Formulas for Short-Circuit Current and Voltage at Fault Point (Constant & Variable Currents)

Give me the formulas for the short-circuit current and the voltage at the short-circuit point for the currents:
-constant
-changeable

There are no general formulas for short circuit current or short circuit voltage. Alternatively, you can talk about the short-circuit current and voltage in the transformer, or calculate them based on a given diagram, ....
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With these short-circuit currents it basically comes down to knowing the resistance of the circuit in which the short-circuit occurred (direct current) or the impedance (alternating current), both values are in ohms.

The current that flows comes down to the law of the Ohm whatever you look at
I = U / R. If you measure the voltage that prevails on the piece of circuit you are interested in and you know its resistance, but the impedance is the current you already have.

For direct current everything is nice and beautiful, but for alternating current one must take into account that usually the circuits are not purely resistive and there is a phase shift between the current and voltage. There is a way, too, complex numbers have been used for it. You can then calculate the maximum value of the current and the phase shift. You can also calculate it traditionally, but whoever knows complex numbers will never do it normally again

Short-circuit current - single-phase short-circuit in TN network:

I = (c * root (3) * Un) / (z1 + z2 + z0) where
c - coefficient which is: 0.8 for the selection of security
1.1 to check the strength of the cable
Un - rated voltage of the network,
z1 - short-circuit impedance (as a complex number) - positive sequence,
z2 - as above - negative sequence,
z0 - as above - zero sequence