initiates a start by selecting the type of air (HP or LP) to
sensors at the GTGS are the high vibration alarm and
the high turbine inlet temperature (TIT) alarm. The high
be used and depressing the START push button.
vibration alarm is generated by an alarm detector in
The EPCC STOP pushbutton is not affected by the
S/CE No. 1. The high TIT alarm is initiated by a TIT
control transfer switches. When depressed, a signal is
high relay in the gas turbine generator control panel. In
sent to the turbine stop relay at the switchboard. The stop
addition to the alarm lights, there are status lights at the
EPCC for each GTGS.
to initiate a normal stop.
Frequency of each GTGS is controlled by an
Electrical Distribution System Monitoring
electronic governor. The electronic governor senses the
frequency of the permanent magnet alternator (PMA)
The generator status panel at the EPCC provides
and sends signals to a hydraulic actuator on the gas
meter displays and alarms for monitoring the output of
turbine. The actuator adjusts the fuel flow in the engine
the GTGSs. An additional section of this panel is for
to maintain engine speed. Frequency adjustment is made
shore power monitoring. The electrical distribution
at the EPCC by raising or lowering a motor-driven
system provides monitoring by using meter displays and
p o t e n t i o m e t e r . There are two modes of governor
alarm lights. The operator can test the conditions of
operation: NORMAL and DROOP. The NORMAL
shore power by using the phase sequence meter and its
m o d e is isochronous or constant frequency. The
associated switch.
DROOP mode is an alternate mode where frequency
decreases with increasing load.
Circuit Breaker Control
Generator Control
The EPCC provides centralized control and
monitoring of the generator circuit breakers, bus tie
Control of generator field excitation for a GTGS is
accomplished by its voltage regulator. There are two
breakers, and load center breakers. The push-button
indicators used to operate these breakers are located on
modes of voltage regulator operation available at EPCC:
the EPCC mimic panel. Control of circuit breakers from
AUTO and MANUAL. In the AUTO mode, the voltage
the EPCC is enabled only when the generator control
regulator regulates the generator output voltage to a
level set by a motor-driven reference potentiometer. In
switches at the switchboards are in the REMOTE
position.
t h e MANUAL mode, excitation current from the
voltage regulator is set by a motor-driven rheostat
Circuit breaker control at the EPCC can be divided
located at the switchboard. Voltage adjustment is made
i n t o two categories: operator initiated and logic
at the EPCC by commanding either the reference
initiated. Operator initiated circuit breaker control is
potentiometer motor (AUTO mode) or the manual
provided at the mimic panel with the push-button switch
rheostat motor (MANUAL mode) in the RAISE or
indicators. Logic initiated circuit breaker "Close"
LOWER direction. There are two modes for the voltage
commands originate when the EPCC is in the automatic
regulator: NORMAL and DROOP.
operating mode. Bus tie breakers 3S-1S and 3S-2S are
the only breakers with "Auto Trip" commands. The
System Configurations
c o m m a n d s isolate switchboard No. 3 if all three
generators are in parallel for more than 2 minutes.
The electrical system is designed so two generators
can supply all electrical loads. The third GTGS can be
Gas Turbine Control
put on standby and then automatically started and
synchronized to the bus on failure of one or both of the
Gas turbine control available at the EPCC consists
on-line generators. Automatic failure detection and
of gas turbine start and stop control and gas turbine
recovery is available only when the EPCC is in control
frequency control.
and in automatic mode, and the electric plant is in a
standard parallel or standard split-plant configuration.
M a n u a l GTGS control available at the EPCC
consists of a START push button, a STOP push button,
STANDARD SPLIT-PLANT CONFIGURA-
and a HP AIR/LP AIR GTRB start mode selector switch.
TIONS.-- Standard split-plant operation requires two
The start controls are enabled only when the control
on-line generators, but not paralleled. The switchboard
transfer switch at the generator control panel and
bus of the off-line generator is energized through the bus
switchboard are in the REMOTE position. The operator
tie connection to one of the on-line switchboards. The
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