San Diego Gas & Electric (SDG&E) provides natural gas and electricity to San Diego County and southern Orange County in southwestern California, United States. It is owned by Sempra Energy, a Fortune 500 energy services holding company based in San Diego. The company is known for having the highest rates in the country. SDG&E is a regulated public utility that provides energy service to 3.3 million consumers through 1.4 million electric meters and more than 840,000 natural gas meters in San Diego and southern Orange counties. The utility's area spans 4,100 square miles (10,600 square kilometers). SDG&E employs about 5,000 people.
Successfully detecting high-impedance faults due to downed or broken power distribution conductors in a timely manner has been a big challenge for decades. When an energized broken conductor makes contact with the ground, it may result in a high-impedance fault that may be a challenge to detect using traditional protection methods. This paper provides a review of the existing solutions to detect downed conductors that have made contact with the ground. It is important to highlight that these solutions detect and isolate the affected circuit section only after the energized conductor has been on the ground for several seconds or minutes. This creates a critical “race-against-time” scenario, posing wildfire risks and public safety hazards. This paper dives deeper into an innovative method that was developed and successfully implemented on 12 kV distribution circuits to detect and isolate broken conductors while they are in the air and before they touch the ground. The IEC 61850 Generic Object-Oriented Substation Event and IEEE Std. C37.118 synchrophasor-based falling conductor protection solution is designed to detect and isolate broken conductors well within 500 ms of the break. This protection-speed solution is applicable to three-phase circuits along with two-phase and single-phase laterals that may be in high fire risk areas. This paper further explores the implementation of the falling conductor protection solution using Ethernet radios, and direct fiber, as well as private long-term evolution communication networks, which form the backbone of the falling conductor protection solution.
Overhead (OH) medium-voltage air-break electric distribution switches with bare copper contacts located within a six-mile proximity of the Pacific Ocean coast in San Diego Gas & Electric's (SDG&E) service territory have been observed with corrosion and have a higher replacement rate than similarly aged OH inland switches which do not exhibit the same corrosion growth. These OH failures are associated with extended outages, increased System Average Interruption Duration Index (SAIDI), and increased System Average Interruption Frequency Index (SAIFI). This research has been investigating copper corrosion properties leading to the formation of high-impedance oxides that may be associated with OH bare copper contact switch failure along the coast. Using scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS) the copper oxide thickness, impedance, and composition were quantified. Cuprite and atacamite were identified as the two primary copper oxides formed at the surface of the switches. Atacamite was the thickest oxide layer identified. Cuprite and atacamite were found to have significantly higher impedance than bare copper. The oxides' impedance could restrict current flow, leading to increased contact heating. As a conclusion, bare copper contact switches should not be installed in areas near the coast.
OBJECTIVE:This study evaluates the feasibility of a noninvasive system for monitoring diaphragmatic efficiency in people with cervical spinal cord injury (CSCI). METHODS:Two versions of a portable hardware system were developed using impedance pneumography (IP) to measure tidal volume (TV) and surface electromyography (sEMG) to assess diaphragm electrical activity (EAdi). Version 1 was used to determine optimal electrode positions, while Version 2 integrated these sensor systems into a compact, portable design. Data from eight healthy male participants were analyzed to assess the correlation and accuracy of TV and respiration rate (RR) prediction using IP and the correlation between sEMG signals and maximum inspiratory pressure (MIP). RESULTS:For IP, measurements between the upper sternum and the midclavicular line (MCL) at the 4th intercostal (IC) space showed the highest correlation with true tidal volume. For sEMG, measurements between the mid-sternum and the 6th IC space demonstrated the strongest correlation with MIP. The integrated version 2 hardware demonstrates simultaneous IP and sEMG measurement while dissipating 2.17 mW. DISCUSSION/CONCLUSION:The proposed system and the results presented may lead to a practical, cost-effective solution for continuous diaphragmatic efficiency monitoring, and thus enabling home-based respiratory care of CSCI patients. Clinical and Translational Impact Statement- This work presents the feasibility of building a wearable system that can unobtrusively monitor diaphragmatic efficiency, and thus enabling noninvasive, cost-effective, and home-based respiratory care for CSCI patients, facilitating early intervention and improved long-term health outcomes. This study is categorized under the early/pre-clinical research category of the NIH Clinical spectrum.
Successfully detecting high-impedance faults due to downed or broken power distribution conductors in a timely manner has been a big challenge for decades. When an energized broken conductor makes contact with the ground, it may result in a high-impedance fault that may be a challenge to detect using traditional protection methods. This paper provides a review of the existing solutions to detect downed conductors that have made contact with the ground. It is important to highlight that these solutions detect and isolate the affected circuit section only after the energized conductor has been on the ground for several seconds or minutes. This creates a critical "race-against-time" scenario, posing wildfire risks and public safety hazards.This paper dives deeper into an innovative method that was developed and successfully implemented on 12 kV distribution circuits to detect and isolate broken conductors while they are in the air and before they touch the ground. The IEC 61850 Generic Object-Oriented Substation Event and IEEE Std. C37.118 synchrophasor-based falling conductor protection solution is designed to detect and isolate broken conductors well within 500 ms of the break. This protection-speed solution is applicable to three-phase circuits along with two-phase and single-phase laterals that may be in high fire risk areas. This paper further explores the implementation of the falling conductor protection solution using Ethernet radios, and direct fiber, as well as private long-term evolution communication networks, which form the backbone of the falling conductor protection solution.
