Abstract
The vibrations generated by a three-phase power transformer reduce the comfort of residents and the service life of surrounding equipment. To resolve this tough issue, a quasi-zero-stiffness (QZS) isolator for the transformer is proposed. This paper is devoted to developing a QZS isolator in a simple way for engineering practices. The vertical springs are used to support the heavy weight of the transformer, while the oblique springs are employed to fulfill negative stiffness to neutralize the positive stiffness of the vertical spring. Hence, a combination of the vertical and oblique spring can yield high static but low dynamic stiffness, and the vibration isolation efficiency can be improved substantially. The dynamic analysis for the QZS vibration isolation system is conducted by the harmonic balance method, and the vibration isolation performance is estimated. Finally, the prototype of the QZS isolator is manufactured, and then the vibration isolation performance is tested comparing with the linear isolator under real power loading conditions. The experimental results show that the QZS isolator prominently outperforms the existing linear isolator. This is the first time to devise a QZS isolator for three-phase power transformers with heavy payloads in engineering practices.
Highlights
To reduce the noise radiation of the transformer, some vibration isolation methods have been developed in recent years [10]
Gu et al [11] utilized a single-layer-spring device for vibration and noise reduction of the transformer, and the results showed that the device can effectively reduce the noise radiation of the transformer, except for low-frequency vibration
Zhou et al [50] and Wang et al [51] proposed the mutually repelling permanent magnets and vertical spring to protect the infant from the vibration of the ambulance, but the QZS isolator has never been applied for vibration isolation of the three-phase power transformer yet
Summary
E schematic diagram of the QZS isolator without payload is shown, where the oblique and vertical spring is of original length. Erefore, the effects of the force amplitude and damping on the vibration isolation performance are discussed. Erefore, the smaller the excitation amplitude is, the lower the jumping-down frequency is and the wider the frequency band for effective vibration isolation is. Erefore, it can be inferred that if the damping ratio continues to increase, the resonance peak will completely vanish
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