Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Magnetisation Curve (Synchronous Machines)

  1. Oct 23, 2013 #1
    Hi All,

    Today I conducted a lab in which we plotted the open circuit voltage (V[oc]) and closed circuit current (I[sc]) versus the excitation current in the rotor (I[x]).

    From the data (plots are attached to thread), it can be seen that saturation occurs in the V[oc] versus I[x] curve however the I[sc] versus I[x] curve remains linear.

    Why is it that saturation occurs only with V[oc] and not with I[oc] in the stator?
     

    Attached Files:

    • Voc.png
      Voc.png
      File size:
      2.9 KB
      Views:
      69
    • Isc.png
      Isc.png
      File size:
      2.6 KB
      Views:
      57
  2. jcsd
  3. Oct 24, 2013 #2

    gerbi

    User Avatar
    Gold Member

    Open-circuit curve (stator voltage vs excitation current) test is performed (or calculated) at zero stator current and 0-1,2 of rated stator voltage. In this case saturation of magnetic circuit is clearly visible.

    Short-circuit curve (stator current vs excitation current) test is performed at shorted stator terminals 0-1.0 of rated stator current. Stator voltage (internal stator voltage) is quite low during the test, so you wont observe effects of saturation.

    So why saturation is dependent on voltage ? Remember that equation: E=4,44*f*ψ*z
    where: E-voltage (stator), f-freuqency, ψ-magnetic flux, z-number of turns

    Frequency is static, numer of turs also. Only voltage and flux chanches, so: E≈ψ
    The higher voltage, the higher flux is required. Higher flux means higer saturation.
     
    Last edited: Oct 24, 2013
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Magnetisation Curve (Synchronous Machines)
Loading...