Gas density sensor For gas density, temperature and pressure of insulating gases Model GD-20 with Modbus® or analogue 4 ... 20 mA signal WIKA data sheet SP 60.77 ■ Permanent monitoring of the relevant gas condition parameters in closed tanks ■ For internal and external SF6-insulated equipment ■ Density measurement of alternative gases in electrical 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 Fig. left: Model GD-20-D, plastic circular connector Fig. centre: Model GD-20-D, metal circular connector Fig. right: Model GD-20-A, metal circular connector Description 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. Changes in pressure resulting from thermal effects will be compensated by this and will not affect the output value. 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]) or SF₆ gas density in g/l. 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 ex-works for any defined gas mixture consisting of SF₆, N₂, CF₄, O₂, CO₂, 3M™ Novec™ 4710, He and Ar. The calculation is based on the partial pressure method of the individual gas components. WIKA data sheet SP 60.77 ∙ 01/2022 Data sheets showing similar products: Transmitter for density, temperature, pressure and humidity of SF6 gas with Modbus output; model: GDHT-20; see data sheet SP 60.14 Transmitter for gas density, temperature and pressure of SF₆ gas with Modbus output; mode

1) Specifications apply to measurement of the compensated pressure over the entire temperature range from -40 ... +80 °C [-40 ... +176 °F]; valid only for pure SFe gas. Accuracy is achieved after a maximum of 60 minutes operating time.

Suitable for the following gases Gas mixtures and components can be individually configured and combined ex-works. The calculation is based on the physical principle of the partial pressure method. The gas mixture cannot be changed subsequently. WIKA data sheet SP 60.

Electrical connection analogue version (model GD-20-A) ■ Circular connector M12 x 1 metal (5-pin) ■ Circular connector M12 x 1 plastic (5-pin) WIKA data sheet SP 60.77 • 0

■ Gauge pressure based on 1,013 mbar at 20 °C [68 °F]: bar, MPa, kPa, psi, Pa, N/cm2 ■ Gauge pressure based on 1,013 mbar: bar, MPa, kPa, psi, Pa, N/cm2 Absolute pressure at 20 °C [68 °F] or gas density in g/l for SF6 gas as 4 ... 20 mA current signal WIKA data sheet SP 60.77 • 01/2

Approvals Logo European Union EMC directive EN 61326 emission (group 1, class B) and immunity (industrial application) RoHS directive Manufacturer's information and certificates Logo - China RoHS directive For approvals and certificates, see website Dimensions in mm [in] Examples of analogue versions, model GD-20-A Circular connector M12 x 1, metal version, G 1/2 B WIKA data sheet SP 60.77 ∙ 01/2022 Field case

Examples of digital versions, model GD-20-D Circular connector M12 x 1, metal version, G 1/2 B Circular connector M12 x 1, plastic version, adapter DN 6 Circular connector M12 x 1, metal version, adapter DN 8 Circular connector M12 x 1, plastic version, G 1/4 B WIKA data sheet SP 60.77 ∙ 01/2022

Compensated pressure range / Accuracy / Gas mixture / Process connection / Electrical output / Optional version © 08/2020 WIKA Alexander Wiegand SE & Co. KG, all rights reserved. The specifications given in this document represent the state of engineering at the time of publishing. We reserve the right to make modifications to the specifications and materials. WIKA data sheet SP 60.77 • 01/2022 iWIKAll WIKA Alexander Wiegand SE & Co. KG