Electrical Distribution Monitoring and Control
from the EPCC is enabled only when the operator
extinguishes the LOCAL CONTROL alarm light for a
An electrical switchboard has both analog and
switchboard.
discrete sensing devices for monitoring generator or bus
EPCC operation of circuit breakers is accomplished
output and circuit breaker status. Alarm, status, and
through the same circuits used by the switchboard
control information flows between the switchboard and
controls. Depressing an EPCC push-button indicator
the EPCC. The EPCC receives this information in one
allows the operator to energize a 28-volt dc close or trip
of three ways:
relay at the associated switchboard. The 10-position
1. Directly from potential transformers and current
synchronization CIRCUIT BREAKERS select switch
transformers
and SYNC MONITOR BYPASS push button enable
operation of the close circuit. When a relay is energized,
2. Directly from circuit breakers
a control circuit in the breaker assembly energizes a
3. Discrete inputs from switchboard relay logic
close or open trip coil to execute the desired status
circuits
change.
The voltage and current signals from the current and
Gas Turbine Control
potential transformers are sent to transducers in the
EPCC to generate voltage, current, frequency, and
The gas turbine controls available at the EPCC
power signals. These signals directly drive the power
consist of gas turbine start air selection, governor
generation and distribution system output LED meters.
mode selection, and manual bleed air valve control.
These signals are also sent to the computer for alarm
Also available at EPCC are gas turbine start and stop
generation and the PDU's demand display. The operator
control and gas turbine frequency control. These
can select the voltage displayed on the system output
operator interfaces provide discrete inputs to the
panel meter by positioning the associated SOURCE
selector switch.
LOCOP, which operates all SSGTG support systems
and gas turbine control elements.
The electrical distribution system can be operated
manually from either the switchboard or the EPCC.
The availability of an SSGTG start from the
Automatic sequencing takes place in the switchboards
EPCC is a function of the LOCOP 301 sequencer
ready to start discrete output, LOCOP LOCAL/
only when a fault condition exists. The EPCC does not
REMOTE switch, and switchboard voltage regulator
automatically control any circuit breakers as a part of
the standby generator start or any other function. The
mode switch. When the LOCOP is in REMOTE, an
operator at either the switchboard or the EPCC can
switchboard relay logic and the LOCOP sequencer
start the SSGTG. When the switchboard GTG START
generator breaker trip command are the only automatic
TRANSFER switch is in LOCAL, operators at both
breaker controls.
the switchboard and the EPCC can start the SSGTG.
Shore power breaker control from the EPCC is
When the switchboard GTG START TRANSFER
limited to the operator's sending a trip command to each
switch is in REMOTE, an operator only at the EPCC
breaker simultaneously by depressing the ALL CB
can start the SSGTG.
OPEN push button. All shore power close control and
The manual SSGTG start controls at the EPCC are
phase monitoring devices are locally operated from
switchboard No. 2 in MER No. 2. When the shore power
the ON, HIGH PRESS, and BLEED push buttons. When
breakers are closed, circuits in each switchboard will
the operator depresses the ON pushbutton, the signal is
automatically command each sSGTG governor to
combined with the HIGH PRESS or BLEED indication
DROOP to prepare for a shift from ship's power to shore
signal in the output multiplexer hardware. The start air
power.
push buttons provide only a hardware logic signal within
the EPCC and do not cause the start air piping valves to
realign. Depending upon which start air indicator is
Circuit Breaker Operation and Control
illuminated, the EPCC will send a high-pressure start or
bleed air start signal to the LOCOP.
The EPCC provides centralized control and
monitoring of 3 generator circuit breakers, 6 bus tie
An SSGTG stop is always available from its
breakers, and 12 shore power breakers. The push-button
LOCOP, its associated switchboard, and the EPCC.
indicators for these circuit breakers are located on the
Depressing the EPCC OFF push-button switch sends a
EPCC mimic panel. Control of these circuit breakers
signal to the LOCOP, which initiates a normal SSGTG
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