa$$¶

The factor $$\kappa$$ is used for calculation of the peak short-circuit current $$i_p$$, thermal equivalent short-circuit current $$I_{th}$$ and unsymmetrical short-circuit currents.

In radial networks, $$\kappa$$ is given as:

$\kappa = 1.02 + 0.98 e^{-\frac{3}{R/X}}$

where $$R/X$$ is the R/X ratio of the equivalent short-circuit impedance $$Z_k$$ at the fault location.

In meshed networks, the standard defines three possibilities for the definition of $$\kappa$$:

a ) Uniform Ratio R/X b ) Ratio R/X at short-circuit location c ) Equivalent frequency

pandapower implements version b), in which the factor $$\kappa$$ is given as:

$\kappa = [1.02 + 0.98 e^{-\frac{3}{R/X}}] \cdot 1.15$

while being limited with $$\kappa_{min} < \kappa < \kappa_{max}$$ depending on the voltage level:

Voltage Level $$\kappa_{min}$$ $$\kappa_{max}$$
< 1 kV 1.0 1.8
> 1 kV 2.0

## Thermal Factors m and n¶

The factors m and n are necessary for the calculation of the thermal equivalent short-circuit current $$I_{th}$$.

pandapower currently only implements short-circuit currents far from synchronous generators, where:

$n = 1$

and m is given as:

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

where $$\kappa$$ is defined as above and $$T_k$$ is the duration of the short-circuit current that can be defined as a parameter when running the short-circuit calculation.