Power Requirements - Siemens System 3 Manual

It is a US Coast Guard requirement that the
fire detection system have two sources of
power. Most large ships have both main
generators and emergency generators;
therefore, they can satisfy this requirement
by arranging to have power supplied to the
fire detection system by both the main and
emergency generators.
A US Coast Guard approved Power
Transfer Relay must be used for the
automatic transfer from main power to
secondary power when the main power
source has 15% to 20% potential variation.
The transfer to secondary power creates a
visual and audible trouble signal on the CP-
35 Control Panel. The Model PTR-1 Power
Transfer Relay from Siemens Industry, Inc.
has been designed for this purpose and is
US Coast Guard approved.
In cases where there are no emergency
generators, battery backup power to the
system is required. Revised US Coast
Guard regulations have reduced the
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SECTION II

POWER REQUIREMENTS

required battery operation time to 36 hours
for passenger ships and 18 hours for all
other types of vessels. In cases where it is a
desired option to furnish the fire detection
system with standby battery power, even
when there are main and emergency
generators supplying the system, there is no
specific battery operation time period,
although it would be recommended to be a
minimum of 18 hours.
When the smoke detection system is
furnished with battery backup power, it is
necessary to calculate the system power
requirements to determine the battery
ampere-hour capacity necessary. The
calculations can be done on the Power
Calculation Sheet (page 24) and the Battery
Curves shown on pages 26 and 27. Another
requirement involving battery power is that a
voltmeter and ammeter (MM-35) are
furnished. The voltmeter and ammeter are
not required when the batteries are used as
a third power source.