基于典型振动规律的干式变压器机械状态诊断

Electrical, thermal, mechanical, and rther stresses ailing together on dry-type transformer may lead to core loos en ings, winding deformations, and other faults, the vihration-hased analysis method ran sensitively reflect the mechanical state of the fore and windings. Thus.it is suitable for the mecltanical fault detection of dry-type transfamers. In this paper,a finite element model of the dry-type transformer is constructed.and its vibration mechanism and characteristics are investigated hy simulation. The simulatioi results show that.at normal operation.the winding vibration is much smaller than the core vibration caused hy the magnetostrictive effect. A dry-type transformer experiment platform is built.and then the vihration signals of the transformer are measured and analyzed at normal and mechanical fault states. Experimental results show that with the gradual magnetic saturation of the iron core, the vihration signal is no longer linearly related to the squared voltage. Moreover.the peak value of the total vihration signal grows rapidly and the amplitude of the fundamental frequency vihration signal increase slowly. The vihration signal spectrum of the dry-type transformer under different operating conditions is measured. Experimental results show that the ratio of fundamental frequency to total and high frequency to low frequency can he used to diagnose the mechanical state of dry-type transformers.