Mdf Cabling - Samsung DS 616 Technical Manual

DS 616
TECHNICAL MANUAL
Failure to provide an adequate ground may cause a safety hazard, confusing trouble
symptoms or even circuit card failure.
WARNING: Unplug the power cord from the AC outlet before attempting to connect
the ground. Hazardous voltage may cause death or injury. Observe extreme caution
when working with AC power. Remove champ connectors from trunk cards.
What the above paragraphs mean is when conventional analog telephone circuits are
connected to the DS 616 system, under fault conditions (i.e., the tip and/or ring
conductor is crossed with a power line, or the circuit is affected by lightning during a
storm), it is possible for hazardous potentials to appear across the tip and ring wiring
coming into the DS 616 cabinet(s) from the outside plant (i.e., overhead cables, buried
cables, cable head pedestal). These circuits are provided with both primary and
secondary protection circuitry which will attempt to drain off these high voltages and
currents to earth ground. Obviously, it is important to have a good source of ground
connected to the DS 616 system to drain this energy off. Also, certain metallic analog
circuits (e.g., E & M trunks) require a current flow to earth ground to accommodate
normal operating conditions and/or to resolve fault conditions. Again, a good earth
ground source is required by the DS 616 system.
The DS 616 system has two ground reference points. One point is via the green wire in
the power cord connected to the AC power outlet. This ground connection is provided
to meet local electrical codes when the AC ground is required to be common with the
earth ground. However, this can be disconnected either intentionally or unintentionally.
Consequently, a more permanent ground connection is required by connecting a high
current/voltage capacity ground wire which is bonded to ground at the electric service
power entrance or via some other method approved by the National Electrical Code to
the DS 616 system ground lug. This is a more secure ground connection, which can
only be disconnected intentionally. These precautions are taken for safety reasons to
protect personnel working on the DS 616 system and also for operational reasons to
accommodate ground return and/or ground-referenced analog telephone circuits,
which require this solid earth ground connection for normal functioning.

2.5 MDF CABLING

All connections to the DS 616 system are made by way of a customer-provided main
distribution frame (MDF). The KSU is connected to the MDF using one 25 pair, female
amphenol-type cable and a 4-pair modular plug (RJ-45) plus cable (for connection of
the Single Line Telephones). These cables can be routed into the KSU cabinet from
below.
Use one pair twisted jumper wire to cross-connect stations or lines to their associated
port.
(Figure 2–2)
2.4
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PART 2 JUNE 2002
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