As per my understanding, you are trying to understand the characteristics of “Saturable transformer” block found in the library browser.
To address your queries, it's important to distinguish between two concepts: the "Hysteresis Loop" and the "Magnetizing Curve". Hysteresis loop accounts for the instantaneous magnetising flux in the core when current is taken through one complete sinusoidal cycle. The core is excited with the currents of different amplitudes and a hysteresis loop is drawn corresponding to each of them. The figure below illustrates examples of hysteresis loops generated when the core is subjected to sinusoidal currents with different peak amplitudes.
In order to do a simplified analysis, the tip of all the hysteresis loops are joined together to get a “B-H curve” as shown by “red-dotted” line in the above figure. (This is also called piecewise linear relationship between the flux and magnetization current)
Refer to the below given documentation for “saturable transformer” block:
Now, addressing your query “If I specify the initial flux, do I also need to adjust it in my saturation characteristic or can I leave the values there as they are?”
Refer to the below figure.
If you wish to specify a residual flux, denoted as "phi0," the second point of the saturation characteristic should correspond to a zero current, as illustrated in figure (b). This means that the initial flux point "phi0" must be positioned on the piecewise linear characteristics. For instance, if you want the initial flux in the transformer core to be "phi0" = 0.8 P.U., then the second point must necessarily be (0, phi2), where "phi2" is greater than or equal to 0.8. In summary, there is no need to entirely change the saturation characteristics, just change it near the origin, such that it also includes the point “(0, phi0)”
The saturation characteristic is entered as “(i, phi)” pair values in per units, starting with pair (0, 0).
I hope it helps !
