Earth Fault Tripping of Dist. Trafo (2.5MVA) During First Energization at Site

We have attemped to charge the first dist. Tranfo(2.5MVA, 6.6/0.433kV) Trafo. Having ABB numerical relay setting as below :

Attempt-1:

50N (E/F Inst.) = 10%, 50ms

Inrush. Setting = 20%, 100ms

Result : IMMEDIATE TRIPPED ON E/F

Attempt-2:

50N (E/F Inst.) = 10%, 50ms

Inrush. Setting = 20%, 150ms

Result : IMMEDIATE TRIPPED ON E/F

Attempt-3:

50N (E/F Inst.) = 10%, 50ms

Inrush. Setting = 20%, 200ms

Result : IMMEDIATE TRIPPED ON E/F

Attempt-4:

50N (E/F Inst.) = 10%, 100ms

Inrush. Setting = 20%, 200ms

Result : IMMEDIATE TRIPPED ON E/F

Request you to kindly guide further line of action.

6.6 HV Panel Tranfo. O/G Panel to Dist. Tafo. HV Side Cable Meggered and found OK, Trasfo. Secondary to 0.415kV LV Panel LV Busduct Meggered and found OK.

Quick relay highly appreciated.

Regards,

T.D.