Thank you c_mitra, gumattos and KlausST for your responses. They were very helpful.
I understand that the chart shown in the picture attached can be used to determine the initial CTR for a design with the optocoupler
from ambient temperature.
View attachment 135161
But, how is the ambient temperature determined? Why I am asking this question is that a system is normally cased and the temperature
inside the case while the system is running is likely to be higher than that outside.
It may seem a very basic question but please bear with me. Thanks.
---Akanimo