Minimum rating of oil cooled transformer

[power2020]

Dear Folks,
what is the minimum rating of Distribution transformer (11/0.415kV) requires to provide oil sump? And which standard gives this information.
Advanced thanks for your information.

 

[RRaghunath]

Look in NFPA. I remember the stipulation is not based on transformer rating but on oil quantity, if oil quantity exceeds 2000 litres, sump needs to be provided.