If a line is 100 % series compensated it may result in series resonance at power frequency of
Right Answer is:
50 or 60 Hz
A line with 100% series compensation would have a resonant frequency equal to the power frequency, and since the damping in power systems is low, such a system would be hypersensitive to small changes. For this reason, the degree of series compensation is limited in practice to about 80%. The circuit would series resonant at fundamental frequency i.e 50 or 60 Hz.