Magnetic cross-talk compensation for an Optical Current Transducer

In this paper we analyse the errors associated with magnetic cross-talk within point type, or unlinked, Optical Current Transducers (OCTs) working in the three-phase electric current transmission systems. It is shown that, for most practical conductor arrangements, the magnetic cross-talk is sufficient to introduce errors unacceptable for the accuracy requirements demanded front the OCT. A solution to this problem is devised around a unique compensation method which solves, in real time, a set of linear equations, each representing the instantaneous output signal from one phase current sensor. The equations are created using calibration factors which can be evaluated for the particular conductors arrangement using experimental or analytical methods. The solution of the above set of equations may be implemented using Digital Signal Processing (DSP), which provides the number of sought instantaneous values of currents in the considered conductors arrangement.