through normally closed contacts; it may gate a
The command signal is developed by an
operator at a throttle. When it reaches the PLA
fixed voltage, through normally open contacts,
to drive the PLA actuator to idle if one of the
electronics, it first goes through a command rate
conditions discussed previously exists.
limiting circuit. This circuit does not let the
The limiting functions of the PLA actuator
command signal (into summation amplifier No.
1) exceed a rate of change of 2.1 volts
electronics have a passive role during normal
operation of the PT. Only when a limit is exceeded
(22.5)/second increasing or 9.0 volts
or, as in the case of speed limiting, seems like it
(89)/second decreasing. At summation amplifier
is going to be exceeded, do the limiting circuits
No. 1, the command signal is compared to the
become active.
position feedback signal. The difference is called
the position error signal.
The inputs to the limiting circuits are PT speed
and PT torque. The speed signal comes from one
The position error signal is passed through the
controlled limited attenuator. Here the signal is
of two PT speed transducers through a signal
conditioning circuit. The torque signal is
passed unchanged or is attenuated (decreased in
calculated by the torque computer in the FSEE.
amplitude). Whether attenuation occurs or not
depends on the limit discrete signal. This signal
If more than one event (overspeed or over-
torque) occurs simultaneously, the analog signals
is generated from within the limit loops when the
from the speed acceleration and torque limiting
torque or speed limit is exceeded. The attenuator
circuits are brought to the same point. At this
attenuates the position error signal when the limit
point, the largest of the signals gates to
discrete signal is present. The attenuation of the
position error signal lowers its effect on the PLA
summation point No. 2 in the control loops. The
analog signal from the rate limit can be applied
actuator.
to summation point No. 2 regardless of other
inputs.
NOTE: When the torque or speed limits are
The operation of the control circuits in the
exceeded, the limit discrete and the analog limiting
PLA actuator electronics can be altered by the
signals are simultaneously generated. The limit
battle override function. During testing and
discrete signal lets the analog signal have more
emergency operation of the ship, authorized
effect by diminishing the drive signal before
personnel can activate this function at the
the analog limiting signal is added to it at
control consoles. In the battle override mode, the
summation point No. 2.
fail-to-idle relay will not operate. This will
prevent the PLA being forced to idle. The analog
The position error signal out of the attenuator,
limit signal used by the limit loops to lower PLA
the speed (PLA actuator rate) feedback, and the
actuator position is inhibited. ( NOTE: Depressing
analog limiting signal from the limit loops is added
the engine synchronizing switch located within the
into summation point No. 2. There they are
FSEE will activate battle override as long as the
algebraically summed to generate the unamplified
switch is depressed.)
drive signal for the servomotor. The tachometer
feedback signal lowers the drive signal whenever
FSEE CIRCUITRY TESTS
the PLA actuator moves fast. When the PLA
actuator is moving slowly, the tachometer
The electronics within the FSEE covers various
feedback is low and its effect is minimal on the
internal tests to check if circuits are working
drive signal.
properly. The tests are for the torque computer,
The analog limiting signal is generated in the
the speed limit circuit, and the overspeed switch.
limiting electronics when the torque, speed,
These tests only test the FSEE circuitry. For a total
acceleration, or PLA actuator rate limit is
system test, refer to the applicable maintenance
reached. This signal is proportional to the amount
requirement card (MRC) of the Planned
of PT torque, speed, acceleration, or PLA
Maintenance System (PMS).
actuator rate present over their respective limit.
It drives the MFC in the direction necessary to
Torque computer test. On this test, the
remove the PT from the limit condition.
torque computer uses several fixed parameter
The corrected drive signal is sent through a
values to calculate a torque value. If the value
power amplifier where it is amplified by a gain
exceeds the reference set point, an indicator light
of 20. The signal then goes through the fail-to-
on the control console signals that the torque test
idle relay to the servomotor. The fail-to-idle relay
passed.
connects the drive signal to the PLA actuator
2-56
