Michell Instruments WM281, Руководство пользователя

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WM281/291 User’s Manual
Michell Instruments 1
INTRODUCTION
1 INTRODUCTION
The 280/290 Series Transmitters are microprocessor-based instruments used to measure
relative humidity and air temperature.
These products are available in four different model types:
• WM281/WM291 Premium Wall Mount Transmitter range
• DT282/DT292 and DT284/DT294 Premium Duct Mount Transmitter range
• WR283/WR293 Premium Wall Mount Remote Transmitter range
• PR285 Premium Pressurized Remote Transmitter range
This manual is for the WM281/291 versions only.
The 280/290 Series Transmitters have two analog outputs for temperature and relative
humidity respectively providing 4-20 mA, 0-20 mA, 0-10 V, 0-1 V and 0-5 V. There is a
third analog output which is calculated providing 4-20 mA, 0-20 mA, 0-10 V, 0-1 V and
0-5 V.
The 290 Series Transmitters are equipped with an LCD display mounted in the cover
of the housing, making it possible to display the temperature, relative humidity and a
value set at the third calculated output.
The key features are:
• Dual voltage or dual 4-20 mA outputs
• Digital RS485 Modbus output
• Traceable calibration certificates
• Interchangeable sensor module
• Optional LCD display
The third analog output is configurable by the user through the Comms Kit or display
version and indicates one of the following calculated values:
Dew point
The temperature at which a mixture of gas and water vapor must be cooled (at constant
pressure) for condensation to begin to form in the liquid phase, i.e. the temperature
at which a gas becomes saturated in equilibrium on a flat surface of water. The unit of
measure is degrees Celsius (°C), or can be set to degrees Fahrenheit (°F).