Megger frax 101 - Page 53

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FRAX Software
© 2011 Megger Sweden AB
)0()1()0/1( ChPhaseChPhaseChChPhasePhase
SFRA (Linear)
0/1 ChChMagnitude
)0()1()0/1( ChPhaseChPhaseChChPhasePhase
Impedance
Ch1)/Ch1-(Ch0*50 Ch1)/I-(Ch0 U/I Z
Phase(Z) Phase
Admittance
Ch1))-(Ch0*Ch1/(50 1/Z Y
Phase(Z)- )( Phase YPhase
Two additional models are available and that is R and L model that plots its results in
Impedance view. The R and L models are very useful evaluate why curve deviate at low
frequencies in short-circuit measurements, increase of R at lowest frequencies may be a poor
contact, change of L may be winding movement. Also comparing R when frequency increase,
typically in the range 50-400 Hz may give valuable information; this is also called FRSL
(Frequency Response of Stray Losses)
To create a custom model, check Custom Model in the Models dialog as shown above and
click OK. Then, click the button named "..." in the Custom Model frame in the main window.
This brings up a window called Model Options.