Watson TDM
Operating Manual
Watson-TDM-Manual-W.doc
Version 2.0-01
5-4
Revision: 2008-02-07
5.3.5 Remote powering reach
The remote power feeding current per pair can be approximated using the follow-
ing formula:
PRUU
P
I
Loopfeedfeed
loop
4
2
2
−+
=
I
loop
feeding current per pair. I
loop
is limited
to 55 mA by the LTU.
U
feed
feeding voltage from LTU (112V)
P Power consumption per pair, i.e. ½ of
the total NTU power consumption on
a two-pair system (and ¼ of total
power consumption for 4-pair NTUs)
R
loop
Ohmic resistance of loop. This in-
cludes the resistance of the copper
loop and the resistance of the feeding
and protection circuits on LTU and
Regenerator.
10
20
30
40
50
60
0 500 1'000 1'500 2'000
Loop Resistance (Ohm)
Feeding current per pair (mA)
P = 1.55 W
P = 1.75 W
P = 2.30 W
P = 2.60 W
P =3.00 W
P = 3.15 W
P = 3.70 W
P = 4.80 W
P = 5.10 W
Current Limit
Voltage Limit
P = 2.45 W
Power
Consumption
per pair
Figure 5-1: Line feed current vs. loop resistance for different values of power
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