How to add "Diac" in OrCAD?
I asked my question and let me answer mine. Yes, there is no part like Diac in OrCAD. Maybe they didn't need this but I needed, so, I made an great working :)

The zeners voltage are about your choice to edit diac's VBO voltage. Diac's have got breakover voltage to work. I used thyristors and zeners to build up my diac. Now my VBO=28Volt approx. That's it :)