Conference,
POWER FREQUENCY ELECTRIC-FIELD MITIGATION TECHNIQUES
(2013)
Abstract
In overhead air-insulated high-voltage (HV) systems, elevated electric fields exist in space around
equipment and conductors where there are human activities associated with working in substations or
traversing/using of land on the transmission line ROW/easements. Via capacitive coupling, small
electric charge-transfers through the air from the HV system to nearby conductive objects including a
human body occur, and accordingly an electric potential/voltage exists on each object. In the case that
a person further makes contact with another object, new charge transfer/electric current occurs, in
particular the transient phase (breakdown of air just before contact, a spark discharge) manifests as
sensory effects at the point of contact such as finger/hand or part of the body. The levels of effect,
ranging from barely perceptible to painful reactions depend on amount and pattern of the charge
transfer. Mitigating these sensory effects, including a potential secondary reaction/fall, can principally
done by firstly dealing with the source of electric-field, secondly shielding or reducing the electric
field at locations of interest, and thirdly by preventing/providing alternate paths for charge transfer or
reduction of capacitive coupling. The latter approach includes mitigation through grounding/earthing,
bonding, using protective clothing & footwear, applying working practices, training and information
program. These mitigation methods will be discussed along with a number of case studies in this paper.
