User`s guide
Chapter 4 ________________________________________________________________  Installation 
NOTE 
Always use cables that meet the minimum dimension requirements. Long 
cables with thin wires cause power losses in the cable and significantly 
decrease the heating capabilities of WMT700. 
Loop resistance of 0.15 Ω results in 
approximately 1 V drop in heating 
voltage with 200 W heating. You should note this to get proper heating 
capability. For example, the loop resistance of a 10 m cable (227568SP) 
is 0.7 Ω resulting in an approximately 4 V drop. It is recommended that 
you use
 at least a 28 V supply for the maximum heating capability. 
Upgrading from WS425 to WMT700 
When upgrading to WMT700, you have the following installation 
options: 
-  Basic installation procedure, which consists of mounting 
WMT700 with the FIX70 mounting kit and the WMT700 
mounting adapter. 
To upgrade to WMT700 according to this procedure, uninstall 
the WS425 wind sensor and mounting kit and follow the 
installation instructions in section Installation on page 57. 
-  Retrofit installation procedure, which consists of mounting 
WMT700 with a WS425 mounting kit and the WMT700 
mounting adapter for FIX30/60. 
At the measurement site, you need to mount WMT700 and 
connect it to the power source and data acquisition system. 
After upgrading to WMT700, it is possible to install the optional 
bird prevention kit available for the wind sensor. For more 
information, see section Bird Cage on page 31. 
WARNING 
To protect personnel (and the wind sensor), install a lightning rod with 
the tip at least one meter above WMT700. The rod must be properly 
grounded, compliant with all local applicable safety regulations. Do not 
install the 
wind sensor above the top of the lightning protection rod. 
WARNING 
Do not install WMT700 when there is a risk of thunderstorm or lightning 
activity in the area.
VAISALA ________________________________________________________________________ 89 










