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Alternator Problems (3 phase and single phase AC Motor)

  1. Mar 1, 2008 #1
    1. The problem statement, all variables and given/known data

    1. A 4MVA, 13.3kV, 60Hz, 3 phase, delta-connected alternator has an effective resistance of 5.2 ohm/phase and a combined armature reactance of 54 ohm/phase. Determine the full-load generated voltage per phase, a. At unity pf, b. at 0.8 pf lagging, and at 0.866 leading pf.

    2. A 750kVA, 2300V, delta-connected, 3-phase alternator has had open and short circuit tests performed and the following date were obtained:

    Short Circuit test

    Field current = 31.5A
    Line current = rated

    Open-circuit test

    Field-current = 31.5A
    Line voltage=1050V

    The dc resistance across the terminals was measured at 0.38 ohm. Calculate the V.R. at 0.8pf lagging.

    3. Calculate the open circuit votlage of a 3phase, star-connected alternator, 4 pole, 60Hz, 120 slots with each slot having 6 conductors in two layers. The machine is running at 1800rpm with a flux per pole of 125 milliWeber. The coil span is 12.

    4. A single phase alternator, 50kVA, 460V supplies the rated load at 0.88 pf lagging. The dc resistance across the terminals ais 0.5 ohm and the synchronous reactance is 2.5 ohm. Calculate the angle of the power.

    2. Relevant equations

    3. The attempt at a solution

    I have completely no idea on how to solve these problems...

    I don't need the direct answers, I just want you guys to help me solve it, more on the procedure of solving it. Suffice to say, i want you guys to guide me in solving these problems.
  2. jcsd
  3. Mar 2, 2008 #2

    you know, i'm also wondering how to solve this exact 4 questions..

    are you my classmate or something?!

    i hope someone solves this ASAP.. coz i'm really desperate.. i need the solutions by tom.. :cry:
  4. Nov 24, 2011 #3
    1. Find the number of armature conductors in series per phase required for 3 phase, 10 pole alternator when driven at a speed of 600 RPM. Armature has 90 slots and armature winding is star connected to give induced emf of 11KV between lines. Assume flux per pole as 16 mwb?
  5. Nov 24, 2011 #4
    hey guys plz help me in above problem...
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