5MW XFR on 115KV

[Okpower]

Hi, All:

I am getting involved in a new project, for a Gas Processing Plant. The entire Plant needs 4,7 MW to operate, and according the visualization studies, this power will be supplied by two 115/13.8 KV transformers in redundant double bar (two 115 KV incoming lines).
My questions:
1.- Is it practical to feed the plant in 115 KV?
2.- Are there Electrical Factories that manufacture 115KV transformer with that capacity (5MW)??

Thanks in advance

 

[dpc]

1. Sure. There are no technical issues - only economic considerations.

2. Yes. It's on the small side for a 115 kV winding, but you should not have any problems finding a supplier.

 

[Zogzog]

That is a little small but you will find one. I have a 110kV/13.2kV 7.5MVA, so it os not that unusual.

 

[slavag]

Im with Dave (dpc), it's only economic issue.
According to some economic evaluation ( in our area, with our prices),decition between MV and HV is about 25-28MW.
Regards.
Slava

 

[ScottyUK]

4.7MW to operate and your source will be 5MVA... hope it has a good power factor! One decent sized drive starting might be enough to tip the whole lot over the edge.

Are you at the stage of load flow and motor starting studies or just conceptual stage? If the latter I would be estimating the transformers a little larger, just to account for the things you omitted to factor in: planning for 94% loading is unreasonable and will be a real headache later if you find you need a bit more capacity, especially with what is likely to be a pretty expensive transformer.



----------------------------------

If we learn from our mistakes I'm getting a great education!

 

[rcw retired EE]

I agree with Zog & Scotty - 5 MW is too small a transformer.

Feeding at 115kV is not a problem. Buy a transformer 10 MVA or larger. The cost difference between 7.5 & 10 MVA is probably smaller than expected at that voltage. At 10 MVA you are still within the ratings of typical 13.8 kV equipment (FLA = 420 Amps) so the cost of the low voltage equipment will not increase.

 

[Okpower]

My comments and conclusions after i read your comments:

dpc, Zogzog, slavag: I have to find prices of 115 KV equipment (is very close to the Plant, 300 mts). And I have to evaluate the construction of a 13.8 KV, 5 Kms line to the Plant. But really, i think the 115 KV is the expensive option.

ScottyUK, rcwilson: the conceptual stage is finished. We will start Basic Engineering the next week. Some of the work is done. According conceptual engineering, there will be two incoming lines with 2 XRF´s (5 MW each, total 10MW) for normal operation.

Looks like cost engineers will have a lot of work to do. Specially now, with a world financial crisis. All prices are expected to rise.

Thanks to all

 

[newpower]

I agree with everyone - finding a transformer that size is not a problem, but go with at least a 10 MVA and definitely check your power factor!

Economic considerations are your main concern with supplying at 115kV.