I.$$ A $3-$phase, $400$kVA, $50$Hz$,$ star connected alternator has an armature DC resistance of $1$ as measured by an AVO meter when connected across its two line terminals. An excitation applied to the alternator under open$-$circuit produces $90$ volts with the short$-$circuit current for the same excitation being $72$A$.$ The alternator is connected to the load through a feeder having resistance of $1\mathrm{.}5$ and reactance of $2$ per phase. The load draws $100$A at a power factor of $0\mathrm{.}8$ lagging with $11$kV maintained. Find the regulation of alternator for the given loading conditions.

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