1) Multiple external short-circuit shocks cause the coil to deform gradually, with most cases resulting in insulation breakdown and damage.

2) Frequent short-circuit shocks damage externally in the short term.

3) Damage due to prolonged short-circuit surges

4) Damaged by a single short circuit surge.

3 Main Forms of Transformer Short Circuit Damage

In recent years, transformers have suffered damage due to export short-circuit incidents. When transformers experience short-circuit faults, their damage typically exhibits the following characteristics and causes.

3.1 Axial Instability

This type of damage is primarily caused by the axial electromagnetic force generated by radial magnetic leakage, leading to axial deformation of the transformer windings, accounting for 52.9% of all damage incidents.

3.1.1 Line Cake Upper and Lower Curvature Deformation

The damage is due to the wire between the two axial shims, under the action of the axial electromagnetic force, undergoing plastic deformation due to excessive bending moment. Typically, the deformation between the two disks is symmetrical.

3.1.2 Winding or bobbin collapse

This damage is due to the wires being compressed or collided under axial force, resulting in tilting deformation. If the wires are originally slightly tilted, the axial force promotes further tilting, which can lead to collapse when severe; the larger the height-to-width ratio of the wires, the more prone to collapse it becomes.

The end leakage magnetic field, in addition to the axial component, also includes a radial component. The combined electromagnetic force generated by the leakage magnetic fields in both directions causes the inner winding wires to flip inward and the outer winding wires to flip outward.

3.1.3 The winding升起will open the pressure plate

This damage is often due to excessive axial force, insufficient strength or rigidity of the end support components, or assembly defects.

3.2 Radial Instability

This type of damage is primarily caused by the radial electromagnetic force generated by the axial magnetic leakage, leading to radial deformation of the transformer windings, accounting for 41.2% of all damage incidents.

3.2.1 Insulation damage due to elongation of outer winding wire

Radial electromagnetic force attempts to increase the diameter of the outer winding, and excessive tensile stress on the wire can cause plastic deformation. This deformation often leads to wire insulation damage and inter-turn short circuits, which can severely cause the coil to collapse, become tangled, and even break.

3.2.2 Winding end reversal transformation

The end leakage magnetic field, in addition to the axial component, also contains a radial component. The resultant electromagnetic force produced by the leakage magnetic field in both directions causes the winding conductors to flip inward, and the outer winding to flip outward.