Product guide

39
Humidity and Dew-Point Instruments
Please note: Michell Instruments adopts a continuous development program which sometimes
necessitates specifi cation changes without notice. Please contact us for latest version.
www.michell.com
Environmental Control
WM261
Digital Relative Humidity & Temperature Transmitter, Wall Mount
The WM261 has been developed for high precision
measurement of relative humidity and temperature. This
transmitter is available with a range of outputs.
Highlights
• Designed for accurate measurement in a controlled
environment
• Temperature output scaling confi gurable on request
• Linearization for a specifi c isotherm on request
Accessories and Spare Parts
You can check your hygrometer with the Control Kit HKC
which is based on the principle of non-saturated salt
solutions. Refer to technical data sheet CONTROL KIT
HKC
Technical Specifi cations
Performance
Measurement range (RH) 0–100% RH
Measurement range (T) -20 to +80°C (-4 to +176°F)
Accuracy at 23°C (73°F)
Humidity
<±2% RH (5–95% RH)
Accuracy at 23°C (73°F)
Temperature
Pt100 1/3DIN direct ±0.2°C (±0.36°F)
Current output ±0.3°C (±0.54°F)
Stability – RH sensor <±1% RH/year
Response time 10 sec typical (for 90% of the step change)
Electrical output/input
Output signal (RH)
confi gurable on request
4–20 mA
0–1, 0–5, 0–10 V
Output signal (T)
confi gurable on request
4–20 mA
3-wire 1/3 DIN Pt100 direct
0–1, 0–5, 0–10 V
Supply voltage Output 4–20 mA:
Output 0–10 V:
Output 0–5 V:
Output 0–1 V:
V + = 12–30 V DC
V + = 15–30 V DC
V + = 10–30 V DC
V + = 8–30 V DC
Load resistance
Output 4–20 mA:
Output 0–10 V:
Output 0–5 V:
Output 0–1 V:
Rload < (Uv-9) / 0.02
R > 10 k 
R > 5 k 
R > 1 k 
Current consumption 2 x 20 mA max
Operating conditions
Operating temperature
Probe
Housing
Storage
-30 to +85°C (-22 to +185°F)
-30 to +70°C (-22 to +158°F)
-40 to +70°C (-40 to +158°F)
Mechanical specifi cation
Ingress protection IP65 (NEMA 4 level)
Housing material PPO + POM
Dimensions
Housing
Probe
80 x 80 x 34mm (3.15 x 3.15 x 1.34”)
L=85mm, ø12mm (L=3.35”, ø0.47”)
Weight 100g (3.53oz)
Electrical connections Screw terminals
Dimensions
Issue No: WM261_97184_V2_UK_1110