Synchronous Generator

Discussion in 'Homework Help' started by gemignat, Mar 31, 2009.

  1. gemignat

    Thread Starter New Member

    Mar 31, 2009
    A 3 phase, 2300V, 100kVA, 60Hz, 6 pole sync. generator has stator reactance 7.9 ohm & magnetising reactance 56.5 ohm. Winding resistance neglible. Immediately after machine synchronised on bus, field current=23A, power input at prime mover = 3.75kW.
    a) Determine Field current when generator supplying rated output at 0.9 lagging power factor?
    b) What is Internal torque developed by machine when delivering output current of 15A and field current=20A?
    c) what is power input at shaft required to drive machine out of synchronism at 20A field current?

    Please can anyone help? I've been stuck on this question for a couple of weeks now!
    Last edited: Mar 31, 2009
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009

    Just a couple of questions before I think about the problem.

    1. Is it assumed that the generator open circuit output emf changes linearly with field current adjustments? This is often a non-linear relationship and requires some graphical data to determine the corresponding values.

    2. Do you have (textbook ?) answers for the for the questions?

    3. What answers have you obtained thus far and by what methods?