Answer / raman jain

The Alternator shows small voltage when running on rated
speed and without excitation. This is due to the remanent
magnetization of the core of Alternator. After new winding
and insulation, the remanent magnetization no longer exists
and that is why it does not shows any voltage.
After initial voltage built up it attains the remanent
magnetization again.

What is the need of earthing transformer for delta side of a transformer. (Think of a line section between a star/delta transformer at a grid substation and delta/star transformer at a village. An earthing transformer is there at the delta side of the star/delta transformer at grid substation). As there are no ground reference there will not be fault current if a one phase is grounded. Further L-L phase will be sensed by the primary side of star/delta transformer as a L-G fault. So why an earthing transformer is required at delta side

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