Cut Sheet

Volume 8—Sensing Solutions CA08100010E—November 2012 www.eaton.com V8-A2-7
Appendix 2
Glossary of Terms
Sensing Distance—The
physically measured distance
from a particular sensor to a
particular target. The three
specific definitions of sensing
distance are:
Effective Sensing
Distance (Sr)—The
operating range of a sensor
measured at nominal
voltage and temperature.
Nominal Sensing Distance
(Sn)—The distance at
which a sensor is designed
to detect a standard target
at rated voltage and
temperature.
Usable Sensing Distance
(Su)—The distance at
which a particular sensor
should sense a standard
target over the operating
temperature and voltage
limits recommended by the
manufacturer.
Sensing Range—See
Sensing Distance.
Shielded—An inductive style
that allows the user to mount
the sensor flush in metal up
to the sensor face without
the sensor detecting the
presence of that metal.
Short Circuit Protection—
Internal circuitry that protects
the sensor from electrical
damage due to excessive
current from a wiring short
circuit.
Sleet-Proof Enclosure—So
constructed or protected that
the accumulation of sleet (ice)
under specified test
conditions will not interfere
with the successful operation
of the apparatus including
external operation
mechanism(s).
Slow Break Contacts—
Contacts for which the speed
of the contact make/break is
dependent upon the speed of
the operator.
Snap Action Contacts—
Contacts for which the speed
of the contact make/break is
independent of the operator
speed. Different tripping and
reset points occur in each
direction (differential travel).
Snubber Circuit—Circuit
composed of a resistor and a
capacitor in series, and
connected across the device.
This circuit serves to protect
a sensor against electrical
transients.
Source—See Thru-Beam
Source.
Standard Target—A metallic
object used for sensing
distance measurement with
inductive proximity sensors.
For similar sensor models the
standard target is a square
mild steel plate 1 mm thick.
The length of each side is
equal to the diameter of the
sensing face.
Submersible Enclosure—So
constructed as to prevent
water ingress when
submerged in water under
specified test conditions of
pressure and time.
Thru-Beam Detector—The
component of a thru-beam
sensing system that receives
the light being emitted by the
source.
Thru-Beam Sensing—A
sensing mode
where the light
source and detector are
di
rected at each other across
an area in which a target
passes. Detection occurs
when the target blocks the
light beam travelling directly
between the source and
detector (called the “effective
beam”).
Thru-Beam Source—The
component of a thru-beam
sensing system that emits
light.
Time Delay Before
Availability—Time delay
from when power is initially
supplied to a solid-state
sensor device and the time
when it will be ready to
detect a target.
Total Travel (T.T.)—The
sum of the pretravel and total
overtravel expressed by
distance or angle.
Translucent—A translucent
object allows some reduced
level of light to pass through
it. Translucent objects can
result in reliability problems in
sensing if the contrast
between light beam blocked
and unblocked conditions is
too low. See also Contrast
and Opaque.
UL
®
—Underwriters
Laboratories, Inc., United
States. Independent facility
which tests and certifies
electrical equipment.
Unshielded—An inductive
style that requires a metal-
free zone surrounding the
sensor face when mounting.
Range for this type is typically
1.5–2 times the shielded
range.
VDE—Verband Deutscher
Electro-techniker, Federal
Republic of Germany.
Watertight Enclosure—So
constructed as to prevent
water ingress applied in the
form of a hose stream under
specified test conditions.
Wavelength—Distance
traveled by light while
completing one complete
sine-wave expressed in
nanometers (nm). Each color
has a specific wavelength.
Zero Crossing—The point in
an AC cycle when the sine
wave is at zero.