A compensation method for an optical direct current sensor using ripple

This paper introduces an optical sensor, considering attenuation variance of input and output fibres using technical ripple current to determine the magnitude of direct current. Changing attenuation varies the characteristic curve of the sensor transfer function. Therefore changed attenuation has to be detected and its effect needs to be compensated. It needs to be differentiated, if input or output fibre attenuation changes. For reasons of low costs and easy installation a magnetic field sensor is used to calculate current in a nearby conductor. The influence of external magnetic fields is prevented by design of the test set-up and can be neglected.