TY - GEN
T1 - Improvement in sensitivity of broadband impedance spectroscopy for locating degradation in cable insulation by ascending the measurement frequency
AU - Yamada, Takayuki
AU - Hirai, Naoshi
AU - Ohki, Yoshimichi
PY - 2012/12/1
Y1 - 2012/12/1
N2 - In order to develop a truly reliable method for locating a degraded portion in a cable, we are developing a method based on the frequency domain reflectometry and inverse fast Fourier transform (IFFT). The locating ability of this method was examined for three types of degradation given to three kinds of cables, each with a length ranging from 24.4 to 29.0 m. Namely, a vented water tree was simulated in a coaxial cable insulated with cross-linked polyethylene (XLPE) by making a tiny hole filled with a NaCl solution, and γ-ray-induced aging was given for a length of 80 cm of an XLPE-insulated triplex cable, while the mutual distance between the two conductors was expanded for 10cm in a cord insulated with polyvinyl chloride. Analyses by IFFT using the data obtained from 1 MHz to 100 or 110 MHz can locate all three types of degradation, but the resolution is poor. If the highest measurement frequency is ascended to 200 to 400 MHz, the resolution becomes better. Moreover, the spectrum indicating the degraded portion shows quite a good reproducibility unless the cable is moved. This means that this method can be a very sensitive degradation locating tool usable for real cable systems.
AB - In order to develop a truly reliable method for locating a degraded portion in a cable, we are developing a method based on the frequency domain reflectometry and inverse fast Fourier transform (IFFT). The locating ability of this method was examined for three types of degradation given to three kinds of cables, each with a length ranging from 24.4 to 29.0 m. Namely, a vented water tree was simulated in a coaxial cable insulated with cross-linked polyethylene (XLPE) by making a tiny hole filled with a NaCl solution, and γ-ray-induced aging was given for a length of 80 cm of an XLPE-insulated triplex cable, while the mutual distance between the two conductors was expanded for 10cm in a cord insulated with polyvinyl chloride. Analyses by IFFT using the data obtained from 1 MHz to 100 or 110 MHz can locate all three types of degradation, but the resolution is poor. If the highest measurement frequency is ascended to 200 to 400 MHz, the resolution becomes better. Moreover, the spectrum indicating the degraded portion shows quite a good reproducibility unless the cable is moved. This means that this method can be a very sensitive degradation locating tool usable for real cable systems.
KW - broadband impedance spectroscopy
KW - cable
KW - condition monitoring
KW - frequency domain reflectometry
KW - insulation diagnosis
KW - location of cable degradation
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U2 - 10.1109/CMD.2012.6416236
DO - 10.1109/CMD.2012.6416236
M3 - Conference contribution
AN - SCOPUS:84874240077
SN - 9781467310208
T3 - Proceedings of 2012 IEEE International Conference on Condition Monitoring and Diagnosis, CMD 2012
SP - 677
EP - 680
BT - Proceedings of 2012 IEEE International Conference on Condition Monitoring and Diagnosis, CMD 2012
T2 - 2012 IEEE International Conference on Condition Monitoring and Diagnosis, CMD 2012
Y2 - 23 September 2012 through 27 September 2012
ER -