This example shows a purely electric circuit containing a VariableResistor component (R3).
The resistance of R3 is determined depending on time function of component Ramp.
It starts at a very small value (0.01 Ohm) and reaches 5 Ohm after 10 s.

Using this example, we would like to give an idea how one can decide if the system
is in a quasi-stationary mode or not.

The main (and only) time constant of the system reads `T = L*(R2+R3)/(R2*R3)`.
It is well-known for first-order components that, after a step-like change of an
input signal, the output signal reaches 95 % of �ts final value after a time period
of `3*T`.
This time period is called `decayTime`.
Checking the difference between `decayTime` and the time interval of the
simulation experiment yields the information if the system is in a quasi-stationary
mode.

Because of variable resistor R3, it is necessary to calculate `decayTime`
during the simulation experiment according to `decayTime = 3*L*(R2+R3)/(R2*R3)`.
The Boolean `quasiStationaryOk` tests if `decayTime` is smaller than
the simulation interval `tInterval` (which is necessary for quasi-stationary
mode).
Hence in the **first part** of the simulation (Time < 2.4 s), the system is
**not** in a **quasi-stationary** mode and the appropriate points in time of the
result curves represent only a series of steady states without any correlation with time.
In the **second part** of the simulation (Time > 2.4 s), the system **is
quasi-stationary** and the result curves reflect a correct relationship with time.

Simulate until 10 s.

Plot in seperate windows`V.v`,`R2.v`,`L.v`versus "Time"`L.vRe`and`L.vIm`versus "Time"`quasiStationaryOk`versus "Time"

Fraunhofer IIS/EAS, Dresden

email: olaf.enge@eas.iis.fraunhofer.de

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