- Switch gear at AREVA SUZHOU in China
Monitoring Sulphur Hexafluoride in the Power Utility Industry
During the past few decades, there has been a change in the insulating medium used in high-voltage switchgears as manufacturers have replaced oil units with SF6-insulated units. Today the power utility industry uses roughly 80% of all SF6 produced worldwide and it is mainly used in gas insulated switchgear (GIS) and circuit breakers, but also in e.g. cables, tubular transmission lines and transformers. Unfortunately SF6 is one of the most potent greenhouse gases with a Global Warming Potential of 24,000 times greater than of CO2. Protecting the environment is a very big issue today, but there has not yet been found any adequate substitutes for SF6 in these applications.
Besides being hazardous to the environment, the processes of arcing, sparking discharging etc., causes SF6 to produce toxic by-products. The most dominant by-product; thionyl fluoride (SOF2) can decompose to SO2 an HF, which can be particularly damaging to the health and safety of the workforce.
In 1997 the Kyoto Protocol was accepted. It deals with limitation of emission of greenhouse gases including SF6. Since it is not possible to replace SF6 in the power utility with another, less harmful gas a number of working routines have been introduced with the purpose of minimizing emissions of SF6.
Conclusion
- Photoacoustic Multi-gas Monitor - INNOVA 1314
Manufacturers found that the time required for their approval tests could be reduced considerably, thereby boosting productivity by as much as a factor of four.
In order to monitor a "farm" of switch-gears, the monitor is connected to a multiplexer. Samples are drawn from up to twelve different points via tubes, which are connected to the inlet of the multiplexer. The outlet from the multiplexer is fed to the monitor, which is calibrated to a detection limit low enough (e.g. 5 ppb) to meet the customers' specification.
The system is able to monitor unattended for extended periods of time. The monitor's extended self-test routines maintain the reliability of the results, which are available on-line or can be dumped when required.