Test Operation

signal relay operating and closing its set of contacts.

ALARM SWITCHBOARDS

Figure 9-17 is a schematic of an alarm switchboard.

The alarm switchboard is an electrical system

installed on board ship for the detection and warning

Test Operation

of a variety of important functions or conditions that

require continuous monitoring. It also gives warning

The supervisory alarm system is designed to

when trouble or failure occurs in the alarm circuit and

require very little attention. Almost any trouble that

indicates which section of the equipment is involved.

may affect the system will give both an audible and a

Alarm switchboards are normally used to monitor

visual signal in the form of an alarm, or trouble alarm.

alarm, safety, and warning systems that have sensors

However, the system is arranged so that periodic tests

located in a large number of spaces. The type IC/SM

of all circuits may be made easily and quickly from

alarm switchboard is the latest type of switchboard

the alarm switchboard. These procedures test only the

installed on board ships today and is the only one we

panel and line units. External wiring must be checked

will discuss in this training manual.

at the panel for insulation resistance and continuity.

The type IC/SM alarm switchboard uses

The silent test switch is centrally located at the top

individual line display alarm modules to present

of the alarm switchboard. Keep this switch in the

multiple steady and flashing visual displays together

N O R M A L position except when testing the

with multiple audible signals to indicate the state of

switchboard circuits. For the silent alarm test, place

the sensors associated with each individual line.

the silent test switch in the SILENT ALARM TEST

position. This disconnects the extension signal relay,

The type IC/SM alarm switchboard is available in

that in turn controls the alarm bell and connects the

many different sizes. Figure 9-18 is an illustration of

ALARM TEST light into the circuit in place of the

an IC/SM-50 alarm switchboard. This switchboard is

bell. When the silent test switch is placed in either test

capable of monitoring 50 individual lines. Each

position, the TEST LIGHT on the panel will flash.

switchboard contains a common alarm section and a

line display section. The common alarm section

To test the capacity of each circuit to act as an

includes all components located on the control panel,

alarm, place the silent test switch in the SILENT

as well as the subassemblies common to any size alarm

ALARM TEST position. Place the circuit test switch

switchboard. The line display section contains the

on the line unit in the TEST position. The ALARM

individual display modules, one for each circuit.

TEST lamp will light and the target will show red on

the circuit being tested, If the circuit is in proper

Common Alarm Section

condition to turn off the ALARM TEST light, return

the station to NORMAL.

The upper section of the switchboard is the

To perform the silent trouble test, place the silent

common alarm section. The primary function of the

test switch in the SILENT TROUBLE TEST position.

common alarm section is to interpret commands from

Placing the switch in this position disconnects the

the line display alarm modules and, in turn, generate

trouble buzzer and places the silent test lamp in the

the appropriate audible signals. The audible signals

circuit. As in the silent alarm test, the test lamp will

produced are a wailing (or siren) tone, a pulsating

also flash, Each supervisory circuit is tested by

tone, and a steady tone. Each of these signals

moving the line unit test switch slowly from

represents a particular system condition. An alarm

NORMAL to OFF. The yellow target will show on the

condition activates the wailing tone, the supervisory

line unit directly above the line unit test switch, and

failure activates the steady tone, and a power failure

the TROUBLE TEST lamp on the alarm panel will

activates the pulsating tone.

flash momentarily. The yellow target will show as

long as the line unit test switch is in the OFF position.

The secondary function of the common alarm

The TROUBLE TEST lamp will darken as soon as the

section is to detect and indicate grounds in the

line unit test switch is fully operated. If the yellow

switchboard itself or in any of the individual line

target does not show, the circuit is inoperative and

circuits.

should be repaired.

Mounted on the front of the common alarm section

Upon completion of the silent alarm test and the

are two ground detection indicators, a visual-audible

silent trouble test, take care to see that all test switches

switch, an alarm silence indicator, a dimmer control,

are returned to normal.

a speaker, and a fuse holder. Located inside the

9-15