How can I verify the Itrms value in the SCR datasheet? Is there a way to measure it? Or perhaps derive it using other measured parameters? Can anyone please teach me how I can display it in the curve tracer? Thanks in advance.
Itrms is a power rating parameter and can't be easily verified. It's calculated by the manufacturer based on long term reliability requirements.
You can at best determine the Vt versus It characteristic and the on-state power dissipation for a particular load case. If you know the thermal resistances, you can estimate the junction temperature in this operation mode and check, if it's safe according to the specifcation.