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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 CHESF's 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.

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This paper describes the development of a single controller of DFB lasers for the simultaneous detection of multiple gases in the near infrared. A preliminary version of the system was implemented by use of a PIC18F4550 microcontroller, an oscillator, D/A converters, solid-state relays, DFB lasers and auxiliary circuitry. A preliminary performance analysis was carried out to determine the system capability in controlling two DFB lasers as well as to evaluate the system performance in detecting the absorption line of carbon monoxide at the wavelength 1568.036 nm.