Toshiba STRATA DK24 Manual page 71

INSTALLATION-SYSTEM DESCRIPTION
SECTION 200-096-202
FEBRUARY 1991
IMPORTANT NOTES:
1. Local ordinances may dictate battery
type and installation details.
2. The reserve power batteries must be
installed while commercial AC power
is applied to the system to allow the
power supply reserve relay to operate.
If batteries are connected after AC
power is lost, the batteries WILL NOT
power the system and the system W/L L
NOT operate.
4.20 Battery Charger
4.21
To allow full normal system operation during
a power failure, the power supply has a built-in,
current limiting battery charger that maintains cus-
tomer-supplied batteries. Electrical characteris-
tics of the battery charger include:
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Nominal float voltage: 2.275 volts/cell
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Charge current: 0.7 amps maximum
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Battery discharge cut-off voltage: 20.5 *O.!?V
5 POWER FAILURE/EMERGENCY
TRANSFER UNIT
5.00 The Power Failure/EmergencyTransfer Unit
(DPFT) provides an optional means of ensuring
uninterrupted telephone operation in the event of
a power failure. The DPFT (Figure 2-8) automati-
cally connects selected CO lines to standard tele-
phone lines in the event of a power failure, while
CO LINE
TEL LINE
POWER FAILURE TRANSFER
FIGURE 2-8-POWER FAILURE
TRANSFER UNIT (DPFT)
permitting normal operation when the system is in
service.
5.01
The DPFT is a self-contained module that
mounts externally to the system's KSU, typically
near the MDF. Connections to the CO lines, stan-
dard telephones and the cabinet are made with
two50-pinamphenol-typeconnectorson theDPFT.
5.02 The DPFT consists of eight normally open
relays, connecting the telephones to PSTU (Stan-
dard Telephone Interface Unit) PCB circuits and
the CO lines to PCOU (CO Line Unit) PCB circuits
(Figure 2-9). If a power failure occurs, the relays
close, connecting the telephones directly to the
CO lines. Calls can then be placed from the se-
lected standard telephones, over the CO lines,
completely bypassing the system.
5.03 When the DPFT is reset after a transfer,
existing PFT conversations are protected. Individ-
ual circuits are restored only when they become
idle.
6 PRINTED CIRCUIT BOARD
DESCRIPTIONS
6.00 Twelve types of PCBs are available for use in
STRATA DK systems. A maximum of seven PCBs
can be installed in DK24, nine in DK56, and fifteen
in DK96.
6.01 With the exception of the PCTU and PCTUSl
PCBs, PCB size and connector provisions are
standardized. All PCBs, including the PCTU/
PCTUSl, measure 7.5 x 5.5 in (190 x 140 mm).
The PCBs connect to the KSU's backplane with
identical 40-pin male connectors. Except for the
PCTU/PCTUSl PCBs, the connectors are posi-
tioned in the same location on each board type.
6.02 PCB external connections are made to the
Main Distribution Frame (MDF) using the following
industry-standard connectors:
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25-pair Amphenol Female:
Twenty-five-pair
amphenol connectors connect electronic tele-
phones, standard telephones and most periph-
erals. I
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Modular:
Modular jacks connect CO lines, E &
M TIE lines, the Station Message Detail Re-
2-6