EE 301 HW#37
AC Generators Part II
la.) For a 4 pole, 60 Hz generator, determine the speed in rpm of the rotor:
b.) For a 2 pole rotor operating at 7200 rpm, determine the frequency of the electrical signal.
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c.) How many poles would a generator need if it operated at half the rotor speed of problem
(1 b), bllt produced the same frequel1cy?
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2) Given: At a hydroelectric plant on the great Coilimbia River, a 3-phase, Y-connected
synchrol10us generator is rated at 300 MVA, 60Hz and 25KV. It operates with a lagging power
factor of 0.75 and negligible armature resistance and reactance. Use Van as the voltage reference.
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a) Fil1d the line current phasor I a . (This would include the angle!).
b) Draw the p"ower conversion diagram.
c) If there are no mechanical losses, find PIN. What is the efficiency of this generator?
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EE 301 HW#37
AC Generators Part II
'3) Given: A Y-conl1ected, 4-pole, 3-phase, 2.2 KV, 60Hz synchronous generator with 0.060 per
phase resistance supplies rated line voltage/current to a Y connected load with a 0.85 lagging'
power factor. The power Ollt is 1.492 MW. The nlechanicallosses are 92KW. Use Van as the
voltage reference
Reg'd:
a) Find Ia (pha-sor).
b) What is the effiCie~Cy. of t.he generator? . .
c) Draw the power conversion diagram.
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d) At what speed does the shaft rotate (rpm)? /
e) What is the prime mover tor:que?
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