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An impulse voltage calibrator of low output impedance
IEEE Transactions on Power Delivery, 2005A calibrator that produces full lightning impulses and chopped lightning impulses with variable chopping time is described. The calibrator uses series-connected power metal-oxide field-effect transistors as the main impulse switch and insulated gate bipolar transistors (IGBTs) as the chopping switch, and its output impedance is low to drive a ...
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A reduced-scale experimental study of tower impulse grounding impedance
2017 1st International Conference on Electrical Materials and Power Equipment (ICEMPE), 2017Lightning withstand level of the transmission line is directly affected by the value of the tower impulse grounding impedance. While it's difficult to obtain the tower impulse grounding impedance accurately as its nonlinearity under impulse current. Therefore the study of the tower impulse grounding impedance characteristics is significant to lightning
Jiangtao Li +5 more
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Impulse impedance tests on laboratory model ground electrodes
IEE Proceedings - Generation, Transmission and Distribution, 2003Impulse impedance of vertical rods embedded in several soil types was determined by laboratory tests under four temperatures and four soil moisture contents with three different waveshapes of the applied impulse voltage. To avoid errors due to current spikes caused by soil ionisation, it is proposed that the impulse impedance be defined as the ratio ...
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Reconstruction of Acoustic Impedance Profile from Its Reflection Impulse Response
1981 Ultrasonics Symposium, 1981If the r eflection impulse response of a nonattenuating medium with a one-dimensional continuous impedance profile is given, the acoustic impedance as a function of travel time can be reconstructed. One reconstruction technique, utilizing the impediography equation, c onsiders o nly the first order reflections while the other technique which takes into
P. He, P.C. Pedersen, O.J. Tretiak
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Investigation on transformer oil impedance during breakdown under impulse voltage
2014 IEEE Electrical Insulation Conference (EIC), 2014This paper presents an experimental investigation on transformer oil subject to impulse voltage. The dynamic impedance of the mineral oil samples was determined from the instantaneous ratio of voltage and current characteristics at the instant of breakdown. A dedicated test cell was constructed to contain the insulating oil.
S. Abdi +3 more
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An impulse method of measuring normal impedance at oblique incidence
Journal of Sound and Vibration, 1979Abstract An experimental method of determining the oblique incidence behaviour of sound absorbing materials is given. The method involves the measurement of acoustic impulses at the surface of an absorbing material and comparing the complex frequency components with those of a reference signal recorded remote from the surface.
J.C. Davies, K.A. Mulholland
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Reflection of impulses as a method of determining acoustic impedance
The Journal of the Acoustical Society of America, 1984An impulse technique has been developed which allows investigation of the reflection of acoustic transients at different angles from an impedance boundary. From measurements of the direct and reflected impulses, the complex surface impedance has been calculated from the ratio of the corresponding Fourier components.
A. J. Cramond, C. G. Don
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A new impulse grounding impedance detection device for transmission tower
2016 International Conference on Condition Monitoring and Diagnosis (CMD), 2016To obtain impulse impedance characteristics for grounding device of transmission tower, a small and portable instrument is developed. It can stable output the 8/20 µs and 10/350 µs standard lightning currents with simultaneous measurement of the response transient voltage waveshapes, which simulates the currents of direct and indirect lightning strikes,
Yue-Qiang Wang +4 more
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The impulse grounding impedance computation in HVDC transmission line tower
2013 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC), 2013Electromagnetic field and circuit theory combined is applied to calculate the impulse grounding impedance in HVDC transmission line towers in this paper. The mutual inductance of conductor segments are taken into account. At the same time, the images of the self resistance and mutual inductance are considered for the different medium (soil and air ...
Li Tian-wei, Xiang Yang, Zhao Yu-ming
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Research on impulse impedance measurement for grounding device of transmission tower
2016 IEEE International Conference on High Voltage Engineering and Application (ICHVE), 2016For obtaining impulse impedance characteristics for grounding device of UHV 1000 kV transmission tower, a portable instrument is used as the incident wave source to the grounding device, which stably outputs a 8/20 μs standard lightning current with simultaneous measurement of the response transient voltage.
Si Wen-Rong +4 more
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