Lima R

Novel sensor system for leakage current detection on insulator strings of overhead transmission lines

We report the development of a measurement system capable of monitoring and characterizing the main features of the leakage current flowing on a polluted insulator string of a high-voltage transmission line. The system comprises a fiber-optic sensor, directly connected to one insulator of the string, that emits a sample of the leakage current waveform to a processing module via an optical link. A capacitive sensor connected to the processing module allows recording the relative humidity of the outer environment. At the present stage, six measurement units have been deployed on CHESFs electrical transmission system in the Northeast of Brazil, and studies are underway to further correlate the degree of environmental pollution with humidity and leakage current activities on high-voltage insulator strings

Sensor Network for Monitoring the State of Pollution of High-Voltage Insulators Via Satellite

This paper describes the design and development of a sensor system network for remote monitoring of the state of pollution on high-voltage insulators, its deployment among four states in Northeast Brazil and preliminary analysis of the data gathered by the system. Six monitoring units, each composed by leakage current, humidity, and temperature sensors, an electronic processing module, and a satellite-communication link, were built and installed on 230- and 500-kV transmission towers. Measured data are sent by the different systems via satellite to a database controlled by a web-based graphical user interface, incorporated into the supervision-management system of the electric utility company. Sample field results on one of the sensor systems, both for short- and long-term measurements, show a direct correlation of the activity recorded by the system with the pollution level expected to occur near the corresponding monitoring point.

Fiber-optic sensor system for leakage current detection on insulator strings of overhead transmission lines

In this paper we report the development of an optical system capable of monitoring and characterizing the main features of the leakage current flowing on a polluted insulator string of a high-voltage transmission line. The system comprises a fiber-optic sensor, directly connected to one insulator of the string, that emits a sample of the leakage current waveform to a processing module via an optical link. At the present stage, six different systems have been deployed on CHESFs electrical distribution system in the Northeast of Brazil, and studies are underway to further correlate the degree of environmental pollution with humidity and leakage current activities on high-voltage insulator strings.

Satellite telemetry system for pollution detection on insulator strings of high-voltage transmission lines

Leakage current monitoring is a promising method of indirect estimation of pollution levels on insulators strings of high voltage transmission lines. This paper describes the development of a complete real time leakage current monitoring sensor system. This system is composed of an optical sensor with a fiber link, a processing microcontrolled module, a satellite link and a solar panel with battery. The most important characteristics obtained from the leakage current signal are internally stored in the PIC16F877A microcontroller and transmitted through the satellite communication link. The information is downloaded from the website of the satellite link provider and inserted in a database with a web-based graphical user interface.

Remote monitoring of the degree of pollution of high voltage insulator strings via satellite with a sensor system network

A sensor system network was developed and installed in the northeast of Brazil to monitor the degree of pollution of insulator strings of high voltage transmission lines. Monitoring systems, comprising leakage, humidity and temperature sensors, a processing electronic module and a satellite communication link were installed on 230 and 500 kV towers. Measured parameters, sent via satellite to the communication service provider are downloaded to a local server managed by a web-based GUI application. The degree of pollution in the insulator string can be inferred from the time rate of discharge pulses appearing in the leakage current signal and its correlation with local humidity and/or temperature. Preliminary real time field results measured in the network are analyzed.

Experimental observation of surface plasmon resonance in a gold-coated multimode fiber

We observed for the first time evidence of the surface plasmon resonance(SPR) effect within the light distribution irradiated from a gold-coated multimode fiber immersed in a wet environment. Experimental measurements conducted with NaCl sample solutions allowed demonstrating the application of the technique in optical sensing whereby modifications in the shape of the irradiated intensity pattern are linearly correlated with changes in solute concentration. Measurement results indicate that this detection technique provides at least a 10-fold sensitivity enhancement relative to that achieved by a previously reported SPR-based fiber sensor.