In the manual mode, the operator must generate the
masker air ON after a start sequence, the start air system
start or stop commands at every step of the sequence.
valves will automatically align to allow masker air to
This means the operator must make sure each step is
flow to the masker air belts. With the masker air in the
accomplished at the proper time. The sequencing of
OFF condition after a start sequence, the masker transfer
valve will remain in the start position. The operator can
these manual controls is the same as those shown in the
perform both of these valve alignments manually from
time sequential flow charts found in the EOSS and
the PACC.
appropriate technical manuals.
Prairie Air System.-- The prairie air system consists
In the manual initiate mode, the starting and
of the prairie air supply valve. At the PACC, the operator
stopping of the GTE is in a semiautomatic mode. In this
can use the ON/OFF push-button indicator to operate
mode, the engine will start up or shut down
and control prairie air in both engine rooms. If one of
automatically. The control electronics at the PLCC will
the prairie supply valves should fail to respond to a
automatically sequence the required start-up and
command, both sections of the push-button indicator
shutdown steps. This mode is semiautomatic because
will fail to illuminate.
operation of the brake and clutch (the brake only on the
CG-47 class ships) must be done manually. Now, let's
Anti-Icing Air System.-- The anti-icing air system
shift from the GTM control system and take a look at
includes a bleed air injection system and an electrical
the EOT control system.
intake heater system. For both the GTMs and GTGSs,
the bleed air injection system is used to increase the
EOT Control System
intake combustion air temperature. The electrical heater
in this system is used to prevent ice formation of the
The EOT control system controls the rpm and pitch
stack intake louvers and the blow-in doors. For the
signals for both engine rooms. This system is used when
operator at the PACC to be able to use the pushbuttons
the PACC is in control of the throttles.
to control the heaters, the intake heater controllers must
To generate propulsion command information, the
be in the ON position.
ECSS uses the three following types of EOTs:
For each GTM and GTGS, monitoring for the bleed
1. Standard orderEOTs consisting of standard
air injection system and the anti-icing system is
engine commands, such as 2/3 back, 1/3 back, stop, 1/3
available at the PACC. The operator at the PACC can
ahead, 2/3 ahead, and so forth
control the bleed air injection system manually.
2. DigitizedAn EOT system that provides rpm
High-Pressure Air System.-- The high-pressure air
commands to 0 to 200 rpm in 1-rpm increments and
system is used for emergency starting of the gas turbine
pitch commands of -50 to +100 percent in 1-percent
increments
through an HP/LP air reducing station (except on
DDG-993 class ships). It is also the primary means to
3. Plant modeEOTs consisting of commands for
start the first GTG, because bleed air is not available.
secured, split-plant, and full-power operations
These three EOT's are at the SCC and the PACC. All
the five air flasks in each MER and to the four air flasks
three communicate via the command and control serial
in the No. 3 GTG room.
data bus.
STANDARD ORDERS.-- For standard orders, the
GTM Control System
operator initiates the commands at the SCC by moving
Most of the GTM control and monitoring circuitry
the integrated throttle control (ITC) lever to the standard
is used primarily for normal start-up and shutdown of
order position and depressing the stand order ALERT
the propulsion gas turbines. All four GTM control and
push button. This sends the order to the PACC and the
monitoring functions can be accomplished at the PACC.
PLCC for that particular shaft. If the PACC has control,
At the PACC, there are three possible start/stop modes
the operator can acknowledge the order by using either
for each GTM: (1) manual, (2) manual initiate, and (3)
one of the two following procedures:
auto initiate. We will describe the auto initiate mode in
1. Pushing the STD ORDER switch indicator,
the plant mode control section of this chapter. For now,
let's take a brief look at the manual and manual initiate
which silences the EOT bell, and moving the ITC to
match the command from the bridge, as displayed by the
modes.
3-5