Hello!
All 3 technologies are the same, but their cost is different. Perhaps something overlaps somewhere, and you get 3 identical technologies instead of one, or maybe they should be different.
Default mod settings.

they are different ;-)

Excellent!
Then maybe I should correct the description and add a little more understanding of what technology is related to what?
Right now they are all the same.

[technology-name]
expand-sector-tech-a=Expand Sector
expand-sector-tech-b=Expand Sector
expand-sector-tech-c=Expand Sector

[technology-description]
expand-sector-tech-a=Expand Sector Increases the size of a sector in which Smart Linked Chests can share their content.
expand-sector-tech-b=Expand Sector Increases the size of a sector in which Smart Linked Chests can share their content.
expand-sector-tech-c=Expand Sector Increases the size of a sector in which Smart Linked Chests can share their content.

[technology-effect-description]
expand-sector=Expand the sector size of the logistic network by 0.5 chunk in each direction.

there has to be a bit of a surprise ;-)
it was copy paste ;-) and the very first description in the early days

I think it expands with 1, 5 or 10 tiles or so, definitely progressive. maybe subject to change, but so far no one has complained

to be exact
chest_sectorSize * 32 + ((tech_level_a-1) * 4 + (tech_level_b-1) * 8 + (tech_level_c-1) * 12)

Um... why 3 modifiers? I don’t quite understand, but I’ll be glad to understand, so to speak, to learn from experience :)

because low-level science should expand less than high-level science,
i can only increase the cost per technology and not add new science packs at higher levels.
i could hide the previous technology if a new one is available, so that only one is visible
or I can hide then the previous technology if the old ony has a maximum
but at the moment all 3 are infinite researches
and there was no reason to change that

Maybe then make the option that you suggested, at the early stage of the game 1 technology is available, not expensive, for example up to level 10, then at the level of the middle game 2 technology is available, but already more expensive (but the bonuses from it also enter into the equation when you start to study it), also available up to level 10, well and already at the middle-late level of the game 3 technology is available (after fully studying the first and second), which is a little expensive, but it is infinite, and when you start to study it, the bonuses from it (like the 3 modifier in the equation) are already quite decent, thereby giving a significant increase (but not cheating, well, there must be at least some difficulty for the game :)))))

It's just confusing at the moment.
I don't know why no one asked about this aspect before...
- either no one wanted to bother, these 3 technologies give something, well, let them give,
- or it's disabled in the settings,
- or it was just not clear to me, and I decided to find out :)

OK, but where is the reason to change the whole thing? What really bothers you?

Oh, sure, I'm not insisting, I'm just sharing my thoughts and experience of using this mod. There's no point in changing anything, except the appearance and a bit of an unclear technology (well, it's clearer now, after the explanation). It's not that I don't care, I just wanted, how can I put it more correctly - "to help improve the user experience" :)