AT&T System 75, Wiring Diagram

Page: 84 / 345

CHAPTER 3. EQUIPMENT ROOM DESIGN
CHAPTER 3. EQUIPMENT ROOM DESIGN
General
The System 75—System Description (555-200-200) or System 75
XE—System Description (555-201-200) provides equipment room
specifications for temperature, humidity, air purity, lighting levels, and
grounding. They also provide information on the floor and wall space
required for the switch and the associated peripheral equipment that is
to be installed in the equipment room. For completeness, some of the
information contained in these documents is repeated in this guide.
Hardware Equipment Room Applications
In the equipment room, the 66-type/110-type hardware is used for the
cross-connect field which consists of a trunk/auxiliary field and a
distribution field (port, auxiliary, and station).
Trunk/Auxiliary Field
The trunk/auxiliary field contains three distinct cross-connect areas:
●
●
●
The green field terminates the network interface leads (from the
CO) and provides the terminals to cross-connect the CO leads to
the purple or yellow fields as required. A single row of the 66-type
connecting block/110-type terminal block can terminate
twenty-four 1-pair, eight 3-pair, or twelve 2-pair trunks.
The purple field terminates the trunk circuits from the switch with
WP-90929, List 1 or 3 (110-type terminal block) or WP-90929, List
2 or 4 (66-type connecting block) concentrator cables. Also,
25-pair cables can be used to terminate trunk circuits from the
switch with each trunk circuit pack connecting to one 25-pair row
of the 66-type connecting bIock/110-type terminal block. Each
66-type connecting block/110-type terminal block row can
terminate twenty-four 1-pair, eight 3-pair, or twelve 2-pair trunks.
The yellow field provides cross-connection terminals for all
miscellaneous leads from the switch, such as alarm monitors,
emergency transfer relay power, attendant console power, and
3-1