On-line detection of power cable defects and faults

• Main Author: Teo, Wei Yi
• Other Authors: See Kye Yak
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Electric power::Production, transmission and distribution; DRNTU::Engineering::Electrical and electronic engineering::Antennas, wave guides, microwaves, radar, radio
• Online Access: http://hdl.handle.net/10356/71703
• Institution: Nanyang Technological University

A reliable electricity supply grid is critical for Singapore’s economic development. The industrial and commercial-related business are key stakeholders, and they both contribute to huge electricity demands annually. Disruptions to power will definitely affect the operations of these businesses, and result in significant losses for our economy. However, all these unnecessary power interruptions can be avoided by conducting frequent preventive maintenance on the cable systems. It is imperative to detect incipient faults on the cables before they can cause any potential disruptions. Well established fault detection tests that are being used in the industry include reflectometry and partial discharge tests. However, the system generally has to be shut down completely during these tests, resulting in the unavoidable disruption time. The present fault detection techniques are not able to accurately detect incipient cable faults, under system operating conditions as the cables remain energized. In this project, the novel on-line condition monitoring technique through inductive coupling was studied. The fault detection tests were conducted on a 230 volt cable system connected to an incandescent light bulb. The inductive coupling technique was found to be able to accurately measure the in-circuit impedance within the 300 kHz to 10 MHz frequency bandwidth. This technique was used to implement on-line condition monitoring tests for the light bulb system. Repeated measurements on the system resulted in similar impedance profiles, indicating that there were no faults present on the cable. Fault conditions such as a partial open circuit and damaged insulation were emulated on the cable systems, as an actual damaged cable was not available for this project. The fault detection tests were conducted on-line, and compared the impedance measured against a referenced impedance behaviour under the normal cable condition. The results for both conditions showed an increase in impedance at the higher frequencies, due to the inductive effect of the faults. Therefore, it is evident that the inductive coupling technique was successful in implementing on-line condition monitoring to detect incipient faults on the cable system. Introducing this technique to the industry will definitely improve the present preventive maintenance methodology.