why the autotransformer burnt while stating the pumpmotor?,
In starter and motor there was no abnormality.
Answer Posted / amit kumar singh
The one reason may be that at the time of starting,
induction motor sucts very high inrush current for the
establishment of magnetic field. Thus the total MVA
requirement at the time of motor starting is about 6 to 7
times the rated MVA of motor (if voltage is considered to
remain constant at the time of starting).
As, a transformer can only withstand 1.5 times its rated
MVA (i.e. also only for short duration), the heavy
requirement of MVA by motor could have damaged the
transformer (in case of failure of tap changer operation to
reduce voltage applied before starting of motor).
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