In this paper, we describe a low cost optical sensor of water level based on fiber bending effect associated to the use of an elastomeric membrane. The sensor proposed has a particular design to be simple, reliable, and low cost. It is suitable to be used in tubes of embankment dams, tanks, and reservoirs. The sensor uses a standard single mode fiber and can measure the water levels up to 10 m or more, choosing the appropriate membrane. This paper describes the development of the sensor, a theoretical modeling, and the results of laboratory and field tests. Seven sensors were installed in an embankment dam where they have been used in a real time monitoring system based in optical time domain reflectometry.

Double-pass (DP) and single-pass (SP) erbium-doped depressed cladding fiber amplifiers designed for S-band operation are evaluated under changes of the input optical power, pumping power, and fiber bending radius. The DP configuration employs the usual combination of a circulator and a Faraday rotator mirror while the SP is based on the copropagating scheme. The amplifiers were characterized in terms of gain and noise figure. It is demonstrated that the DP topology shows much improved gain performance compared to the SP configuration although the noise figure is slightly degraded by counterpropagating amplified spontaneous emission.

Power‐Over‐Fiber Applications for Telecommunications and for Electric Utilities | InTechOpen, Published on: 2017-06-21. Authors: Joao Batista Rosolem

This paper described a distributed temperature sensing (DTS) system based on Raman scattering using pre-shaped simplex code (S code) with erbium-doped fiber amplifiers (EDFAs) transient effects suppression techniques. We investigated these techniques to mitigate the waveform distortion caused by the EDFA when DTS uses S code in an optical time-domain reflectometer (OTDR). We tested the DTS experimentally using two EDFA's transient effects suppression techniques: automatic gain control and pre-shaped S code pulses. The performance of these two techniques working simultaneously was compared with the standard S code technique. In the experimental setup, we tested code word lengths from 3 to 127 b with 100-ns pulsewidth. The temperature measurement demonstration was done in reaches of 40 and 50 km, and in a repeated system of 62 km using standard single-mode fiber and commercial OTDR and EDFA modules, which were properly adapted to this application. Results show that EDFA's transient effects suppression techniques allow increasing the reach of DTS using short S code sequences, reducing the complexity and the processing time.

In this work, we present the design, laboratory tests, and the field trial results of a power-over-fiber (PoF) low power instrument transformer (LPIT) for voltage and current measurements in the medium voltage distribution networks. The new proposed design of this power-over-fiber LPIT aims to overcome the drawbacks presented by the previous technologies, such as the continuous operation (measuring and data transmission) for a wide current range conducted in the medium voltage transmission lines, damage due to lightning strikes, accuracy dependency on vibration, position and temperatures. The LPIT attends the accuracy criteria of IEC 61869-10 and IEC 61869-11 in terms of current and voltage accuracy and it attends the practical criteria adopted by Utilities companies including voltage measurements without removing the coating of the covered conductors. The PoF based LPIT was developed to be applied at 11.9 kV, 13.8 kV, and 23.0 kV phase-to-phase nominal voltages, and in two current ranges 1.25–30 A and 37.5–900 A. The digital data transmission of current, voltage, and temperature from the sensing unit to the processing unit uses a special synchronism technique and it is performed by two 62.5 µm multimode fibers in 850 nm. The optical powering in 976 nm is also performed by one 62.5 µm multimode fiber from the processing unit to the sensor unit. We presented all details of the sensor design and its laboratory characterization in terms of accuracy and temperature correction. We also presented the results of field tests of the sensor made in two different conditions: in a standard distribution network and an experimental hybrid fiber/power distribution network. We believe that these studies aim to incorporate optical fiber and devices, digital technologies, communications systems in electrical systems driving their evolution.

In this work we proposed a sealing method of fiber Bragg grating (FBG) in pressure sensors using electroless nickel-plating. The sensor is designed to be used in harsh environments of thermoelectric power plant engines. In order to be applied in the engine injector nozzle the FBG has just a single attached point in the pressure sensor and the combustion chamber pressure will freely compress the FBG. The fixation material used to seal the FBG in the pressure sensor is the key for the sensor performance considering the engine environment used in thermoelectric power plant. Typical level of pressure in the engine monitoring point is around 200 bar and the temperature exceed 300 °C. We detailed the method of fabrication and the characteristics of this method. Next the FBG pressure sensors using electroless nickel-plating sealing were studied and submitted to laboratorial and field trial evaluation. In addition, we evaluated the signal characteristics of the FBG pressure sensor and we compared it with a standard pressure sensor used in this application.