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Technical Product Manual - DCT1900
Configuration Directions, Base Station Powering
4-8 Config-DCT1900/R8/mw
© 2000-2005
4.5 Alternative for Calculating the Power Consumption per Base Station
In Figure 4–4 the power consumption of the Base Station and the cabling is given as a function of
the cable length in terms of percentage. This relation is almost independent of the number of cable
pairs, cable resistance and supply voltage. Table 4–5 also gives this relation in steps of 5 percent.
The table can be used as follows.
Fig. 4–4 Power Consumption from Power Supply Related to Cable Length
Example
z supply voltage : 48V
z number of EPP (Express Powering Pairs) : 0
z wire size : 24 AWG (R
tp
=0.055 /m)
z length : 820 ft.
With this information the maximum cable length can be read from Table 4–2. The maximum length
can also be calculated using the formulas in Paragraph 4.4. When using these formulas, you must
use n=2 for the number of pairs (2 data pairs, no express powering pairs). With both methods the
result is 2763ft.
The length of the cable is (820/2763) 100%+29.7% of the maximum cable length. Round up this
value (30%) and read the dissipated power from Table 4–5. The dissipated power is 8.3W.
75
0
15
100%
Maximum cable length
Power required from power supply (Watts)