Back Enegize of Transformer

[sky72]

Can we enegize a 240MVA 275/132kV step up transformer under no load condition by using the 132kV source due to 275kV incoming line is not ready.

The 240MVA transformer will put under "soak" condition.

BTW, can we use a step up transformer as a step down transformer?

Thanks.

 

[cuky2000]

It is possible to energize the transformer from the low side. Make sure your protection system support that and may be a good idea checking with the manufacturer for advise and guaranty issues.

 

[slavag]

Hi Sky72.
Why not?
It's normal operation condition.
In additional please see.
thread238-192000
Best Regards.
Slava

 

[ScottyUK]

In principle, yes to both questions. You may find the LV side protection does not respond well to the inrush and may trip on energisation.

If you have a differential scheme - quite likely on a transformer that size - make sure it can trip the LV breaker. Often it trips the HV side which then inter-trips the LV side. A soak test is definitely one of those times when you want the diff scheme (or REF on a star winding) operational as it operates quickly and will minimise damage from a fault.


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Sometimes I only open my mouth to swap feet...

 

[slavag]

Hi.
In additional. I think we have good discussion about inrush currents in case of LV or HV energazing, but forgot when.

Sky72, cuky2000 are right, ask trf, manuf
Regards.
Slava

 

[TurbineGen]

I agree with Scotty with the relay settings. You might need to adjust them if using the transformer as a step-up unit. As long as you don't exceed the rated MVA rating of the transformer, using as a step-up should not hurt it. We do this all the time for our pumped-storage facilities. We use the transformers as step down for pumping and then stup up when we drain for generation. MVA rating is the same regardless of the direction of power flow.

-TurbineGen

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