Transformer terminal accidents have occurred, but there is a growing trend. From the transformer terminal accident analysis point of view, the short circuit ability is not enough to become the leading cause of power transformer accident, caused great harm to the grid, seriously affecting the safe operation of power grids.

Transformer terminal often occur following the accident: external short-circuit many times the impact of coil deformation gradually, the final breakdown of insulation damage; frequent external short-term impact by short-circuit damage; long to short circuit the impact damage; a short circuit impact on the damage. The main form of transformer short-circuit damage are the following:

An axial instability. This damage is mainly axial electromagnetic force generated in the radial magnetic flux leakage, leading to the transformer winding axial deformation.

2, bending up and down the line cake. This damage was due to the wire between the two axial pad under the action of the axial electromagnetic force, because the moment had to produce permanent deformation, usually between the two cake deformation is symmetrical.

3, the winding or wire cake collapse. This damage was due to the wire under the action of the axial force, mutual compression or impact, leading to tilt deformation. If the wire the original slightly tilt, the axial force to promote the tilt increases, serious collapse; wire aspect ratio, the more easily lead to collapse. End of the leakage magnetic field in addition to the axial component, there is the radial component, the inward turn of synthetic electromagnetic force generated by the two direction of the magnetic flux leakage resulted in the winding wire, outer winding flip out.

Winding rise to platen distraction. This transformer terminal damage is often because the axial force is too large or the existence of its end of support strength, stiffness is not enough or assembly defects.