Clamping pressure during step loading of power transformer with and without prior energisation

Dynamic load conditions induce enhanced mechanical stress on insulation systems, potentially causing degradation
over time and compromising the transformer's short-circuit withstand capability. Thermal expansion of the windings,
occurring as the transformer is loaded, increases the pressure. Conversely, core losses and tie plate expansion contribute to a
reduction in pressure. This paper presents the effect of step changes in core losses and copper losses by on-line measurements
of the clamping pressure, to better understand the mechanical stresses acting upon the cellulose materials.