H4Tu-R Span Power; H4Tu-R Local Power; Figure 3. H4Tu-C Span Powering Diagram - ADTRAN HDSL4 Installation And Maintenance Manual

Installation Guidelines
Disabling the span power removes all voltage from the HDSL4 loop.
This results in an absence of sealing current which could have an
adverse effect on circuit continuity over an extended period of time.
The H4TU-C uses a DC-to-DC converter to derive its internal logic and span powering voltages
from the –48 VDC office supply. The H4TU-C can span power three modules (an H4TU-R and
up to two H4Rs as listed above) by applying –190 VDC power to the local loop. The span
powering voltage is less than –200 volts with GFI protection to less than 5 mA. The span
powering supply is current limited to approximately 150 mA.
Refer to Figure 3. The differential span power output voltage is measured between Loop 1 and
Loop 2 (reference to Loop 1) and is typically –185 VDC. Loop 1 shows a typical voltage of –6
VDC with respect to ground potential, while the Loop 2 potential is typically –191 VDC with
respect to ground potential.
TC PAM
HDSL4

H4TU-R Span Power

The H4TU-R P/N 1223426L2 receives span power from the H4TU-C.

H4TU-R Local Power

In some circumstances a locally powered remote unit is required. The H4TU-R P/N
1223424L2 can meet those needs.
6
HDSL4 for General Distribution Installation and Maintenance Practice
CAUTION
LOOP 1
(-6 VDC)
SPAN POWER
REGULATOR
SPAN CURRENT
LOOP 2
(-191 VDC)

Figure 3. H4TU-C Span Powering Diagram

pin 26 (220)
101 (DDM+)
K (3192)
pin 27 (220)
102 (DDM+)
9 (3192)
-185 VDC
pin 34 (220)
105 (DDM+)
F (3192)
pin 35 (220)
106 (DDM+)
6 (3192)
61223HDSL4L2-5C