Electrical Alarm, Safety, and Warning Systems

condition, the upper display lamp will go out, the

communication systems provide audible and visible

signaling devices to safeguard machinery and

lower display lamp will come on, and a steady alarm

tone will sound.

personnel.

STANDBY MODE.-- The STANDBY mode is

HIGH-TEMPERATURE ALARM

used to acknowledge an alarm. During an alarm

SYSTEM (CKT F)

condition, the mode switch is shifted to STANDBY to

silence the audible alarm. The upper display lamp will

Circuit F provides a means of detecting and

stop flashing and remain on, and the lower display

warning of the presence of overtemperature or smoke

lamp will come on and remain on. When the alarm

in compartments requiring continual supervision; that

condition is cleared, the lower display lamp will begin

is, ammunition spaces, flammable stowage areas,

flashing, and the upper display lamp will go out. The

living spaces, or other spaces designated by ship's

alarm module sends a signal to the tone generator and

design. This system is classified as semivital readiness

a steady tone will sound on the loudspeaker. The mode

class 1.

switch is then returned to the NORMAL mode to

silence the alarm.

Figure 9-16 illustrates a high-temperature alarm

circuit using a mercury thermostat as the sensing

CUTOUT MODE.-- The CUTOUT mode is used

device. This system is of the supervisory closed-

when maintenance needs to be performed on a line. In

circuit type, whereby each detector line and associated

this mode, power is disconnected to the individual

relay coils on the high-temperature alarm switchboard

line, the upper display lamp will go off and remain off,

form a closed circuit, which is under continuous check

and the lower display lamp will come on and stay on.

for grounds, open circuits, low temperature, or the

There is no audible signal associated with this mode.

normal function of the system.

The position of the mode switch disconnects power

from the sensor circuit to allow maintenance to be

The presence of smoke or a rise in the temperature

performed.

within the compartment to a predetermined temper-

ature (105F, 125F, or 150F) will create a bridge on

TEST MODE.-- The TEST mode is used to

the line that will actuate an alarm module in the

simulate an alarm condition. In this mode, the upper

high-temperature alarm switchboard. The nameplate

display lamp will flash continuously, a wailing tone

on the alarm signal designates the compartment in

will sound, and the lower display lamp will remain off.

which the alarm condition exists.

Power supplies furnish operating power to the

An extremely low temperature in a compartment

alarm modules, their sensors, and to a common circuit

or open circuit in the line will result in a failure of the

board in the common alarm section. The power

supervisory current, causing a supervisory alarm on

supplies consist of one transformer and one bridge-

the switchboard.

type diode rectifier for each 10 alarm modules. The

output voltage is approximately 6.3 volts rms.

GAS TURBINE AND DIESEL GENERATOR

A power failure alarm will sound if a primary

HIGH-TEMPERATURE ALARM AND

power failure occurs. A battery in the alarm

FLAME DETECTION SYSTEM (CKT 1F)

switchboard operates the power failure alarm upon

loss of primary power. The battery is float charged by

Circuit IF provides a means for alarm signals to

a taper charger while primary power is applied. The

indicate high temperatures and detection of flame

alarm switchboard is inoperative unless the battery is

within the acoustical module enclosures for gas

connected. A power failure is indicated when the

turbine and diesel generators. This system is classified

upper and lower module lamps are out, and a pulsating

as semivital readiness class 1.

tone is heard from the alarm speaker.

To serve each gas turbine, two temperature

switches are located in the acoustic cell and three

ELECTRICAL ALARM, SAFETY, AND

flame detectors are located at critical points about the

WARNING SYSTEMS

gas turbine. A manual push button is located adjacent

to the enclosure access. In addition, door switches are

The following sections will describe the various

installed at the enclosure access and vent fan control

alarm and warning systems that you, as an IC

switches are provided at the local operating station and

Electrician, will be involved with. These interior

at the propulsion control console (PCC).

9-21