Transmitter with Modbus Output - GDHT-20

Brand: WIKA Alexander Wiegand SE & Co. KG

The model GDHT-20 transmitter is a multi-sensor system with digital output for the measurement parameters of pressure, temperature and humidity. Based on these measured values, the condition-related data can be determined.
Features
  • High-accuracy sensor technology. 
  • MODBUS output protocol via RS-485 interface. 
  • Ingress protection IP 65. 
  • Very good long-term stability and EMC characteristics. 
  • Compact dimensions. 

Specifications

Measuring Ranges

  • Dew Point at ambient Pressure: -50° to +30° C
  • Density: 0 ... 60 g/litre (8.87 bar abs. SF6 gas at 20° C)
  • Temperature: -40° to +80° C
  • Pressure at 20° C: 0 ... 8,87 bar abs. SF₆ Gas
  • Pressure: 0 ...16 bar abs.
  • Burst Pressure: 52 bar abs.
  • Overload safety: up to 30 bar abs
  • Pressure reference: Absolute

Accuracy

  • Specifications only valid for Clean Gaseous SF6
  • Dew Point: ± 3 K
  • Density: ± 0.60 %, ± 0.35 g/litre (-40 ... 80° C)
  • Temperature: ± 1 K
  • Pressure: ± 0.20 %, ± 32 mbar (-40 ... < 0° C), ± 0.06 %, ± 10 mbar (0 ... 80° C)

Long-term Stability at Reference Conditions

  • Temperature: ≤ ± 0.10 % of Span/Year
  • Pressure: ≤ ± 0.05 % of Span/Year
  • Dew Point: ≤ ± 0.50 % of Span/Year

Refresh Rate

  • Density: 20 ms
  • Temperature: 20 ms
  • Pressure: 20 ms
  • Dew Point: 2 s (Typical), auto-Adjustment cycle every 30 min.

Power Supply UB+

  • DC 17 ... 30 V

Power Consumption

  • Maximum 0.5 W (Maximum 3 W during the Heating phase of the humidity Sensor)

Electrical Connection

  • Circular Connector M12 x 1 (5-Pin) Modbus RTU via RS-485 interface

Functionality Modbus

  • Mixture ratio of SF6 to N2 or CF4 (Default 100 % SF6 gas) Customer-specific Sensor name

Measured Values with Alternative Units Can be Retrieved Directly in the Modbus Registers.

  • Pressure: mbar, Pa, kPa, MPa, psi, N/cm², bar (At 20° C)
  • Humidity: ppmv, ppmw
  • Dew Point: °C
  • Freezing Point: °C
  • Relative Humidity: %
  • Temperature: °C, °F, K
  • Density: g/litre, kg/m³

Process Connections

  • G 1 B, Male thread, Stainless Steel
  • DN 20, Female thread
  • G 1/2 B, Male thread
  • Malmkvist
  • G 3/8 JIS
  • M10 x 0.5
  • Via measuring chamber (see page 5)
  • DN 8, Female thread
  • Other Connections on Request
  • Flange D40

Case

  • Stainless Steel

Permissible Air Humidity

  • ≤ 90 % Relative Humidity, Non-Condensing

Ingress Protection

  • IP65, only when plugged in and using mating Connectors with the corresponding ingress Protection

Electrical Safety

  • Protected Against Reverse Polarity, Protected Against Overvoltage

Dimensions

  • Diameter: 48 mm
  • Height: 96 mm

Weight

  • Approximately 0.40 kg

  • Permanent monitoring of the relevant gas condition parameters in closed tanks
  • For indoor and outdoor SF6 gas-insulated equipment

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