[ghouse]

As the new conductors will have lower impedance, some breakers may need to be replaced to interrupt higher fault current. Otherwise, it's likely the only substation equipment needing to upgrade would be series compensation stations which may have lower normal and emergency ratings than the upgraded conductors.

More likely is that lower impedance on the reconductored circuit will cause increased flows on other, non-upgraded circuits, either requiring those to be reconductored, or installing phase-shifting tranformers or reactors to limit current.

[pdx_flyer]

Good points.

Have you seen a lot of phase-shifting transformers in the U.S.? In my experience they've mostly been in Europe with a few specialized applications in the States.

I would think a utility would want to reconductor the other circuits otherwise they're leaving benefits on the table right?

[ghouse]

I only know the western US. And my experience is consistant with your own -- specialized applications.

They would love to reconductor the other circuits. In the US, the utilities make a guaranteed rate of return on investments in the transmission system. So, anything they regulators will let them do, they'll do -- not necessarily because it has technical benefits, but because it has economic benefits.

This is one reason why reconductoring isn't that popular with utilities -- it allows the utility to get more capacity with less spend, so less profit.

[pdx_flyer]

Fair enough. I had a conversation with one utility that was fine with transformers popping (even if preventable) because a popped transformer becomes a capitalizable expense.

[sitkack]

If substations are being upgraded, they should also be installing batteries and inverters at the substations at the same time.

[infecto]

This sounds like moving the goal and a much more difficult problem than just upgrading the substation.