Development of a Differential Microwave System to Measure Traces of Water in SF6
- 1 January 2006
- conference paper
- Published by Institute of Electrical and Electronics Engineers (IEEE)
Abstract
We report on the construction and evaluation of a prototype of a humidity meter based on a microwave differential circuit. This circuit has been developed to perform on-line monitoring of the humidity present in high power electrical equipment insulated with SF 6 . The set up is built around two cylindrical tuneable microwave cavity resonators operating in the TE011 mode. One is filled with a pure sample of SF 6 and the other one with the contaminated sample under test, both are connected to a 180deg hybrid junction and are fed with a modulated carrier. Following demodulation done with lock-in detection implemented in software, we obtain a signal proportional to the concentration of contaminant in the gas. We have made measurements of the output signal for different samples of SF 6 contaminated with water having concentrations ranging from 20 to 400 ppm; we have determined that our circuit has a water vapour detection threshold of about 5 ppm at atmospheric pressure and room temperatureKeywords
This publication has 4 references indexed in Scilit:
- Optimization study of a microwave differential technique for humidity measurement in gasesIEEE Transactions on Instrumentation and Measurement, 2001
- Performance of a microwave sensor for the precise measurement of water vapor in gasesIEEE Transactions on Dielectrics and Electrical Insulation, 2000
- Investigation of a microwave differential cavity resonator device for the measurement of humidity in gasesReview of Scientific Instruments, 1999
- Dielectric and pressure virial coefficients of imperfect gases: Hexadecapolar systemThe Journal of Chemical Physics, 1974