EMERGENCY An event or series of events in
CONVERTER A device for changing one type of
progress that will cause damage to equipment unless
signal to another; for example, alternating current
immediate, timely, and correct procedural steps are
to direct current.
CORRECTIVE MAINTENANCE Includes location
ERROR DETECTOR The component in a servo
and repair of equipment failures.
system that determines when the load has deviated
CORRESPONDENCE The term given to the posi-
from its ordered position, velocity, and so on.
tions of the rotors of a synchro receiver when both
ERROR SIGNAL (1) In servo systems, the signal
rotors are on 0 degree or displaced from 0 degree by
whose amplitude and polarity or phase are used to
the same angle.
correct the alignment between the controlling and
DAMPING (1) The process of smoothing out
the controlled elements. (2) The name given to the
oscillations. (2) In a meter, this process is used to
electrical output of a control transformer.
keep the pointer of the meter from overshooting the
EXCITATION VOLTAGE The supply voltage
correct reading. (3) A mechanical or electrical
required to activate a circuit.
technique used in synchro receivers to prevent the
rotor from oscillating or spinning. Damping is also
FAIL Loss of control signal or power to a component.
used in servo systems to minimize overshoot of the
Also breakage or breakdown of a component or
DATA TRANSMISSION The transfer of information
FAIL POSITION Operating or physical position to
from one place to another or from one part of a
which a device will go upon loss of its control signal.
system to another.
FEEDBACK A value derived from a controlled
DEAD BAND The range of values over which a
function and returned to the controlling function.
measured variable can change without affecting the
FREQUENCY (1) The number of complete cycles per
output of an amplifier or automatic control system.
second existing in any form of wave motion, such
DEMAND To request a log printout or data display.
as the numbers of cycles per second of an alternating
current. (2) The rate at which the vector that
DEMODULATOR A circuit used in servosystems to
generates a sine wave rotates.
convert an ac signal to a dc signal. The magnitude
of the dc output is determined by the magnitude of
FUNCTION To perform the normal or characteristic
the ac input signal, and its polarity is determined by
action of something, or a special duty or
whether the ac input signal is in or out of phase with
performance required of a person or thing in the
the ac reference voltage.
course of work.
DIGITAL Pertaining to data in the form of digits.
GATE As applied to logic circuitry, one of several
types of electronic devices that will provide a
DIGITAL CLOCK A device for displaying time in
particular output when specified input conditions
are satisfied. Also, a circuit in which a signal
DIRECT CURRENT An electric current that flows in
switches another signal on or off.
one direction only.
GENERATOR A machine that converts mechanical
DRIFT A slow change in some characteristics of a
energy to electrical energy by applying the principle
device, such as frequency, current, and direction.
of magnetic induction. A machine that produces ac
ELECTRICAL ZERO A standard synchro position,
or dc voltage, depending on the original design.
with a definite set of stator voltages, that is used as
GYRO Abbreviation for gyroscope.
the reference point for alignment of all synchro
GYROSCOPE A mechanical device containing a
spinning mass mounted so it can assume any
ELECTRICAL-LOCK A synchro zeroing method.
position in space.
This method is used only when the rotors of the
HERTZ A unit of frequency equal to one cycle per
synchros to be zeroed are free to turn and their leads