Siemens Set GGA (Generator Gas Analyzer) is a standardized set to control hydrogen-cooled turbo generators. Turbo generators in power plants are cooled with gas in order to increase their efficiency. This offers huge advantages like better cooling properties, lower friction loss on rotating parts, and a higher electrical breakdown strength.

Hydrogen gas is potentially explosive in mixtures with air over a wide concentration range (4 to 77%). Formation of such mixtures must be prevented for safety reasons during normal operation as well as during maintenance work. International Standards (EN and IEC) specify the installation of a redundant safety control system with two independent measuring systems.

In addition, contamination of the hydrogen cooling gas reduces the efficiency of the turbo generator, as it leads to considerably higher friction loss. For a 970 MW generator, a difference of 4% is equivalent to a 0.8 MW difference in power. There are also good reasons related to cost-effectiveness why the cooling gas should be continuously monitored for contamination.

The Set GGA is a complete solution for monitoring hydrogen-cooled turbo generators, with the dual benefit of being simple to handle and having low initial investment costs.