Coastcom D/I Mux III System, User Manual

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Chapter 3. Installation
54
Grounding:
Protection against safety fault or surge current is provided by connecting the D/I Mux III chassis to the
facility earth ground. Since both safety fault currents and surge events are conducted to earth ground by
this connection, it should be made with a short, direct, heavy grounding conductor, # 10 AWG or heavier.
If not grounded in this manner, an adequate ground may be obtained through the D/I Mux III mounting
ears if the facility equipment rack is securely grounded to the facility earth ground via a heavy, direct
conductor.
References for further study:
Whitham D. Reeve. Subscriber Loop Signaling and Transmission Handbook: Analog . IEEE Press, 1992
Outside Plant Engineering Handbook. Winston-Salem, NC: AT&T Document Development Organization,
January 1990
Telecommunication Electrical Protection. AT&T Technologies, Inc. 1985
System Cabling
Figures 3-8 through 3-11 depict the backplane of the four different D/I Mux III shelves. The F and M
designations in the backplane figures correspond to female and male connectors respectively. Cabling is
connected to the D/I Mux III backplane. Some line cards, such as the Subrate Data Multiplexer (SDM),
premium Subrate Data Multiplexer ( p SDM), Multipoint Subrate Data Multiplexer (MSDM), and Smart
Omni-Orderwire Station cards, also include cabling at their front panels.
The 8-slot D/I Mux III is available in both the DB-25 connector style, and a combination “Universal”
configuration that includes both the two each DB-25 and three each 50-pin connectors.
FCC Radio Frequency Emission Compliance
Electrical connections to D/I Mux III shelves (except terminal block connections) must be made with shielded
cables. To ensure compliance with FCC emission levels, each shield must cover all of the conductors, and
connect along the cable's outside perimeter to the metal shell of the mating connector. Pigtail grounds (or
grounds made to a ground pin instead of the metal shell) will result in inadequate shielding. A ferrite
shielding core, (P/N 0180-0106) looped twice around the backplane terminal block 1 (TB1) and terminal
block 2 (TB2) wiring, is required to limit radio frequency emissions on both the Common Control Unit (CCU),
Multiplexer Control Unit (MCU), and the Advanced Common Control Unit (AMCU). The MCU requires two
additional ferrite shielding cores installed on any RJ-48 cabling connected through its front panel.
In both cases, the appropriate number of ferrite shielding cores is supplied in the kit bag that comes attached
to the D/I Mux III shelf. Proper installation of the cores ensures compliance with FCC Part 15 rules for
limiting radio frequency emissions from the unshielded wires. The terminal block connections are screw
terminals. When wiring the terminal block connections, loop each wire two complete turns through the ferrite
shielding cores as shown in Figure 3-7. Place the cores within five inches of the terminal block.
Warning!
Failure to use shielded cables can result in violation of FCC rules for which the user is responsible.