Development of an electric field sensor for electrical-proximity and contact detection.
Zeng-S; Powers-JR; Newbraugh-BH
NOIRS 2008-Abstracts of the National Occupational Injury Research Symposium, October 21-23, 2008, Pittsburgh, Pennsylvania. Morgantown, WV: National Institute for Occupational Safety and Health, 2008 Oct; :G1.4
Introduction: The 998 electrocution deaths in 2003-2006 accounted for 5.8% of total U.S. occupational fatalities. Most victims (73.9%) had fatally contacted overhead power lines, wiring, or other electrical components. To protect workers from touching live wires, NIOSH developed a digital electrical proximity/contact sensor that workers wear for the purpose of alarming the worker and others as it detects the worker's proximity/contact to live wires. Methods: The sensor senses 60-Hz electric fields emitted from live wires to a worker's wrist. The field level on the wrist increases as the worker goes closer to the wire. The sensor includes a pair of capacitive electrodes attached on one wrist that detects electric fields, a 60-Hz filter that rejects interference signals, and two amplifiers (with an adjustable gain) that amplify electric field signals. To determine whether the field variations on simulated human wrists are detectable by the above electrode/electronic setup, an experiment was conducted using the sensor to sense electric fields on 10 hog legs at low/high voltages. Results: At 120 volts, the sensor with the gain of 64,931 sensed 1.3 microvolts on a hog leg as the leg was 100 centimeters away from an energized simulated power line, and 17.5 microvolts as the leg was moved to 1 centimeter to the wire. As the leg contacted the bare wire, the sensor measured 473.7 microvolts with the reduced gain of 3,135. At 9,000 volts, with the gain adjusted to 571, the sensor sensed 90.9 to 2,456.4 microvolts as the leg was moved the same distance as above. Conclusions: The electrode/electronic setup has enough sensitivity and dynamic range to detect hog legs' electrical proximity and contact to an energized power line.
Accident-prevention; Accidents; Construction-equipment; Construction-workers; Control-technology; Electrical-fields; Electrical-hazards; Electrical-industry; Electrical-measurement-devices; Electric-power-transmission-lines; Electrocutions; Exposure-assessment; Exposure-methods; Injuries; Injury-prevention; Laboratory-testing; Occupational-accidents; Occupational-exposure; Occupational-hazards; Personal-protective-equipment; Protective-equipment; Statistical-analysis
NOIRS 2008-Abstracts of the National Occupational Injury Research Symposium, October 21-23, 2008, Pittsburgh, Pennsylvania