On the main alarm panel, there are two GROUND
INDICATOR LAMPS (fig. 1-27) to indicate the
presence of a ground in the alarm system. All shipboard
alarm panels and remote sensors are electrically isolated
from the ships ground.
The only exception is the
ground fault detector, which is connected to ground for
ground monitoring. If one of both lamps light, you
should have the alarm SWBD and its remote sensors
The AUDIBLE SILENCE CONTROL is a two-position
switch that permits silencing (VISUAL POSITION) the
audible alarm on the main panel. The ALARM lamp on
the main panel is lighted when the AUDIBLE SILENCE
CONTROL is placed in the VISUAL position, and the
system is in an alarm condition.
The lower half of the alarm panel (fig. 1-27) holds
the alarm modules that are connected through the alarm
panel to the remote sensors. On the panel depicted,
there are only five alarm modules used while the rest is
blanked off with covers. Should additional remote
sensors be installed at a later date, a new alarm module
is plugged into the lower panel for each sensor installed.
Each alarm module includes a center-divided lighted
display. Either half can independently display a steady
red light, a flashing red light, or no light, depending upon
the circuit logic. The six possible combinations of alarm
module lights and the appropriate audible alarm are
shown in figure 1-28. Located on the lower half of each
alarm module is a four-way position switch that allows
you to place the individual alarm module in the
NORMAL. This is the normal operation mode.
With the sensor contacts open, the upper indicator lamp
in the module will be on steady while the lower lamp is
off. If an alarm condition occurs, the sensor contacts
will close; the upper lamp will then flash while the lower
lamp remains off and an alarm command from the
module actuates a tone generator, producing a wailing
alarm. If the sensor loop is open-circuited, with the
selector switch in the normal position, the alarm module
signals a supervisory failure; in this case, the upper lamp
will be off while the lower lamp will be steadily on, and
the tone generator will come on, producing a pulsating
This is the position for
acknowledging an alarm. If the selector switch is
moved from the normal to the standby position during
an alarm condition, both the upper and lower indicator
lamps will be steadily on and the audible alarm will be
silenced. When the alarm condition is cleared with the
selector switch in the stand-by position, the lower lamp
changes to a flashing mode and the upper lamp goes out.
Also, a command is fed to the tone generator, producing
a pulsating alarm. This pulsating alarm signal informs
the operator that the selector switch should be returned
to the normal position.
C U T O U T . With the selector switch in the
CUTOUT position, the upper lamp is out while the
lower lamp is steadily on. In this position, power is
removed from the sensor loop to facilitate maintenance.
TEST. This selector switch position simulates an
alarm condition. The upper indicator lamp will flash
while the lower lamp will remain off. A wailing alarm
Your proper response to the coolant alarm SWBD
could mean the difference between a small service
problem or the markings of a much larger disaster. For
example, the COOLANT SUPPLY EXPANSION
TANK LOW-LEVEL alarm module senses a low
coolant level in the expansion tank, immediate action
must be taken. If the tank should empty, the pump will
draw air into the lines and force it throughout the
secondary cooling system.
This would require
additional maintenance to correct the problem.
An improperly maintained liquid cooling system
can cause a major disaster in your waveguide system, if
it is liquid cooled. The damage caused by waveguide
flooding can easily run into thousands of dollars and
include the expenditure of hundreds of manhours by
Various components of high-powered radars, such
as dummy loads, load isolators, and circulators are
cooled by the use of liquid coolant. These components
use a ceramic plug (or disk) in a water-cooled load.
Transmitted rf energy passes through the plug and is
absorbed as heat by liquid coolant flowing through the
load. The plug acts as a window for rf energy, and at the
same time, forms a watertight seal between the
waveguide and the coolant jacket of the load.
Particles of oxidation and dirt from a dirty coolant
system can buildup on the coolant side of the ceramic
plug. The buildup can create an impedance mismatch
or hot spot. This condition can generate an arc, which
carbonizes the ceramic plug so that coolant can leak
through or around the carbonized plug.
Since a nominal 80-psig pressure differential exists
between the coolant in the load and air in the waveguide,
coolant can flow from the water load into the
waveguide, resulting in waveguide flooding. Once the