Nonlinear Oscillation in Potential Transformers Connected Controlling Circuit

In this work at first ferroresonance phenomenon is introduced and then various type of ferroresonance overvoltages in a potential transformer is simulated. Then effect of neutral earth resistance on controlling these oscillations in the case of nonlinear core losses has been studied. Core losses in the potential transformer are modelled by third order power series in terms of voltage and include nonlinearities in core losses. It is expected that neutral earth resistance generally can cause ferroresonance 'dropout'. For confirmation this aspect Simulation has been done on a one phase potential transformer rated 100VA, 275kV. The simulation results show that connecting the neutral earth resistance on the system configuration, shows a great controlling effect on ferroresonance oscillation.