Discussion
A machine whose direct-on-line starting current is 300 A is started star-delta. The line current at starting becomes
Answer: C
Correct answer: 100 A
Star-delta starting reduces the line current to one third of the direct-on-line value:
\[ I = \frac{300}{3} = 100 \text{ A} \]The 173 A figure would be \( 300/\sqrt{3} \), which accounts for the winding voltage reduction but forgets that the line and phase currents are also related differently in the two connections.
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