Electrodynamic faults: which occurs between insulation and current carrying conductors, HV and LV winding due to external and internal short circuits
Electromagnetic faults: Which occur due to eddy currents induced in the magnetic circuits or the clamping structure.
Electrical faults which occurs due to bad contacts in the leads or bad contacts in the tap changer Dielectric faults: Which occur due to shorting between windings or between live parts and earth, partial discharges
Thermal faults: Which occurs due to abnormal temperature rise, hot spot, thermal ageing or pollution in transformer oil
Mechanical faults: Which occur due to vibrations, leakages or defective operation of the tap changers