Nortel Modular ICS 7.1, Инструкция по установке

Страница: 204 / 700

204
/ Planning the installation
Modular ICS 7.1 Installer Guide N0130943 02
Internal wiring requirements
The following section describes the cable required for the
Norstar loop and an ISDN S reference point S loop.
Norstar loop
å
one, two or three twisted pair cables per telephone
å
dc loop resistance of less than 64
Ω
å
cable length (0.5 mm or 24 AWG) less than
300 m (1000 ft.)
å
use of a station auxiliary power supply (SAPS) for loops
300 m (1000 ft.) to 790 m (2600 ft.). The SAPS must be a
Class 2 power source that is UL listed and CSA certified.
å no bridge taps
ISDN S reference point (S Loop)
å no longer than 1000 m (3,200 ft.) for point to point
å no longer than 450 m (1,475 ft.) on a point-to-multipoint
extended passive bus
Tips -
The following combinations are not supported with
the MICS 7.1 and MICS-XC 7.1 systems:
• two 2-port expansion cartridge system (four fiber ports
total)
• a six-port and a two-port expansion combination
(eight fiber ports total)
In a fully expanded system using 72 digital channels, consider
installing two service cartridges to prevent blocking of
incoming calls due to lack of DTMF resources, as there are
only four DTMF tone receivers per cartridge.