ROTARY SWITCH-- A multicontact switch with
PROTECTIVE FEATURE-- The feature of a
component or component part designed to protect
contacts arranged in a circular or semicircular
a component or system from damage.
PROTECTIVE POTENTIAL-- A term used in
RUSTING-- Corrosion of iron or iron-base alloy to
cathodic protection to define the minimum
form a reddish-brown product known as rust, which
potential required to mitigate or suppress corrosion.
is primarily hydrated iron oxide. A term properly
For steel in quiescent seawater, a value of -0.80 volt
applied only to ferrous alloys.
to Ag/AgCl reference electrode is generally used.
SCALING-- Applying a factor of proportionality to
RECIPROCAL-- The value obtained by dividing the
data or signal levels.
number 1 by any quantity.
SCHEMATIC CIRCUIT DIAGRAM-- A circuit
RECTIFIER-- A device used to convert ac to
diagram in which component parts are represented
by simple, easily drawn symbols. May be called
REFERENCE ELECTRODE-- A half-cell of
reproducible potential by means of which an
unknown electrode potential can be determined on
SCHEMATIC SYMBOLS-- A letter, abbreviation, or
some arbitrary scale (for example, Ag/AgCl, SCE,
design used to represent specific characteristics or
Cu/CuSO4). A standard against which the
components on a schematic diagram.
potentials of other metal and nonmetallic conductor
SECONDARY-- The output coil of a transformer.
electrodes are measured and compared.
REFERENCE POINT-- A point in a circuit to which
SELF-INDUCTANCE-- The production of a counter
all other points in the circuit are compared.
electromotive force in a conductor when its own
magnetic field collapses or expands with a change
REFERENCE SIGNAL-- The command signal that
in current in the conductor.
requests a specific final condition.
RELAY-- An electromagnetic device with one or more
SELSYN-- Self-synchronizing device or synchro-
sets of contacts that changes contact position by the
magnetic attraction of a coil to an armature.
SENSING POINT-- A physical and/or functional
RELUCTANCE-- A measure of the opposition that a
point in a system at which a signal maybe detected
material offers to magnetic lines of force.
or monitored in an automatic operation.
REPULSION-- The mechanical force tending to
SENSITIVITY-- (1) For an ammeter, the amount of
separate bodies having like electrical charges or like
current that will cause full-scale deflection of the
meter. (2) For a voltmeter, the ratio of the voltmeter
RESIDUAL MAGNETISM-- Magnetism remaining
resistance divided by the full-scale reading of the
in a substance after removal of the magnetizing
meter, expressed in ohms-per-volt.
SENSOR-- A device that is sensitive to temperature,
RETENTIVITY-- The ability of a material to retain its
pressure, position, level, or speed.
RHEOSTAT-- (1) A resistor whose value can be
SERIES CIRCUIT-- An arrangement where electrical
varied. (2) A variable resistor that is used for the
devices are connected so that the total current must
purpose of adjusting the current in a circuit.
flow through all the devices; electrons have one
path to travel from the negative terminal to the
RLC CIRCUIT-- An electrical circuit that has the
SERIES-PARALLEL CIRCUIT-- A circuit that
ROOT MEAN SQUARE (RMS)-- The equivalent
consists of both series and parallel networks.
heating value of an alternating current or voltage,
SET POINT-- The numerical value of a parameter at
as compared to a direct current or voltage. It is 0.707
which an alarm is actuated.
times the peak value of a sine wave.