12,780 RPM SPEED CHANNEL--Provides
The LOCOP (fig. 3-34, view A) is a cabinet
mounted on the generator end of the module. On
the following functions:
the outside of the cabinet doors are the controls
Inhibits the start temperature limit valve
and indicators for local GTGS operation. Inside
control circuit to permit TIT to increase
the cabinet (view B) are the electronic components
above 1525F.
of the system. Among these components are
printed circuit cards, voltage regulators, a 12
I n h i b i t s the start overtemperature
volt dc converter module, a relay assembly, and
shutdown circuit to permit TIT to increase
a temperature and speed control unit. The control
elements of the system are powered by 28 volts
above 1600F.
dc from the SWBD. The SWBD 28-volt dc supply
has a bank of 15 amp-hr lead-calcium batteries
Arms the engine underspeed alarm circuit
to enable an alarm to sound if the speed
for backup. This battery bank allows starting of
drops below 12,780 rpm after being at
a GTGS when the ship is without 450-volt ac
12,780 rpm for more than 2 seconds.
power.
The model 139 LOCOP is a computer
15,800 RPM SPEED CHANNEL--Provides
controlled digital system. It uses a central
engine overspeed protection. If engine speed
microprocessor to control and monitor the GTGS.
The LOCOP has the necessary power supplies to
exceeds 15,800 rpm, an automatic shutdown is
initiated.
power all logic and switching level voltages.
The LOCOP system power supply printed
600F TEMPERATURE CHANNEL--
circuit card and associated heat sink are mounted
Provides automatic shutdown if 600F TIT is not
on the left side of the LOCOP cabinet. The power
reached within 10 seconds after reaching 2200
supply has the following components:
rpm. It also de-activates the fail-to-fire circuit
when 600F TIT is obtained.
1. A dc-dc converter that supplies 5 volts
dc and 15 volts dc
1500F TEMPERATURE CHANNEL--
2. A switching power supply that supplies
Activates the start temperature limit valve control
12 volts dc and 10 volts dc
3. A switching power supply that supplies 5
circuit if 1500F TIT is reached before the turbine
reaches 12,780 rpm. The circuit intermittently
volts dc
energizes the start temperature limit control valve
solenoid through a pulse timer. This reduces
The audible alarm system has a printed circuit
card where six different audible signals are
acceleration fuel flow, and thereby reduces TIT
below 1500F.
electronically generated and any one of the six are
programmably selected. The selected signal is then
1600F TEMPERATURE CHANNEL--
amplified by the alarm amplifier assembly. The
Initiates an automatic shutdown if 1600F TIT
amount of amplification is adjustable to fit the
environment. The printed circuit card is mounted
is reached below 12,780 rpm.
in the card rack. The alarm amplifier assembly
1880F TEMPERATURE CHANNEL--
and speaker are mounted externally on the right
side of the LOCOP cabinet.
Causes an alarm to sound if 1880F TIT is
reached.
For general description purposes, we have
grouped the LOCOP electronics into their
1945F TEMPERATURE CHANNEL--
associated tasks.
Starts an automatic shutdown if 1945F TIT is
CPU, MEMORY, AND I/O INTERFACE--
reached above 12,780 rpm.
Comprise two microprocessors in the system
computer control. The central processing unit
MODEL 139 GTGS LOCOP
(CPU) card has the microprocessor. The memory
The model 139 LOCOP provides start/stop
card has the system control program and data
storage memory space. The I/O interface card
sequencing for the GTGS, monitoring and alarms
for critical turbine and generator parameters,
provides the link between the computer control
signal conditioning for panel meters, and
and the outside world. The LOCOP has two
transmission of selected data to the ECSS.
computer control systems for faster, more
3-49
