If you just wanted to make a 3cp version of turbine, this map works, but some of the changes you've made indicates to me you want to improve the layout of turbine. If I'm wrong, well then you can disregard this feedback. But there are some things that turbine does poorly I feel you could change.

(Ignore the garbage quality, I'm on a dogwater computer currently.)
It might be hard to tell from the image, but you can snipe out of spawn. If you rotate the spawn door 90 degrees like on Gullywash/Sunshine, it should solve the problem.

You can see into the spawnroom, which is problematic because if you are capping last, you can see which way the enemies choose to leav spawn and more effectively spawncamp them.

Widening the vents is a good change, but they still are very chokey. You could open them up and turn them into a lobby area. You have a good deal of space to work with, so you can really reinvigorate this area.
MId is pretty good, but one of the biggest problems with the middle is the sniper sightlines.

All of the sniper sightlines are straight lines between the choke points. There is no real nuance in your positioning like on other maps, and no risk to sniping.

This area near the forward spawn isn't really an interesting area, although it is a much more useful route since the enemy spawn isn't right next to it when you are using it. It could use some more health so attackers could use it more reliably
I'm gonna list off some other stuff that don't really need an image along side it.
- I really like how you widened batts on mid, the highground there is less awkward and is actually pertinent to the mid fight.
- Sentry guns on top of the crates are still very powerful, maybe you could make mid bigger so you can spam them more effectively from the entrances.
- Mid needs a little more positioning I feel. Right now players only fight over the crates and the turbines. Add some more height advantages and the like for teams to fight over. A good example of this is most competitive 5cp maps. Process and Granary have pretty similar Mids to this, although I'd be taking more inspiration from Process since Granary's Mid isn't very good.
- The Vents could use a more consistent way to get into them from last. It would make pushing out of last a lot less annoying.
- You can't tell what team's side you are on based on the walls, change the dev textures on the walls or floors based on what side you are on.
- Right now the (from the perspective of spawn) right connector from Last to Mid is the only real effective route into last. Maybe make other entrances more useful to attackers.
Turbine has loads of potential as a map, and I feel this map could be a good way of unlocking it.