Cable Fault Detection: Optical Fiber Current Sensor Cable Link Noise Reduction

Abstract

In fiber optic current sensors, two main parts, the sensor head unit and the drive/control/chassis unit, are connected by optical fiber cable links. The fiber link carries measurement information from the sensor to an electronics chassis faraway. The optical cable can be wrapped around the main high voltage/current conductors to reduce cost. However, a fiber wrapped around the conductor will have an induced Faraday effect due to the power conductor magnetic field. This creates an unwanted current signal pickup. Also, vibrational pickup due to the macro and micro bend loss of this fiber cable is present as well. These unwanted signals interfere with electric current measurement in a very problematic and erratic way. We have demonstrated by employing optical depolarizers in the sensor fiber link a method of reducing unwanted vibrational and current pickup in the sensor.