WIKA GDT-20 and GDHT-20 SF₆ sensors

The GDT-20 and GDHT-20 transmitters from WIKA provide the foundation for continuous, digital monitoring of the quenching and insulating gas sulphur hexafluoride (SF₆). They are designed to be used to give a clear indication of the SF₆ condition of gas-insulated equipment and thus enable maintenance to be planned solely on demand.

Based on precise pressure and temperature measurement, the two transmitters constantly calculate the density of SF₆ so that leaks are identified at an early stage. The model GDHT-20 also measures the gas humidity, so that the formation of corrosive decomposition products can be prevented. If the equipment is filled with SF6 gas mixtures, such as SF₆/N₂ or SF₆/CF₄, both instruments can be configured by the user.

The continuous monitoring of SF₆ from the control room gives the foundation for condition-based, and thus cost-optimised, equipment maintenance. The digitised measuring process brings a further advantage: by using the standard Modbus RTU protocol, the data of up to 247 instruments can be retrieved from  a single master. In this way, the costs for wiring and implementation are significantly reduced in comparison with analog technology.