Appendix I Glossary - Cont'd -141210122

SERVO AMPLIFIER Either ac or dc amplifiers used

POWER SUPPLY A module that converts the

in servo systems to build up signal strength. These

115-volt 60-hertz incoming power to ac or dc power

amplifiers usually have relatively flat gain versus

at a more suitable voltage level.

frequency response, minimum phase shift, low

PRINTED CIRCUIT BOARD Devices usually

output impedance, and low noise level.

plugged into receptacles that are mounted in

modules.

SERVO SYSTEM An ac or dc motor used in servo

systems to move a load to a desired position or at a

PRIORITY Order established by relative importance

desired speed. The ac motor is usually used to drive

of the function.

light loads at a constant speed, while the dc motor

PROTECTIVE FEATURE Feature of a component

is used to drive heavy loads at varying speeds.

or component part designed to protect a component

SET POINT Numerical value of a parameter at which

or system from damage.

an alarm is actuated.

RECEIVER (1) The object that responds to the wave

SIGNAL A general term used to describe any ac or dc

or disturbance. Same as DETECTOR. (2) Equip-

of interest in a circuit; for example, input signal.

ment that converts electromagnetic energy into a

visible or an audible form. (3) In radar, a unit that

SILICON CONTROLLED RECTIFIER PACK-

converts rf echoes to video and/or audio signals.

AGE A device that furnishes controlled dc power

to a device.

REFERENCE POINT A point in a circuit to which all

other points in the circuit are compared.

SINE WAVE (1) The curve traced by the projection on

a uniform time scale of the end of a rotating arm, or

REFERENCE SIGNAL Command signal that

vector. Also known as a sinusoidal wave. (2) The

requests a specific final condition.

basic synchronous alternating waveform for all

RELAY An electromagnetic device with one or more

complex waveforms.

sets of contacts that change position by the magnetic

SOLID STATE Class of electronics components, such

attraction of a coil to an armature.

as transistors, diodes, integrated circuits, silicon

ROTOR The rotating member of a synchro that

controlled rectifiers, and so forth.

consists of one or more coils of wire wound on a

laminated core. Depending on the type of synchro,

SPAN Distance between two points.

the rotor functions similar to the primary or

SPECIAL FUNCTION Unique service performed by

secondary winding of a transformer.

a system; usually above and beyond the direct

SCALING Applying a factor of proportionality to data

designed intent of the system.

or signal levels.

STANDARD PRINT Standard drawing, schematic, or

SCAT CODE The subcategory (SCAT) code assigned

blueprint produced in the applicable technical

to the equipment, if applicable.

manual or other official technical publication.

SEB NUMBER The number of the support equipment

STATOR The stationary member of a synchro that

change that contains the modification implemented

consists of a cylindrical structure of slotted

on the corresponding equipment by the related

laminations on which three Y-connected coils are

calibration activity (laboratory).

wound with their axes 120 apart. Depending on the

type of synchro, the stator's functions are similar to

SELSYN Self-synchronizing device or synchromotor.

the primary or secondary windings of a transformer.

SENSING POINT Physical and/or functional point in

STATUS LOG Record of the instantaneous values of

a system at which a signal may be detected or

important conditions having analog values.

monitored in an automatic operation.

SUBASSEMBLY Consists of two or more parts that

SENSOR A device that is sensitive to temperature,

form a portion of an assembly or a unit.

pressure, position, level, or speed.

SWITCH (1) A device used to connect, disconnect, or

SERVICING LABEL (SL) A label attached to the

change the connections in an electrical circuit. (2)

equipment to indicate the status of the equipment

A device used to open or close a circuit.

after servicing.

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