Tunnel application - WMT700

WMT700 Series User Guide

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User guide

In the tunnel application, airflow can be presented with one mA output channel, because airflow goes along the tunnel. Typically, a relatively long average time (time constant) for wind speed parameter is applied.

The sensor must be installed in a tunnel so that the sensor’s North is aligned with the tunnel. The Aout1 channel (x component) provides the airflow in the tunnel. The following figure shows a typical WMT700 installation in a tunnel.

Figure 1. WMT700 in tunnels

The following figure shows the 4…20 mA output as a function of airflow. The zero value is in the middle of the output scale (12 mA). When airflow increases from 0 m/s towards North, mA output reduces from 12 mA linearly resulting in 4 mA with 20 m/s wind. Similarly, when airflow increases from 0 m/s towards South, mA output increases from 12 mA linearly resulting in 20 mA with 20 m/s wind.

Figure 2. mA output in tunnels

The parameter aout_map with setting 1 is used to get the North-South component of wind.

s aout_map,1

The North-South component to Aout1, the current output, -20 ... 20m/s to 4 … 20mA, Aout2 disabled:

s aout1_g,0.0004 
s aout1_o,0.012 s
s aout1minv,0.004
s aout1mode,0
s aout1err ,0.002 s