General

Question 1

Advantages of delta star transformer?

Answer 1

1) Line to ground fault occurring in secondary does not go to primary so no need set a ground setting for upstream breaker
2) isolation from harmonics
3) protection from zero sequence current

Question 2

Delta star transformer cannot be parralled with

Answer 2

with star - star or delta-delta transformer because in delta star connection secondary line voltage leads primary line voltage by 30 degree