Distribution Transformer Transformer Voltage Unbalance

respacted friends this transformer secondry star winding neutral not grounded since 2007. also in my side like that same capacity more transformer not grounded.

1000kva 13.8kv/0.4 kv 3phase Delta/star distribution transformer

Dear respected friends in my network transformer as i mention above, their is problum between neutral & earthing appearing 220vac actually it must be ov, in this case neutral not bonded since 2007. also like that i have lots of transformer in my site at diffrent location, their is no problum only one transformer i faced as above mention.

between phase to phase 400vac, is normal

phase to neutral 220vac , is normal

Earth to neutral 220vac, that is completly abnormal

and Earth to L1, Phase=180 Earth to L2, Phase=250 Earth to L3, Phase=248

also if we will check by 220vac screw driver tester,as in neutral full lamp light appearing, and Phase L1, light Not Appearing, But another L2 & L3 Light Appearing.

please if someone have answer so help me, because my suspect of transformer secondry star winding neutral left inside, so must be replaced transformer or what please reply.