Hi,
a brief explanation about signal voltages:
In a OPAMP circuit (in regulation = non saturated):
* the IN+ voltage determines the IN- voltage. --> The OPAMP regulates the output in a way that IN- becomes the same as IN+
Now in your case
* IN+ = GND = 0V, thus IN- also becomes 0V, too.
* since you have the two diodes in series, the limiter becomes active when the voltage across the diodes (V_Out - V_IN-) is V_fwd + V_rev of the diodes = 0.6V + V_Zener.
* and this in both directions.
(in real world neither 0.6V nor V_Zener will be precise. Both depend on production, current and temperature)
**
If you use such a diode limiter across the feedback with a non inverting OPAMP circuit .. then the voltage at IN+ is not constant, it is the input voltage.
So it limits at (V_IN+) +/- (V_fwd + V_rev).
***
If I wanted the limiter to be non inverting, I´d use two inverting circuits in series.
But often "inverted signals" are no problem at all. In detail it depends on your application´s requirements.
***
It is for dc applications only.
What do you mean?
Klaus