Installing Emergency Transfer Units And Terminals; 574-5 Power Transfer Unit - AT&T 75 Wiring Manual

Z100-TYPE HARDWARE

Installing Emergency Transfer Units and Terminals

Requirements—Terminals
Emergency transfer capability is provided by the transfer unit located in the cable access
panel. Additional transfer units can be mounted alongside or above a CAP when the number
of transfer units required exceed the number of CAPS.
Only 500- or 2500-type voice terminals can be used for emergency transfer. For R1V2 or
R1V3 systems, the 500-type and 2500-type terminals can also be used as normal extensions.
For R1V1 systems, the 500-type terminals are used when the central office has rotary dialing
service only and cannot be used as normal extensions. Emergency transfer capability may
be provided on Central Office (CO) and Wide Area Telecommunications Service (WATS)
trunks.
The following two types of transfer units are available:
Z1A Emergency Transfer Unit—Each unit serves up to six Power Failure Transfer
terminals. A ground-start switch is required at each preselected voice terminal when
ground start trunks are used.
574-5 Power Transfer Unit—Each unit serves up to five Power Failure Transfer
terminals. The unit provides automatic ground start.
The preinstalled units are connected to the EM XR terminal row in the cable access panel.
The units are powered (-48 V dc) from the EM TRANS POWER terminals located on the 1C
connector of the first (top) cable access panel. There are seven EM TRANS POWER
terminal pairs. This simplifies powering of up to seven emergency transfer units.

574-5 Power Transfer Unit

The 574-5 Power Transfer Unit has connection for five emergency transfer terminals and is
compatible with both loop start and ground start trunks. Ten slide switches in the center of
the unit (Figure 2-87) are set for the trunk type (two per trunk). The switches are set at the
factory for ground start trunks as shown in Figure 2-87.
When ground start trunks are used, the transfer unit will automatically provide ground start
for each trunk without the need for special wiring at the terminal used for emergency
transfer service.
Figure 2-88 shows wiring required at first (top) cable access panel for a voice terminal used
only for emergency transfer. These terminals are always connected from the port side of the
cross-connect field to connector X at the cable access panel. Figure 2-89 shows wiring
required at first cable access panel for a voice terminal used for emergency transfer as well
as a normal extension. Wiring at other cable access panels is the same for both type
installations except the power (PWR) leads must be connected to EM TRANS POWER
terminals on the first cable access panel.
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