---

Various Information Obtained from Acoustic Emissions Owing to Discharges in XLPE Cable

Year: 2012 Volume: 6 Issue: 9 1068 - 1073 Pages

• Authors:
• Tatsuya Sakoda
• Yuta Nakamura
• Junichiro Kitajima
• Masaki Sugiura
• Satoshi Kurihara
• Kenji Baba
• Koichiro Kaneko
• Takayoshi Yarimitsu

Abstract: An acoustic emission (AE) technique is useful for detection of partial discharges (PDs) at a joint and a terminal section of a cross-linked polyethylene (XLPE) cable. For AE technique, it is not difficult to detect a PD using AE sensors. However, it is difficult to grasp whether the detected AE signal is owing to a single discharge or not. Additionally, when an AE technique is applied at a terminal section of a XLPE cable in salt pollution district, for example, there is possibility of detection of AE signals owing to creeping discharges on the surface of electric power apparatus. In this study, we evaluated AE signals in order to grasp what kind of information we can get from detected AE signals. The results showed that envelop detection of AE signal and a period which some AE signals were continuously detected were good indexes for estimating state-of-discharge.

• Keywords:
• acoustic emission
• creeping discharge
• partial discharge
• XLPE cable

Multiple-Points Fault Signature's Dynamics Modeling for Bearing Defect Frequencies

Year: 2011 Volume: 5 Issue: 11 2515 - 2520 Pages

• Authors:
• Muhammad F. Yaqub
• Iqbal Gondal
• Joarder Kamruzzaman

Abstract: Occurrence of a multiple-points fault in machine operations could result in exhibiting complex fault signatures, which could result in lowering fault diagnosis accuracy. In this study, a multiple-points defect model (MPDM) is proposed which can simulate fault signature-s dynamics for n-points bearing faults. Furthermore, this study identifies that in case of multiple-points fault in the rotary machine, the location of the dominant component of defect frequency shifts depending upon the relative location of the fault points which could mislead the fault diagnostic model to inaccurate detections. Analytical and experimental results are presented to characterize and validate the variation in the dominant component of defect frequency. Based on envelop detection analysis, a modification is recommended in the existing fault diagnostic models to consider the multiples of defect frequency rather than only considering the frequency spectrum at the defect frequency in order to incorporate the impact of multiple points fault.

• Keywords:
• Envelop detection
• machine defect frequency
• multiple faults
• machine health monitoring.