Shake Table Testing of a Base-isolated Transformer Bushing System

In order to solve serious damages of large-scale transformers in recent earthquakes, shaking table test on a base-isolated transformer-bushing system was conducted using a hybrid isolation system. Base isolation design and arrangement for the transformer-bushing system were implemented by the hybrid isolation system consisted of laminated rubber bearings and sliding bearings. Moreover, shaking table test on the base-isolated transformer-bushing system to white noise and Wolong, Qingping, Zengjia ground motions recorded in the great Wenchuan earthquake was conducted. Dynamic properties and earthquake responses of the system were measured. Meanwhile, the seismic responses of the base-isolated transformer-bushing were compared and analyzed with the non-isolated system. The results show that acceleration and strain responses of the base-isolated transformer-bushing system can significantly be reduced to less than 1/2 of those of the non-isolated system. Relative displacement responses of the base-isolated system to the table will increase to some extent, however, acceleration of 0.4g table motion is within 60 mm when the system to the peak. The hybrid base-isolation system can reduce ground motions transferring to the transformer-bushing system, filter out high frequency components of the earthquake motions, prevent quasi-resonance between transformer-bushing system and earthquake motions, and mitigate earthquake responses of the transformer-bushing system. The tests validate the effectiveness of the hybrid base-isolation system for a transformer-bushing system, therefore, the hybrid system base-isolated transformer can meet the design demands of lowering one-degreee earthquake fortification intensity. © 2017, High Voltage Engineering Editorial Department of CEPRI. All right reserved.