supplied from the two battery chargers paralleled with
assembly in the EOS. The throttle assemblies at each
the three battery sets. A secondary emergency power
station are identical except for paint color and the
source is dc voltage supplied from two diesel engine
guarded ENGINE-OFF switch, which is located only in
the pilothouse unit. The throttle assemblies operate in
conjunction with the throttle panel assemblies at each
SHIP'S SERVICE POWER UNITS
station. This feature allows the HBCS to transfer control
of the engines between the helm station and EOS.
The two SSPUs that supply power to the generators
You have just read about the hullborne propulsion
and other PHM electrical equipment are installed in
system. Earlier in this chapter, you read about the
nonadjacent auxiliary engine compartments. The major
foilborne propulsion system. In the following section,
components of an SSPU are shown in figure 7-30. Each
we will discuss the PHM electrical system that allows
SSPU includes a turbine engine and a mechanical
both main propulsion systems to work.
gearbox. Each SSPU must supply the power to drive an
a c generator, two hydraulic pumps, and a load
compressor, all of which are mounted on the gearbox.
PHM ELECTRICAL SYSTEM
Each SSPU is installed by means of a 3-point suspension
and is attached to the ship's structure by means of
The PHM electrical system generates, distributes,
resilient mounts. These mounts are composed of bonded
and controls the craft's onboard electrical power. Two
elastomer spool pieces secured in trunnion blocks.
450-V ac, 400-Hz, 3-phase brushless generators supply
p o w e r to the craft's electrical equipment. These
Normal SSPU control is maintained from the SSPU
generators are driven by power supplied by the ship's
panel located in the EOS. The PHM electrical system
s e r v i c e power units (SSPUs). Switchboards and
allows the SSPUs to operate individually or
distribution panels distribute and control the electrical
simultaneously. When both SSPUSs are operating, each
output. Transformers, converters, and inverters convert
200-kVA, 400-Hz alternator shares the ship's electrical
a portion of the generator output to lower ac and dc
load. Each SSPU is capable of supplying the PHM's
voltages to supply the lower voltage equipment needs.
total electrical load. Reduction in electrical load,
Four shore power receptacles, two for 400-Hz and two
however, is necessary for an SSPU to start the LM2500
for 60-Hz power, are provided to receive power from
GTE.
shore installations or other ships upon need.
Now that you have read about the general purpose
Basic control of the generators is at the EOS, with
and assembly of an SSPU, let's take a closer look at
emergency controls and voltage/amp meters provided
some of its main components.
on each switchboard. As shown in figure 7-29, the EOS
console contains the electrical system indicator and
control panel that displays the voltage, amp, frequency,
and kilowatt output of each generator. This panel also
provides the switches to control and test the entire
electrical system associated with the output of each
individual generator. A dc voltmeter and dc ammeter for
monitoring voltage and current are included on this
panel. Ground fault detection lights and test switches on
t h e panel provide a means of monitoring circuit
condition.
Two battery chargers supply the normal dc power
requirements for the craft. They also provide the voltage
required to maintain the three emergency power battery
sets at a specified charge level. Battery power is used
for normal SSPU and diesel engine starts. The batteries
also supply normal dc power for various control circuits,
indicating circuits, and dc fuel pumps. The batteries are
also used as an emergency power source to supply
Figure 7-30.--Ship's service power unit (SSPU).
e m e r g e n c y loads after an ac voltage failure. For
e m e r g e n c y power, the primary source is voltage
7-33
