Permanent monitoring
In order to prevent system failures in switchgear and network outages, the permanent monitoring of the gas density is essential.

The model GD-20 calculates the current gas density from the pressure and temperature using a complex virial equation in the gas density sensor´s powerful microprocessor. Pressure changes resulting from thermal effects will be compensated by this and will not affect the output value.

MODBUS^® fieldbus
The RS-485 interface communicates using the MODBUS^® RTU protocol. The instrument's output parameters and their units can be configured and read according to requirements.The GD-20 model can be freely configured at the factory for any defined gas mixture consisting of SF₆, N₂, CF₄, O2, CO₂, 3M™ Novec™ 4710, He and Ar.

Applications

• Permanent monitoring of the relevant gas condition parameters in closed tanks
• For internal and external SF_⁶-insulated equipment
• Density measurement of alternative gases in electrical equipment or in the laboratory

Special features

• High-accuracy sensor technology
• Digital MODBUS^® RTU or analogue 4 … 20 mA output signal
• IP67 ingress protection, optionally with IP6k9k field case
• Very good long-term stability and EMC characteristics
• Compact design

The calculation is based on the partial pressure method of the individual gas components.

Signal stability
Due to its high long-term stability, the sensor is maintenance-free and requires no recalibration. Due to the hermetically sealed weld seam and a measuring cell design without sealing elements, the permanent sealing of the measuring cell is ensured.

The gas density sensor is also available with analogue output signal (4 … 20 mA) for output of the compensated pressure (p at 20 °C [68 °F]).