Detachable triangular-shaped bulk-optic glass sensor for simultaneous three-phase current measurement

In this paper, we describe a detachable triangular-shaped bulk-optic glass sensor for three-phase current measurement using only one laser source. The sensor is constructed from three separate SF6 glass rods that form a triangle, where the coils of the three-phase current are mounted separately on the glass rods. Laser light is guided through the glass in a closed loop by reflecting twice at the critical angle at the two corners of the triangle. On the reflection surface of each corner, light is tapped with a right-angle prism that is pressed against the surface. The light beams tapped from the two corners and that emerging from the exit face of the sensor carry different components of the three-phase current. By processing these three light signals, the three phases of the current can be determined. To demonstrate the principle, an experimental sensor has been constructed and tested.