Determining Current Requirements For Agiven System Configuration - Siemens System 3 Manual

2. DETERMINING CURRENT REQUIREMENTS FOR A
GIVEN SYSTEM CONFIGURATION
a. Following the format of the Power
Calculation Sheet above, list the
correct quantity for each type of
equipment included.
b. Multiply the supervisory and alarm
currents shown for each item by the
number of modules included, and list
the total module alarm currents in the
appropriate columns.
c. Add the two columns and record the
subtotals where indicated (a and b).
3. BATTERY BACKUP POWER
The US Coast Guard requires that two
sources of power be available to the smoke
detection system. Usually this will be the main
and standby generators. Present requirements
for battery power as a second source call
for 36 hours for passenger ships and 18 hours
for all other ships. When battery backup is
optionally used in addition to main and
standby generators, there is no operation
time requirement, but 18 hours would be
recommended.
System 3 equipment includes two compatible
battery modules:
BT-33 5 AH Battery Module
BT-34 10 AH Battery Module
Section VI — Power Calculations
d. The current requirements of the
audible devices must also be calcu-
lated, based on number and type used.
Fill Blank c in with the amount of
current needed for the audible
devices included.
e. Add the current subtotals (a and b) to
the audible devices current require-
ments (c) to obtain the TOTAL current
necessary for the system. Enter that
amount opposite TOTAL.
Batteries of 28 AH are also compatible with
System 3 systems, Model No. BTX-1. (See
Spec Sheet Catalog No. 3361.)
The following battery load curves show
alarm and supervisory current available
from 5 AH, 10 AH, and 28 AH batteries for
24 hour supervisory current and 5 minute
alarm current capabilities. The supervisory
current is represented on the vertical axis in
milliamps, and the alarm current, on the
horizontal axis in amps.
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