| Tweet |
Custom Search
|
|
|
||
 TM 55-1905-223-10
Section III. TECHNICAL PRINCIPLES OF OPERATION
1-9. General. The following paragraphs provide technical principles of operation of the LCU systems.
1-10 Power Generation System The power generation system provides the LCU with primary (240 Vac, 3-
.
phase, 60Hz 250kW) and emergency (240 Vac, 3-phase, 60Hz, 40kW) electrical power (FIGURE 1-29).
Primary power is generated by one of two ship's service diesel generator (SSDG) sets, which supply the main
switchboard and the emergency switchboard through a bus tie from the main switchboard. Emergency power is
generated by an emergency diesel generator set, which supplies the emergency switchboard for continued
operation of vital systems and equipment during loss of primary power. In port, the LCU is capable of receiving
shore power (480/240 Vac) through a shore power cable terminating at a two-connection shore power box. If
available shore power is 480 Vac, the power is selected at the main switchboard through a circuit breaker and
steped won to 240 Vac by three shore power transformers, prior to main switchboard entry. Shore power of 240
Vac is selected at the main switchboard by circuit breaker, and bypasses the 480 Vac transformers. Automatic
bus transfer equipment, located in the emergency switchboard, isolates the emergency switchboard from the
main switchboard upon loss of primary power and allows emergency power to be supplied through the
emergency switchboard.
a.
Ship's Service Diesel Generator EngineTwo diesel generator set engines power individual ship's
.
service generators, which provide primary electrical power throughout the LCU. The port ship's service diesel
generator engine (No. 2) is air started; the starboard ship's service diesel generator engine (No. 1) is
electrically started. Engine control and monitoring are provided from the engine room soncole and at the
individual engine control panel.
b.
Ship's Service Generator Two 250kW brushless exciter generators provide 240 Vac, three-phase,
.
60 Hz primary ship's service power. The output leads on the generator are in the low "Y" configuration, (see
FIGURE 1-29A). A center ground lead is not used. Each generator is capable of providing 110 percent of the
necessary at sea load for the propulsion and safety of the ship under normal conditions. The generators may
be operated in parallel; however, normal operation has one generator on line and the other in reserve.
c.
Main Switchboard The main switchboard (FIGURE 1-30), located in the engine room operating
.
station, provides generator selection, shore power selection, and power distribution for ship's service 240 Vac
and 120 Vac power. Distribution of 120 Vac is accomplished by ship's service 120 Vac isolation transformer
located in the engine room operation station. The emergency switchboard bus tie provides 240 Vac to the
emergency switchboard. Power selection is provided by closing circuit breakers on the switchboard. Power
monitoring is provided by ammeters, voltmeters, frequency meters, and synchronization meters. Controls are
provided for manual and automatic generator voltage regulation and generator engine speed regulation. The
switchboard bus tie also serves as an emergency 240 Vac power feedback source for the main switchboard
from the emergency switchboard, to power selected equipment systems during emergency power conditions.
An interlock system is incorporated into the switchboard to prevent shore power from being applied to the
switchboard while generator power is applied. The interlock system also prevents the emergency switchboard
emergency generator circuit breaker from being closed.
d.
Emergency Switchboard The emergency switchboard (FIGURE 1-31), located in the emergency
.
generator room, normally receives 240 Vac primary power from the main
Change 3
|
||
|
||
