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GDK-100
DIGITAL KEY TELEPHONE SYSTEM
93
3.5 SYSTEM
WIRING
3.5.1 Battery Back-Up Wiring
The system can be equipped with to provide operation from external batteries if commercial AC power fails.
The Back-Up batteries are connected to the connector on the front of the PSU through the battery cable,
which contains two ring terminals and a 4-pin female connector.
The external batteries must provide 24 Volts DC. This is generally accomplished by connecting two 12
volt batteries in a series arrangement. Operation on batteries is controlled by the PSU. This PSU will provide
charging current to the batteries during normal AC power operation at a maximum of about 500 mA. During
battery operation, the battery operation of PSU will be stop if the AC power re-applied or the battery voltage
is too low to maintain proper system operation.
If a low-battery cut-off occurs and a new battery is installed, it is necessary to reset the Battery Back-Up
circuit in PSU manually by momentarily pressing the switch marked as BATT. RESTART located on the
upper side of PSU. (It is not available in SBKSU).
The length of time that the system will operate on the batteries is dependent on several elements
including, battery charging state, condition of the batteries, capacity of the batteries, and the size of the
system (number of station ports). The chart below gives the approximate back-up time for several system
sizes and different battery capacities in ampere-hours.
Battery
Capacity
24 Ports
36 ports
72 ports
20AH
6 hours
4 hours
2 hours
40AH
12 hours
8 hours
4 hours
GDK-100
PSU
FUSE
20A
Figure 3.5.1
Battery Back-up wiring
RED
BLUE
GDK-100 PSU
Front Panel
Note: The cable for the battery connection is supplied with BKSU in the same
package.