Transformer Impedance? 12

[Mbrooke]

How does changing a transformer's impedance during ordering change its construction? If impedance was not a concern (totally disregarded) during design and manufacturing, what would it typically come out to be?


40/50/60MVA units are what I have in mind but really this applies to any power transformer.

 

[crshears]

PRC wrote:

In combined cycle thermal power stations, normally there will be two GSUs one taking power from gas turbine generator and a smaller one from steam generator. To reduce footprint at yard, it is possible to combine these in to one with two primaries of different voltages and ratings with one secondary feeding power to grid.

Hmmm . . . technically very feasible, but advisable? In stations where the number of gas turbines is >1, it would be better IMHO to have separate main output transformers [MOTs] for each gas turbine and the steam turbine; that way in the event of the failure of a GTMOT the balance of the plant can still operate, and if the STMOT fails the balance of the plant can still be run in simple cycle if required [provided the necessary by-passing etc. is readily available]. I would think that reducing the yard footprint would have to of very high and overriding priority before such an approach would be warranted.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[davidbeach]

For a 1 + 1 combined cycle plant the shared GSU makes sense and is quite common. In a 6 + 1 plant I’m aware of pairs of CTs share GSUs and the ST has its own GSU.

 

[crshears]

6+1? Wow! Two GTs to 1 GSU makes sense in that configuration. I'm curious, though: does each GT still have its own HRSG?

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[davidbeach]

Yep, one HRSG per CT. My understanding is that when new it was the largest combined cycle plant in the world but it's difficult to check something like that.