High Speed Transmission Equipment
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2002 Teccor Electronics
SIDACtor
Data Book and Design Guide
Component Selection
The P2300SC MC
SIDACtor
device and the F1250T
TeleLink
fuse were chosen because
both components meet GR 1089 surge immunity requirements without the use of additional
series resistance. The P2300SC MC voltage rating was selected to ensure loop powering
up to 190 V. For loop powering greater than 190 V, consider the P2600SC MC. The
P0080SA MC
SIDACtor
device was chosen to eliminate any sneak voltages that may
appear below the voltage rating of the P2300SC MC.
ISDN Circuit Protection
Integrated Services Digital Network (ISDN) circuits require protection at the Network
Termination Layer 1 (NT1) U-interface and at the Terminating Equipment (TE) or
Terminating Adapter (TA) S/T interface. Signal levels at the U-interface are typically ±2.5 V;
however, with sealing currents and maintenance loop test (MLT) procedures, voltages
approaching 150 V rms can occur. (Figure 3.11)
Figure 3.11
ISDN Overview
Protection Circuitry
Longitudinal protection was not used at either the U- or the TA/TE-interface due to the
absence of an earth-to-ground connection. (Figure 3.12) At the U-interface, the
P2600SC MC
SIDACtor
device and F1250T
TeleLink
fuse provide metallic protection, while
the TA/TE-interface uses the P0640SC MC
SIDACtor
device and F1250T
TeleLink
fuse.
Figure 3.12 also shows interfaces not isolated from earth ground.
ISDN Compliant
Central Office Switching
System
Network
Termination
Layer 1
NT1
CO
ISDN DSL
2-Wire,
160 kbps
2B1Q ±2.5 V
U
Reference
TA
TE
NT2
PBX
TE
TA
S
S
S Reference, 4-Wire
T Reference
4-Wire
T
T
T
Terminal
Adapter
Terminal Equipment
(ISDN
Compliant)
POTS
Non-ISDN
Terminal
B1
B2
D
ISDN Terminal
B1
B2
D