Cambium PTP 670 Series, Руководство пользователя

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Chapter 3: System planning Site planning
Page 3-14
ODU wind loading
Ensure that the ODU and the structure on which it is mounted are capable of withstanding the
prevalent wind speeds at a proposed PTP 670 site. Wind speed statistics should be available
from national meteorological offices.
The ODU and its mounting bracket are capable of withstanding wind speeds of up to 325 kph
(200 mph).
Wind blowing on the ODU will subject the mounting structure to significant lateral force. The
magnitude of the force depends on both wind strength and the variant of the ODU. Wind
loading is estimated using the following formulae:
•
Force (in newtons) = 0.5 × ρ × V
2
× A × C
d
o
“ ρ ” is the density of air = 1.225 kg/m 3 ,
o
“V” is the wind speed in meters per second,
o
“A” is the projected surface area of the ODU in square meters, and
o
“C
d
” is the drag coefficient = 1.385.
The drag coefficient has been measured when the cover plate or antenna is perpendicular to
the air flow.
Applying this formula to the PTP 670 ODUs at different wind speeds, the resulting wind
loadings are shown in
Table 59
Table 59 ODU wind loading (newtons)
Type of ODU Max surface area
(square meters) Wind speed (kilometers per hour)
225
250 275 300 325
Integrated 0.130 431 N 532 N 644 N 766 N 899 N
Connectorized 0.062 205 N 254 N 307 N 365 N 429 N
Equivalent results in US customary units are shown in
Table 60 .
Table 60 ODU wind loading (pounds force)
Type of ODU Max surface area
(square feet) Wind speed (miles per hour)
140 155 170 185 200
Integrated 1.40 97 lb 119 lb 143 lb 170 lb 198 lb
Connectorized 0.67 46 lb 57 lb 68 lb 81 lb 95 lb
If an external antenna is installed, add the wind loading of the antenna to that of the ODU. The
antenna manufacturer should be able to quote wind loading.
Hazardous locations
Check that the ODUs will not be exposed to hazardous gases, as defined by HAZLOC (USA) and
ATEX (Europe) regulations.