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Page Title: Compensation Signals - Cont'd
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the shaft of the linear synchro to provide a visual
acceleration signal being fed to the meridian control
indication of own ship's speed.
integrator cutout, which operates a relay, cutting out the
tilt signal during excessive accelerations.
The own ship's speed signal is applied to the input
For the tilt signal outputs from the electrolytic
stage of a type 1 computer amplifier in the speed
component computer. The speed computer (fig. 4-28)
bubble level to average out to zero, the compass must
contains two type 1 computer amplifiers, a speed
be in perfect balance, and all compensating signals
resolver and dial (B4), a synchro control transformer
computed exactly. The constant torque compensation
(B5), and a motor tachometer (B6).
system will then compensate, within limits for errors in
computation of other compensating signals.
The motor-tachometer (B6) is a 400-Hz servomotor
tachometer generator built into the same housing. The
The constant torque compensation system for the
motor is a 2-phase, 4-pole, induction motor with a fixed
slave gyro is identical to the meridian gyro system.
field and a control field. The tachometer generator
section consists of a 2-phase, 2-pole stator and a copper
Operation of Compensation Circuits
shell rotor. One stator field (F1) is excited from the
The own ship's speed repeater operates on 60-Hz
115-volt, 400-Hz supply. The other stator field (F2) is
data obtained from the ship's underwater log transmitter.
not excited as long as the rotor is stationary (the axes of
The output of the repeater, however, is 400-Hz data. The
the two stator windings are 90 apart). When the shaft
repeater contains a 60-Hz servomotor (B1), a 60-Hz
of the rotor is turned, a voltage is induced in the rotor
synchro control transformer (B2), a 400-Hz linear
and rotor current flow is proportional to rotor speed.
synchro and dial (B3), and a type 2 computer amplifier
This rotor current produces a magnetomotive force
(A1). (See figs. 4-27 and 4-28.)
proportional to rotor current. This magnetomotive force
is combined with the magnetomotive force of the refer-
The linear synchro is an induction device like other
ence winding to produce a resultant field, the axis of
synchros, but differs from other types in that it has one
which is displaced in the direction of rotation of the rotor
input rotor winding and one center-tapped output stator
cup. The angle between the resultant field axis and the
winding that produces an output voltage that is a linear
axis of the output winding varies with the speed. Hence,
function of its rotor position. The rotor winding is
the coupling between the two stator windings varies
excited from the 400-Hz supply. When the rotor is in
with speed. Thus, the output voltage varies with the
such a position that the axes of the two windings are
speed. Its frequency is 400 Hz, the same as that of the
separated by 90 electrical degrees, no voltage is induced
reference field, and the phase of the output voltage is
in the output stator winding. If the rotor is displaced in
dependent upon the direction of rotation of the rotor cup.
one direction from this zero voltage position, a voltage
is induced in the output winding that is proportional to
The own ship's speed signal is amplified and fed to
the amount of rotor displacement. If the rotor is
the rotor winding of the speed resolver (B4). Heading
displaced in the opposite direction, a voltage of opposite
data from the master compass is applied to the input of
phase is induced in the output winding that is also
the control transformer (B5), and the output of the
proportional to the amount of rotor displacement.
control transformer (B5) in series with a damping
voltage obtained from the generator section of the
The 60-Hz servomotor is a 2-phase, 2-pole,
motor-tachometer (B6) is fed to the input of the second
induction motor, with a fixed field excited from the
type 1 computer amplifier. The damping signal voltage
60-Hz power line, and a control field connected to the
from the motor-tachometer is used to stabilize the com-
type 2 computer amplifier output.
puter servoloop and to introduce a small time lag in the
computer. his time lag is required since the direction
The input to the repeater is the own ship's speed
of motion of the ship's center of gravity differs from the
from the underwater log to the control transformer (B2)
ship's heading for a short interval after starting a course
(fig. 4-28). The output signal voltage from the control
change. In other words, when rudder is first applied to
transformer, representing ship's speed, is fed to the input
turn the ship, the ship slides sidewise to some extent so
of the type 2 computer amplifier. The servomotor (B1)
that the original course is maintained for a short interval
drives the control transformer rotor to its null position,
even though the ship's heading has changed.
and at the same time positions the linear synchro rotor
The output of the second type 1 computer amplifier
(B3) to a position corresponding to the ship's speed. The
linear synchro output, then, is a 400-Hz voltage
excites the control field of the motor section of the
proportional to own ship's speed. A dial is attached to
motor-tachometer (B6), which drives the tachometer

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