• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.49-53
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• 2008

This study deals a way to reduce the transformer noises. The first step is to identify the source of the transformer noises. The second step is obtaining the vibration characteristics of transformer; its natural frequencies and mode shapes. Based on these information, an method to reduce the vibration of transformer can be found. The cause of transformer noises is mainly due to the magnetostrictive vibration of a core which is made of ferromagnetic substances. It is well known that the magnetostrictive vibration of a core is unavoidable, and a way to reduce the transformer noise by structural design is needed. It requires understanding the vibration characteristics. The natural frequencies and the mode shapes of transformer are analyzed by performing the modal testing.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.781-789
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• 2018

This paper proposes a new approach utilizing empirical mode decomposition (EMD) reconstruction to process vibration signals of a transformer under DC bias caused by high voltage direction transmission (HVDC), which is the potential cause of additional vibration and noise from transformer. Firstly, the Calculation Method is presented and a 3D model of transformer is simulated to analyze transformer deformation characteristic and the result indicate the main vibration is produced along axial direction of three core limbs. Vibration test system has been built and test points on the core and shell of transformer have been measured. Then, the signal reconstruction method for transformer vibration based on EMD is proposed. Through the EMD decomposition, the corrupted noise can be selectively reconstructed by the certain frequency IMFs and better vibration signals of transformer have been obtained. After EMD reconstruction, the vibrations are compared between transformer in normal work and with DC bias. When DC bias occurs, odd harmonics, vibration of core and shell, behave as a nonlinear increase and the even harmonics keep unchanged with DC current. Experiment results are provided to collaborate our theoretical analysis and to illustrate the effectiveness of the proposed EMD method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.346-348
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• 2002

This paper analyze spectrum of vibration-frequencies to reduce noise level of distribution transformer. Using loading back method on same condition of a real load to grasp the effect of core and winding which are caused by the transformer vibration. we were measured the vibration-frequency by varing applied voltage and load current of a transformer. The major cause of a transformer vibration is occured by the harmonic effects, and was identified that the vibration is less influenced by the coil. As the result of this paper, comparing the transformer with some isolated material with the general transformer the transformer with some isolated material could reduce spectral amplitude of vibration-frequencies.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.697-700
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• 2003

This paper presents design and analysis of step-down piezoelectric transformer for application to AC-adapters. These transformers are consist of rectangular type and disk type multilayered piezoelectric ceramic plate. This piezoelectric transformer operated in third thickness resonance vibration mode. Finite element methode(FEM) was used for analysing transformer. Vibration mode and electric field of piezoelectric transformer were simulated at resonance frequency. As results, rectangular type transformer's output voltage was higher than the disk type. But disk type transformer's current was lagger than rectangular type. These results are assumed that disk type transformer's mixed vibration mode influence transformer's output characteristics. From these results, we expect that disk type piezoelectric transformer is more adoptable than rectangular plate type piezoelectric transformer for AC adapters.

• 한국안전학회지
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• 제15권1호
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• pp.106-111
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• 2000

EP(Electrostatic Precipitator) has been used to keep the natural environment from fly-ash in the industrial fields and operated in intermittent PEC(Pulse Energized Control) mode to improve dust-collecting efficiency. Intermittent PEC mode induces low-frequency harmonic currents into power system, therefore EP transformer vibrates. This continuous transformer vibration developes transformer abnormal audio-noise and if it is too much or operates in the region of natural frequency, transformer will be damaged in the end. EP interruption caused by transformer damage results in power generation stopped, power quality down and economic loss. Therefore, this paper explains harmonic currents and transformer vibration-core vibration, winding vibration, and proposes the measures of suppressing the vibration with EP operated in intermittent PEC mode. And this results is proposed to be used for future EP transformer design or EP control method to operate EP-concerned equipment safely keeping from system faults caused by transformer vibration.

• 조명전기설비학회논문지
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• 제26권10호
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• pp.52-59
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• 2012

In this paper, The cast resin transformer's vibration is measured using noncontact raser vibrometer(LV110D). The vibration characteristics of transformer windings and core are analyzed for relation between vibration magnitude and cause. Using the analysis results, the technique is presented to diagnose cast resin transformer. which is able to diagnose transformer' deformation in winding and core geometry. The magnetostriction and electromagnetic force act on the core and windings, causing them to vibrate. The vibration from windings and core penetrates into transformer cast resin and reaches the outside walls. The fundamental frequency of the core and windings vibration signal is twice that of the power frequency(120Hz). The results show that the magnitude of core vibration is linear to driving voltage amplitude and magnitude of windings vibration is increased to loading current under the some level and then stabilized.

• 조명전기설비학회논문지
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• 제23권3호
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• pp.30-37
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• 2009

The majority of the causes for the failures of power transformers in operation are mechanical defects due to vibration. The vibration phenomenon was measured from the power transformers in operation in the substations. The vibration measurement was performed in a $6{\times}4$ structure on one side of each transformer. The vibrations of the measured points were presented in two and three dimensions and analyzed. The results, according to the elapsed year of the transformer and the load capacity to the transformer, were analyzed. These results could be used as basic data with which to establish vibration standards for power transformers. In addition, the load capacity-vibration phenomenon correlation was examined and regression analysis was performed to derive the estimation function. The vibration phenomenon according to the elapsed yeah was also estimated to derive the function. Then the analysis of the power transformers was used to set vibration standards for them based on the vibration data.

• 전기학회논문지
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• 제61권7호
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• pp.992-997
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• 2012

In this paper, we were analyzed the vibration characteristics of the three-phase cast resin transformer using less than 50% of load in the field. Most of the cast resin transformer is less than 50% in the domestic field is used for load conditions. Consisting of a solid insulator cast resin transformer is generating lots of noise and vibration. In addition, because it is affected by Joule 's heat is used in light load conditions. As a results, the transformer vibrations at frequencies below about from 200Hz to 500Hz were detected. Vibration velocity depends on the load variations were found. Load up to approximately 20-30% in most cases the vibration velocity was found at 4,000 ${\mu}m/s$ or less, 8,000 ${\mu}m/s$ or more. Vibration frequency at light load conditions were generated at the 120Hz, 240Hz, 360Hz and 480Hz. At the load condition of from 10% to 20%, vibration velocity is higher than another. Most of the vibration velocity were identified at the 1,000 ${\mu}m/s$ or less. Using the vibration frequency and velocity measurements data, the load on the cast resin transformer analyzed the correlation of the burden. Therefore, this data could be found in the vibration characteristics of the light-load conditions. If the field measurements using the data perform diagnostics on the transformer, it's expected to be very effective.

• 전기학회논문지P
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• 제58권2호
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• pp.172-177
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• 2009

Most of the causes of the failures of power transformers in operations are mechanical defects due to vibration. To identify these causes, the vibration phenomenon was measured from the power transformers in operation in the substations under the Daejeon power transmission district office of KEPCO. The measurement was performed in a 6${times}$4 structure on one side of the transformer. The vibration of the measured points was presented in 2D and 3D, and analyzed. The results according to the period in use of the transformer and the load applied to the transformer were analyzed. These results will be used as basic data to establish the vibration standard for the power transformer, In addition, with a load capability and vibration phenomenon correlation and regression analysis to identify by way of function was reached. And the vibration phenomenon pass a years with changes and to analyze correlation, was estimated to bring in the function. And then through the analysis of power transformers to set standards based on vibration data was used to.

• 조명전기설비학회논문지
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• 제26권4호
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• pp.75-81
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• 2012

In this study, vibration characteristics in according to the load type of cast resin transformer using vibration measurement device were compared. Measurement conditions are the same installation and operation of the three-phase cast resin transformer. If the load increases in transformer using the rotating machinery, the frequency is growing. In the transformer using the lighting and heating loads, it's detected the 55 [${\mu}m/s$] in or outside and 120 [${\mu}m/s$] or more at 60[Hz], the 30 [${\mu}m/s$] in or outside at 120[Hz], and the 70 [${\mu}m/s$] in or outside at 420[Hz]. When increases the loads, it's appeared the 60 [${\mu}m/s$] or less at 450[Hz] or more in rotating machinery, but the velocity of lighting and lighting loads are appeared from 5[${\mu}m/s$] to 115[${\mu}m/s$] inside the 420[Hz] in the same load condition of 20[%]. Through this study, it's verified that there are differences the internal vibration in according to the type of load in cast resin transformer.