A circuit of 500 V for single-phase asynchronous motor has synchronous impedance of 3.2 Ω. The armature resistance is 0.3 Ω. Determine the induced emf if the machine develops 31.3 kW and the mechanical losses equals 4 kW
"E= \\sqrt{(V \\cos \\phi+IR)^2+(V \\sin \\phi+IX)^2}\\\\\nE= \\sqrt{(\\frac{500}{\\sqrt3}+IR)^2+(IX)^2}\\\\"
Input power
"4 kW +31.3 kW\\\\\n35.3kW"
"35.3kW= \\sqrt3 VI \\cos \\phi\\\\\nI= \\frac{35.3*10^3}{\\sqrt3 *500}*40.76A\\\\\n\\implies E_{phase}= 327.94 V"
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