Can Board B1 Be Used for Requirement R1 Without Modifications?

[PhysicsTest]

TL;DR Summary

Want to understand the operating voltage and the nominal voltage

I have this doubt suppose a i have a board (B1) which operates in the range from 36V - 90V and the nominal operating range is 72V. I have another requirement (R1) with operating range 36V - 56V and with nominal operating range of 48V but functionally same as B1. So, can i use the board B1 for R1 requirement without any modifications? What is the significance of the nominal operating range in this case 72V and 48V? I am struggling to understand.

 

[Baluncore]

The range of B1 is from 36 V to 90 V, with a normal operating point (not range) of 72 V.
The range of R1 is from 36 V to 56 V, with a normal operating point (not range) of 48 V.
You should be able to run them both from 48 V.
But examine the specs of B1 to find out if it must be derated when run on the lower voltage.

 

[PhysicsTest]

When you have to operate an electronics circuit board over larger voltage range, will the size of the components inside the board changes. How the design basically looks like, first they will consider the operating point, design the complete circuit then see if that component works for the entire range of operation? or it is only the input section components will change like regulator etc, to accommodate the operating range and the components inside the board will not change?

 

[Baluncore]

Anything is possible. You should not have to change components.
You cannot expect more than a general answer so long as B1 and R1 are unidentified.

 

[berkeman]

When you have to operate an electronics circuit board over larger voltage range, will the size of the components inside the board changes. How the design basically looks like, first they will consider the operating point, design the complete circuit then see if that component works for the entire range of operation? or it is only the input section components will change like regulator etc, to accommodate the operating range and the components inside the board will not change?

Have you studied switching power supply design yet? That is the main consideration in your question, I think (but I'm not sure, since the question is defined in kind of a strange way).

The main consideration in the power supply design to accommodate the input voltage range is the duty cycle of the switching power supply. Depending on the topology of the switching power supply circuit, there are limitations on the variation of the duty cycle of the switching. The input-to-output voltage ratio of such circuits depends on the duty cycle of the switching action.