Abstract:
High voltage A.C. transmission is the common mode adopted in transmitting bulk electrical
power from one station to the other all over the world. Associated with these overhead
transmission lines are the electric and magnetic fields emanating from these which could have a
coupling influence on devices in its proximity. Detonator is one such electro explosive device
(EED) that is susceptible to electromagnetic coupling when placed in proximity to the
transmission lines which in turn could cause inadvertent misfires.
This report focuses on the computational modeling of electric and magnetic fields around
overhead high voltage transmission lines at various voltage levels and line configurations starting
from fundamental electromagnetic principles and the verification of those models by field
measurements. MATLAB software was used in modeling the field profiles and the model is
capable of accommodating any configuration with any number combination of conductors. The
overhead transmission line parameters used in this report are from the present line configurations
in practice in Sri Lanka. The measured values of electric and magnetic fields are compared with
the modeled values for the verification of models. The possibility of shielding these extra low
frequency electromagnetic fields are also discussed briefly.
Electrical detonator is one type of Electro Explosive Devices (EEDs) that is used to initiate blast
sequences. the susceptibility of these devices to the electric and magnetic fields emanating from
nearby high voltage transmission lines are comprehensively examined under scenarios of
nominal rated loads, infrequent high loads, emergency short-time loads, faults, lightning and
switching surges. Investigating the impacts of field couplings and possible unintentional misfires
under different scenarios, safe distance levels for operation of detonators in the proximity of
transmission lines are proposed for different voltages and line configurations.
