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Transmitter with Modbus Output - GDHT-20
Brand: WIKA Instruments Ltd.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
Brand
Measuring Ranges
- Dew point at ambient pressure: -50 ... +30° C
- Density: 0 ... 60 g/litre (8.87 bar abs. SF6 gas at 20° C)
- Temperature: -40 ... +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
- max. 0.5 W (max. 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
- DN20, female thread
- G ½ B, male thread
- Malmkvist
- G 3/8 JIS
- M10 x 0.5
- Via measuring chamber (see page 5)
- DN8, female thread
- Other connections on request
- Flange D40
Case
- Stainless steel
Permissible Air Humidity
- ≤ 90 % r. h. (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
- approx. 0.40 kg
