An
all fiber optic
electric field sensor for indoor
switchgear phase conductor
bus bar
voltage sensing, which is galvanically isolated from the electric circuit of the
switchgear power
distribution system, featuring a single mode
optical transmitter, installed on the front side of a
switchgear cubicle, which connects via an optical patch cord routed in conduit to a passive, in-line,
all fiber polarization filtering module installed on the back of the switchgear cubicle, which connects to an all
dielectric single mode
fiber optic
voltage sensor cable with standardized Kerr constant, routed within insulating all
dielectric rigid conduit, which is secured with mechanical support brackets, featuring integrated vibration dampers, which traverses an
optical path in parallel with a phase conductor
bus bar and a ground
bus, and where the degree of
electric field induced
birefringence occurring on the
optical path which is perpendicular to the
electric field radiating from the phase conductor is measured by observing the phase shift occurring in the orthogonally polarized
modes during traversal of the single mode electro-optical
voltage sensor cable perpendicular to the electric field, where an output of the sensor cable is analyzed with a 1×2 polarization maintaining
fiber coupler which divides the polarized optical
signal power equally to measure the preponderance of right circular polarized light over left circular polarized light, with the difference in
optical intensity observed at the photodiodes proportional to the phase shift which varies exponentially with the electric field potential as an inverse function of
linear distance from the phase conductor.