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
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
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.