Backcharging from 400KV

[Devendra Kumar]

What can be the methods to back charge the Unit Aux transformer through 400KV in a Hydro Power plant.

 

[RRaghunath]

First step is to ensure the Generator Terminal Circuit Breaker (CB) and associated Disconnector open. Then ensure MV Circuit breaker of the UAT incomer to the MV Auxiliary Switchboard is open.
Then, close the 400kV CB at the HV terminals of the Generator Step Up Transformer (GSUT) and see GSUT as well as UAT get energised.
Then, the UAT MV incomer can be closed after necessary Synchrocheck with the existing incomer from Station MV transformer.

 

[Devendra Kumar]

Thanks

 

[prc]

Is it a normal hydro or pumped storage? Is there a breaker between GSU and generator?

 

[Devendra Kumar]

Normal Hydro Plant. There is no breaker b/w GSU & Generator.

 

[crshears]

In the steam plant where I worked, there were removable links between the MOT and the generator, specifically provided to allow back-potting of just the MOT from the grid.

CR

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

 

[prc]

Back-charging of generator transformers can create problems. You must keep the generator protection arrester and surge absorber at the LV terminals to mitigate the transferred surges from the 400 kV side.