Study of HF Gas Detection in Electrical Equipment by TDLAS Technology

The schematic diagram of the optical cavity design has been introduced in detail, meanwhile, the principle of measuring gas concentration with optical resonator is also introduced. Using the optical cavity spectroscopy technology, the gas component detection system is set up to realize high precision on-line monitoring of gas components such as HF. The detection system uses narrow line-width semiconductor laser to select the characteristic gas spectrum and output the absorption peak wavelength. Three kinds of gas concentration are measured by time division multiplexing, and the on-line sampling device of closed loop gas is integrated to complete the monitoring platform of high precision. The system needs the saw-tooth wave of 1Hz, which can be generated by internal DA of ADSP-403. At the same time, the system needs a modulation signal of about 5kHz, and the debugging signal with such high frequency can not be generated by DA of micro-controller itself. The system uses DDS generator AD9850 to generate sinusoidal modulation signal which is superimposed on the saw-tooth wave to drive the laser. The paper has developed the SF6 composition monitoring device based on optical attenuation technology, which provides the new research method for the on-line monitoring of gas components such as HF with the high accuracy of 3ppm.