Generator step up transformer - 1600KVA, 400/11000v 1

[6364RMFM]

We are currently installing a power house with 5x1250KVA,400V synchronized generators. One of the loads to be fed from this power house is 1600KVA,400V and is 1500m from the power house. We intend to put up a 1600KVA generator step up transformer (400V to 11KV) at the power house and run 1500m of XLPE 11KV cable to the load site. At the load site we want to put up the 1600KVA, 11KV/400V stepdown trasnsformer to fed the load. Please advise on the set up of the two transformers and the associated switchgear. Who are some of the suppliers for generator step up transformers?

 

[FreddyNurk]

I assume you're in an IEC standard area as opposed to IEEE.

Selection of the transformers (and indeed, to a fair extent, the generator voltage) really depends on how you want to protect it.

For our power stations (similar, though I'd probably not do 5x1250kVA at LV for ours) we run a YNd configuration for any step up feeders, with a star point CT to detect any earth fault on the high side. I don't get involved in the load side though, although for our distribution they're typically Dyn configuration.

Another fair option (though its likely the alternators are on the small side for 11kV) would be to generate at 11kV and feed out, depending on how you want to manage the switchgear and generators (and how you protect them).

A location would help greatly in commenting on suppliers for switchgear and transformers.

 

[6364RMFM]

The location is the Middle East. On MV we would use 400V breakers and for the 11KV use Ring Main Unit.

 

[GEORGE2311]

If i was you, i would choose the generator trafo to be Δ in generator side in order to trap currents caused be asymmetries (I2) and the third harmonic caused by the non linear B-H characteristic of the transformer core. The other side is preferred to be Y solidly or earthed via impedance (that depends on your design) in order to apply easy protection schemes and avoid over-voltages and surges. The step down transformer then should be Δ in the MV and Y in the LV side preferably solidly earthed, in order to have clear ground fault schemes in MV and distribution with neutral in LV.

G.F.

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