Appendix I Glossary - Cont'd -141210120

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.

taken.

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

load.

component part.

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

digits.

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

units.

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

second.

are accessible.

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