• Title/Summary/Keyword: ultrasonic inspection

Search Result 455, Processing Time 0.049 seconds

Detection of the Ultrasonic Signals due to Partial Discharges in a 154kV Transformer

  • Kweon, Dong-Jin;Chin, Sang-Bum;Kwak, Hee-Ro
    • KIEE International Transactions on Electrophysics and Applications
    • /
    • v.2C no.6
    • /
    • pp.297-303
    • /
    • 2002
  • We have developed an on-line ultrasonic detector to monitor partial discharge in an operating transformer. The ultrasonic sensor has 150[KHz] resonance frequency and contains a pre-amplifier with 60[㏈] gain. The on-line ultrasonic detector has 50~300[KHz] frequency band-pass filter to remove electrical and mechanical noises from the transformer. This detector has an ultrasonic signal discrimination algorithm which discriminates ultrasonic signals due to partial discharge in a transformer. A moving average method of ultrasonic signal number was employed to effectively monitor the increasing trend of the partial discharge. This paper describes an experience of partial discharge detection in a 154[㎸] operating transformer using an ultrasonic detector. With regards to gas analysis in oil, C2H2 gas was produced with a warning level in this transformer We detected ultrasonic signals on the transformer steel wall, and estimated the position of partial discharge. With further inspection, we found carbonized marks due to partial discharge on the supporting bolt which fastens the windings.

Review of Non-Destructive Evaluation Technologies for Rail Inspection (철도 레일의 결함 검출을 위한 비파괴탐상 기술)

  • Han, Soon-Woo;Cho, Seung-Hyun
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.31 no.4
    • /
    • pp.398-413
    • /
    • 2011
  • For railway safety, it is very important to detect damages of rails at their early stage because any undetected damage in a rail can break the rail and cause a serious railway accident. In this paper, several NDT applicable to rail inspections are described. Major damage types in rails are discussed first and the rail inspection technology using conventional piezoelectric ultrasonic transducers, which is widely adopted for damage detection of rails, is explained. Other NDT being researched or tested for rail inspection are also discussed as complementary technologies to the concurrent contact type ultrasonic inspection. Characteristics of each rail inspection technologies are evaluated in order to provide requirements for future development of a new rail inspection method.

Development of an Ultrasonic Inspection Technique for LP Turbine Rotor Disc (초음파를 이용한 저압 터빈 로타 디스크 검사 기술 개발)

  • Chang, H.K.;Cho, K.S.;Won, S.H.;Chung, M.H.;Cho, Y.S.;Hur, K.B.
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.17 no.3
    • /
    • pp.174-183
    • /
    • 1997
  • Turbine rotor disc consists of disc, bore, keyway, hub, and rim in which the typical defects are located. And these part of disc has very complicated geometry, therefore proper transducer selection, wedge design, fabrication, classification and evaluation of the signal identification are required. In this research, test block with the artificial flaws at keyway and boresurface parts have been used in order to establish the ultrasonic inspection technique for flaw detectability on disc. The analysis of the signals from the test blocks was performed. The wedges were designed according to the curvature from the discs. All the ultrasonic signals were collected and identified for evaluation. The ultrasonic inspection technique for the flaw-detection was established from this research. And it is proved that the result of this research can be applicable in the field inspection.

  • PDF

Development and Application of IoT-based Contactless Ultraosonic System (IoT 기반 비접촉 초음파 측정 시스템 개발 및 적용)

  • Kim, Jihwan;Hong, Jinyoung;Kim, Rrulri;Woo, Ukyong;Choi, Hajin
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.24 no.3
    • /
    • pp.70-79
    • /
    • 2020
  • The main objective of this research to develop an IoT based wireless contactless ultrasonic system (ICUS) and its application to concrete structure. The developed system consists of 16 mems, 2Mhz digitizer, amplifying circuit, FPGA, and wifi module, enabling to measure leaky surface waves from concrete specimens without physical coupling process and wires. Multi-channel analysis is performed to improve the accuracy of data analysis, and the velocity of leaky surface waves and acoustics are derived. Field inspection of railroad concrete sleepers is conducted to evaluate the performance of the system and to compare the results with conventional ultrasonic pulse velocity (UPV). As a result of the field inspection, UPV was limited to evaluate damages. This is because crack pattern of railroad sleepers is parallel to ultrasonic ray path and accessibility of the railroad at the field is disadvantageous to contact-based UPV. On the other hand, ICUS possibly detect the damages as reduction of dynamic modulus by up to 59% compared to non-damaged specimen.

Application of Water/Ultrasonic System for Interlacing Pattern of Fibrous Assemblies (섬유집합체의 교차구조를 위한 물/초음파 시스템의 응용)

  • Kang, Jeon-Young;Joo, Chang-Whan
    • Proceedings of the Korean Fiber Society Conference
    • /
    • 2003.10b
    • /
    • pp.122-125
    • /
    • 2003
  • Ultrasonic wave has three classes of applications such as communication, inspection, imagination and processing. In processing, ultrasonic is used web bonding for nonwovens with applications including floppy disks, medical devices and many automotive Part. The important components of ultrasonic system are power supply, converter, booster, hem, anvil roller, pressure system and hold time controller. (omitted)

  • PDF

Mobile NDT Inspection System Using Ultrasonic (초음파를 이용한 모바일 비파괴 검사 시스템)

  • Kwon, Seong-Geun;Lee, Suk-Hwan
    • Journal of Korea Multimedia Society
    • /
    • v.19 no.2
    • /
    • pp.105-111
    • /
    • 2016
  • In order to inspect the quality of spot welding, inefficient destructive test and NDT (non destructive testing) utilizing expensive foreign ultrasonic inspection are being conducted in the automobile production lines, but NDT will be difficult to be used in the domestic automobile production due to complexity of the waveform analysis and lack of mobility. In this paper, NDT system inspecting the quality of spot welding based on mobile network is proposed to complement drawbacks of the conventional inefficient destructive testing and NDT inspecting the quality of spot welding. Regardless of daily condition of NDT tester, the proposed NDT system can determine the quality of spot welding automatically and transmit the information of NDT quality to smart devices of field workers in real-time so that convenience of NDT and productivity of automobile production will be improved. Several specimens with a variety of welding quality was produced to evaluate the performance of the proposed mobile ultrasonic NDT system and the conventional foreign equipment, through this experiments, the proposed mobile ultrasonic NDT system indicate the superior properties compared to the conventional equipment in terms of convenience, productivity, and economic.

Development of Automated Non-Destructive Ultrasonic Inspection Equipment for Welding Crack Inspection (용접크랙검사용 비파괴 초음파탐상 자동화검사장비 개발)

  • Chai, Yong-Yoong
    • The Journal of the Korea institute of electronic communication sciences
    • /
    • v.15 no.1
    • /
    • pp.101-106
    • /
    • 2020
  • This research is related to a development of the ultrasonic detector for an internal defect detection of various assembly part's welding zone. In this research, measurement S/Ws including system's motion control, S/W ultrasonic transmitter/receiver control, defect judgment standard setting, etc. have been designed for ultrasonic detection, and welding defects sample network, etc. were also designed for comparison between products in good condition and defective products. Through this kind of system, automatic detection function can be performed for the depth and the defect location of the assembly parts welding zone, and the system is able to make a judgment of internal defect detection which is used to be performed by an expert in the past.

Determination of Incident Angle and Position of Optimal Mode Ultrasonic Beam for Flaw Detection in Anisotropic and Inhomogeneous Weldments by Ray Tracing

  • Zhao, Xinyu;Song, Sung-Jin;Kim, Hak-Joon;Gang, Tie;Kang, Suk-Chull;Choi, Yong-Hwan;Kim, Kyung-Cho;Kang, Sung-Sik
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.27 no.3
    • /
    • pp.231-238
    • /
    • 2007
  • Ultrasonic inspection of austenitic steel weldments is a truly difficult task due to complicated wave propagation phenomena such as beam skewing, splitting and distortion. In order to understand these phenomena and design proper inspection procedures, simulation is increasingly paid more attention to. This article addresses a ray tracing based approach to determine incident angle and position of optimal wave mode ultrasonic beam for flaw detection in anisotropic and inhomogeneous austenitic steel weldments. Specially, the optimal mode of ultrasonic wave wave is selected by ray tracing simulation, and an optimization approach based on ray tracing and bi-section search is proposed in order to find the ray path connecting two given points in weldments. With help of this approach, the optimal incident angle and position of ultrasonic beam can be determined for a given flaw position.

Application of Guided Ultrasonic Wave Technology for Evaluation of Welding Part in Cooling Water Pipe (냉각수 배관 용접부 평가를 위한 유도초음파 기술의 적용)

  • Gil, D.S.;Ahn, Y.S.;Park, S.K.
    • Journal of Power System Engineering
    • /
    • v.14 no.5
    • /
    • pp.36-40
    • /
    • 2010
  • The ultrasonic guided wave propagates along with the given structure's wall direction. Because of this specific character, the ultrasonic guided waves arc used in many other fields. Especially, it can be readily utilized for nondestructive inspection of various structures that are made up of gas pipes, heat exchanger tubes, and thin plates. Further, the guided wave technology can be readily utilized when inspecting pipes or thin plates which pose high risk of the accident but for which the nondestructive inspection itself is impossible because it is difficult to get to them since they are coated or buried underground. In the other hand, conventional ultrasonic testing such as thickness gauging uses bulk waves and only tests the region of structure immediately below the transducer. As a result of the application about inlet and outlet cooling water line using guided wave test, we conformed that the overall corrosions were in the lower side of the 304.8 mm inlet valve and these corrosions were engaged in not locally but through the lower side of the valve line. In the near future, we can expect that the detectable defect size is smaller than before along with the development of the sensing technology.

Detection of a Surface-Breaking Crack Using the Surface Wave of a Laser Ultrasound (레이저 초음파의 표면파를 이용한 표면결함 측정)

  • Park, Seung-Kyu;Jung, Hyun-Kyu;Baik, Sung-Hoon;Lim, Chang-Hwan;Joo, Young-Sang;Kang, Young-June
    • Journal of the Korean Society for Nondestructive Testing
    • /
    • v.26 no.2
    • /
    • pp.84-89
    • /
    • 2006
  • A laser ultrasonic inspection system is a non-contact inspection device which generates and measures ultrasounds by using laser beams. A laser ultrasonic inspection system provides a high measurement resolution because the ultrasonic signal generated by a pulse laser beam has a wide-band spectrum and the ultrasonic signal is measured from a small focused spot of a measuring laser beam. In this paper, we have investigated the detection techniques of a surface-breaking crack by using the laser ultrasonic surface waves. A crack acts as a low pass filter whose cut-off frequency is lowered in proportion to the depth of a crack. And, the center frequency value of a spectrum is decreased in proportion to the depth of a crack. In this paper, we extracted the crack information by using the frequency attenuation from the normalized transfer function spectrum of a surface-breaking crack. Also, we effectively measured the crack depth by using the decreasing value of the center frequency from a crack passed ultrasonic signal. The proposed measuring techniques of crack depths provided more precise information than the amplitude measuring technique.