User guide

The EDA Components
36 1/1551-HSC 901 35/3 Uen C 2005-12-02
Remote site
190V-380V/48V
DC/DC Converters
Remote Unit
Central Office
Flatpack
Remote Power System
+190
48V to DSLAM
Cable length
[m, km, kft]
Line impedance
[Ohm]
Vco
[V]
Vremote
[V]
I [mA]
VA limit
VA limit
GND
-190
VA limit
DC/DC
converter
-48 to
±190
1
5
1
12
Figure 27 Block diagram for the remote powering
Figure 27 on page 36 shows a block diagram of the remote powering
system.
The DC/DC converter is a 1500-watt step up converter which provides
±190 V DC from a traditional –48 V DC source. The VA limiter distributes
the ±190 V DC and provides a safe power distribution over existing twisted
pairs, protecting the Remote Feeding Circuits (RFT) from over-voltage,
over-current, and leakage current to ground. The VA limiter has 12
individual outputs of up to 100 W each (RFT-V).
The converters at the remote site consist of parallel DC/DC converters that
terminate the twisted pairs being fed from the Central Office. The
converters incorporate high-energy surge protection and one specifically
designed to work with a limited power source (VA limiter) and fed over a
high-impedance line. The modules can be paralleled to meet the power
requirement at the Remote End.