Surge admittance

Surge A rapid rise in current or voltage, usually followed by a fall back to the normal value. Susceptance The reciprocal of reactance, and the imaginary component of admittance, expressed in siemens. 

Surge impedance Zq and surge admittance Yq in these equations are extreme values of the characteristic impedance and admittance in Equation 1.49 for frequency f oo. 

Earth-return impedance has been well discussed, and its effect on the wave-propagation characteristic and the transient waveform is well-known, as is clear from a number of publications. Earth-return admittance [8,9,39,40], however, is neglected in most studies on wave propagation and surge characteristics, and its significant effect is not well understood [8,9,40, 41, 42 3]. 

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