Rice Lake Weigh Modules/Mount Assemblies - Manual (Page 80)

GLOSSARY
G-4
I
INFLUENCE FACTORS
Environmental elements that may alter or
interrupt an electronic or mechanical
indication (e.g., temperature, humidity, radio
frequency interference, barometric pressure,
electric power).
INTERFACE
A device or circuit that allows two units to
communicate. Some of the standard interfaces
used in the scale industry are 20 mA current
loop, BCD, RS-232, RS-422 and RS-485.
INTRINSICALLY SAFE CIRCUIT
A circuit in which any spark or thermal effect is
incapable of causing ignition of a mixture of
flammable or combustible material in air under
prescribed test conditions in its most easily
ignitable concentration.
INTRINSICALLY SAFE SYSTEM
An assembly of interconnected intrinsically safe
apparatus, associated apparatus and intercon-
necting cables in which the parts of the system,
which may be used in hazardous (classified)
locations, are intrinsically safe circuits; may
include more than one intrinsically safe circuit.
INTRINSIC SAFETY BARRIER
A network designed to limit the energy (voltage
and current) available to the protected circuit
in the hazardous (classified) location under
specified fault conditions.
INTRINSIC SAFETY GROUND BUS
A grounding system that has a dedicated
conductor, separate from the power system, so
ground currents will not normally flow, and
which is reliably connected to a ground
electrode in accordance with Article 200 of the
NEC.
INSULATION RESISTANCE
The DC resistance measured between the load
cell circuit and the load cell structure; normally
measured at fifty volts DC and under standard
test conditions.
INTERNATIONAL PROTECTION (IP)
RATING
A rating system that defines a product’s or
enclosure’s protection against the ingress of
solid objects and liquids. See page 257 for a
chart defining the IP rating system.
I/O (Input/Output)
The circuits or devices that allow a digital unit
to send (output) data and receive (input) data.
J
J-BOX (Junction Box)
A box or enclosure used to join different runs of
cable or wiring; it contains space and terminals
for connecting and branching the enclosed
conductors and adjustments to provide load cell
trimming.
L
LATCH
To maintain a closed (energized) state in a pair
of relay contacts after initial energization from
a single electrical pulse.
LATCHING RELAY
A relay which locks into the mode for which it
is energized (On or Off); requires a start-stop
button; once activated it stays activated until
the setpoint is reached or the stop button is
pushed.
LED (Light Emitting Diode)
A semiconductor light source that emits visible
light or invisible infrared radiation.
LEVER
A tool that transfers force equally with
reduction or multiplication.
LIVE LOAD
The load applied to a scale base that is actually
being measured by the weighing system.
LOAD
The weight or force applied to the load cell.
LOAD CELL
A device which produces an output signal
proportional to the applied weight or force.
Types of load cells include beam, S-beam,
platform, compression and tension.
LOW PASS FILTER
A filter which passes frequency components
below a designated frequency and rejecting
components above that frequency.
M
MASS
The quantity of matter in a body.
MEGOHMMETER
A special ohmmeter for measuring resistances
in the megohm (10
6 ohms) range; also called a
megger.
METAL FILM RESISTOR
A fixed or variable resistor in which the
resistance element is a thin or thick film of a
metal alloy deposited on a substrate made of
plastic or ceramic material.
MICRO
A prefix meaning millionths (10
-6 ); symbol is
“ µ ”.
MICROVOLTS PER GRADUATION
The number of microvolts of live load signal
that are needed to change the display.
MINIMUM DEAD LOAD-Load Cells
Minimum dead load is specified for NTEP load
cells. In a given application, the dead load
applied to each cell must be greater than or
equal to the minimum dead load specified by
the load cell manufacturer.
MOTION DETECTION
A circuit used in an indicator to sense when the
displayed weight data is changing at a greater
rate than preset limits (or is unstable) and to
inhibit certain functions during this time.
Functions inhibited may be data output, entry
of a push-button auto zero, entry of an auto
tare value or activation of zero tracking.
MOV (Metal Oxide Varistor)
A voltage-dependent resistor whose resistance
predictably changes with voltage applied; used
in transient protectors as a shunt protection
device.
N
n
max
(Maximum Number of Scale
Divisions)
The maximum number of scale divisions for
which a product has been approved. The n
max
must be greater than or equal to the number of
divisions for which the scale will be configured.
NEGATIVE LOGIC
Binary logic in which a high negative state
represents a “1” condition and a low negative
state represents a “0” state.
NEMA
National Electrical Manufacturers Association.
NCWM (National Conference on
Weights and Measures)
An association of state and local officials.
Federal and industry representatives that adopt
uniform (model) laws and regulations (e.g.,
NIST Handbook 44).
NIST (National Institute for Standards
and Technology)
An agency of the federal government to which
all precision measurements are traceable.
Formerly the National Bureau of Standards
(NBS)
NOMINAL LOAD CAPACITY
The designed normal maximum load cell
capacity. Output load cell sensitivity is based on
this capacity unless otherwise specified.