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APPENDIX
This document defines the terminology and
performance parameters pertaining to engineering
specifications of load cell products. The objective of
this terminology standard is to promote effective
communication of specifications and to constitute a
reference for uniformity. The definitions herein are
generally compatible with common understanding in
the load cell community and are an expansion of
those found in “Load Cell Terminology and Test
Procedure Recommendations,” Third Edition, 1985,
Scale Manufacturers Association, and in OIML
International Recommendation R60, 1991 Edition.
This document includes modifications to the
definitions in the above referenced standards to
correct some of their inconsistencies and
inadequacies.
For convenience, terms which are defined in this
standard are printed in upper case when used in the
definition of another term.
AMBIENT TEMPERATURE
The temperature of the medium surrounding the
LOAD CELL.
AXIAL LOAD
A load applied along the PRIMARY AXIS.
BAROMETRIC SENSITIVITY
The change in ZERO BALANCE due to a change in
ambient barometric pressure. Normally expressed in
units of %RO/atm.
CALIBRATION
The comparison of LOAD CELL OUTPUT against
standard test loads.
CAPACITY
The maximum AXIAL LOAD a LOAD CELL is
designed to measure within its specifications.
COMBINED ERROR
The maximum deviation of the CALIBRATION curve
from the straight line drawn between MINIMUM
LOAD OUTPUT and MAXIMUM LOAD OUTPUT,
normally expressed in units of %FS. Both ascending
and descending curves are considered.
CREEP
The change in LOAD CELL SIGNAL occurring with
time while under load and with all environmental
conditions and other variables remaining constant.
Normally expressed in units of % of applied load
over a specified time interval. It is common for
characterization to be measured with a constant load
at or near CAPACITY.
CREEP RECOVERY
The change in LOAD CELL SIGNAL occurring with
time immediately after removal of a load which had
been applied for a specified time interval,
environmental conditions and other variables
remaining constant during the loaded and unloaded
intervals. Normally expressed in units of % of
applied load over a specified time interval. Normally
the applied interval and the recovery interval are
equal. It is common for characterization to be
measured with a constant load at or near CAPACITY.
CREEP RETURN
The difference between LOAD CELL SIGNAL
immediately after removal of a load which had been
applied for a specified time interval, environmental
conditions and other variables remaining constant
during the loaded interval, and the SIGNAL before
application of the load. Normally expressed in units
of % of applied load over a specified time interval. It
is common for characterization to be measured with
a constant load at or near CAPACITY.
DEFLECTION
The displacement of the point of AXIAL LOAD
application in the PRIMARY AXIS between the MDL
and MDL+CAPACITY load conditions.
ECCENTRIC LOAD
Any load applied parallel to but not concentric with
the PRIMARY AXIS.
FULL SCALE or FS
The OUTPUT corresponding to MAXIMUM LOAD in
any specific test or application.
HYSTERESIS
The algebraic difference between OUTPUT at a given
load descending from MAXIMUM LOAD and OUTPUT
at the same load ascending from MINIMUM LOAD.
Normally expressed in units of %FS. It is common for
characterization to be measured at 40-60% FS.
Load Cell Terms & Definitions
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INPUT RESISTANCE
The resistance of the LOAD CELL circuit measured at
the excitation terminals with no load applied and
with the output terminals open-circuited.
INSULATION RESISTANCE
The DC resistance measured between the bridge
circuit and the case. Normally measured at 50 VDC.
LOAD CELL
A device which produces an OUTPUT proportional to
an applied force load.
MAXIMUM AXIAL LOAD, SAFE
The maximum AXIAL LOAD which can be applied
without producing a permanent shift in performance
characteristics beyond those specified. Normally
expressed in units of % CAPACITY.
MAXIMUM LOAD
The highest load in a specific test or application,
which may be any load up to and including CAPACITY
+ MINIMUM LOAD, but may not exceed CAPACITY
significantly.
MAXIMUM AXIAL LOAD, ULTIMATE
The maximum AXIAL LOAD which can be applied
without producing a structural failure. Normally
expressed in units of % CAPACITY.
MAXIMUM LOAD AXIS MOMENT, SAFE
The maximum moment with respect to the
PRIMARY AXIS which can be applied without
producing a permanent shift in performance
characteristics beyond those specified.
MAXIMUM MOUNTING TORQUE, SAFE
The maximum torque which can be applied
concentric with the primary axis without producing a
permanent shift in performance characteristics
beyond those specified.
MAXIMUM SIDE LOAD, SAFE
The maximum SIDE LOAD which can be applied
without producing a permanent shift in performance
characteristics beyond those specified.
MEASURING RANGE
The difference between MAXIMUM LOAD and
MINIMUM LOAD in a specific test or application. It
may not exceed CAPACITY.
MINIMUM DEAD LOAD or MDL
The smallest load for which specified performance
will be met. It is normally equal to or near NO LOAD
in single mode applications and is of necessity equal
to NO LOAD in double mode applications.
MINIMUM LOAD
The lowest load in a specific test or application,
differing from NO LOAD by the weight of fixtures and
load receptors which are attached plus any
intentional pre-load which is applied.
MODE
The direction of load. tension & compression are
each one mode.
NATURAL FREQUENCY
The frequency of free oscillations under conditions
of NO LOAD.
NO LOAD
The condition of the LOAD CELL when in its normal
physical orientation, with no force input applied, and
with no fixtures or load receptors attached.
NONLINEARITY
The algebraic difference between OUTPUT at a
specific load and the corresponding point on the
straight line drawn between MINIMUM LOAD and
MAXIMUM LOAD. Normally expressed in units of
%FS. It is common for characterization to be
measured at 40-60 %FS.
NONREPEATABILITY
The maximum difference between OUTPUT readings
for repeated loadings under identical loading and
environmental conditions. Normally expressed in
units of %RO.
OUTPUT
The algebraic difference between the SIGNAL at
applied load and the SIGNAL at MINIMUM LOAD.
OUTPUT RESISTANCE
The resistance of the LOAD CELL circuit measured at
the SIGNAL terminals with no load applied and with
the excitation terminals open-circuited.
PRIMARY AXIS
The axis along which the LOAD CELL is designed to
be loaded.
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Load Cell Terms & Definitions, Continued
RATED OUTPUT or RO
The OUTPUT corresponding to CAPACITY, equal to
the algebraic difference between the SIGNAL at
(MINIMUM LOAD + CAPACITY) and the SIGNAL at
MINIMUM LOAD.
RESOLUTION
The smallest change in load which produces a
detectable change in the SIGNAL.
SHUNT CALIBRATION
Electrical simulation of OUTPUT by connection of
shunt resistors of known values at appropriate
points in the circuitry.
SIDE LOAD
Any load at the point of AXIAL LOAD application
acting at 90˚ to the PRIMARY AXIS.
SIGNAL
The absolute level of the measurable quantity into
which a force input is converted.
SPAN
Another name for RATED OUTPUT.
STATIC ERROR BAND or SEB
The band of maximum deviations of the ascending
and descending calibration points from a best fit line
through zero OUTPUT. It includes the effects of
NONLINEARITY, HYSTERESIS, and non-return to
MINIMUM LOAD. Normally expressed in units of
%FS.
SEB OUTPUT
A computed value for OUTPUT at CAPACITY derived
from a line best fit to the actual ascending and
descending calibration points and through zero
OUTPUT.
SYMMETRY ERROR
The algebraic difference between the RATED
OUTPUT in tension and the average of the absolute
values of RATED OUTPUT in tension and RATED
OUTPUT in compression. Normally expressed in
units of %RO.
TEMPERATURE EFFECT ON OUTPUT
The change in OUTPUT due to a change in AMBIENT
TEMPERATURE. Normally expressed as the slope of
a chord spanning the COMPENSATED
TEMPERATURE RANGE and in units of %/°F or
%/100°F.
TEMPERATURE EFFECT ON ZERO
The change in ZERO BALANCE due to a change in
AMBIENT TEMPERATURE. Normally expressed as
the slope of a chord spanning the COMPENSATED
TEMPERATURE RANGE and in units of %RO/°F or
%RO/100°F.
TEMPERATURE RANGE, COMPENSATED
The range of temperature over which the LOAD CELL
is compensated to maintain OUTPUT and ZERO
BALANCE within specified limits.
TEMPERATURE RANGE, OPERATING
The extremes of AMBIENT TEMPERATURE within
which the LOAD CELL will operate without
permanent adverse change to any of its performance
characteristics.
TOGGLE
Another name for ZERO FLOAT.
ZERO BALANCE
The SIGNAL of the LOAD CELL in the NO LOAD
condition.
ZERO DEAD BAND
Another name for ZERO FLOAT.
ZERO FLOAT
The shift in ZERO BALANCE resulting from a
complete cycle of equal tension & compression
loads. Normally expressed in units of %FS and
usually characterized at FS = CAPACITY.
ZERO STABILITY
The degree to which ZERO BALANCE is maintained
over a specified period of time with all environmental
conditions, loading history, and other variables
remaining constant.
See APPENDIX articles for more detailed information
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ABBREVIATIONS
(All abbreviations are case-
specific, are not to be pluralized,
and do not use trailing periods.)
ampere A
combined error CE
degree Celsius ˚C
degree Fahrenheit ˚F
degree Kelvin ˚K
foot ft
foot-pound ft-lb
full scale FS
gram g
hertz Hz
inch in
inch-pound in-lb
kilogram kg
kilogram force kgf
kilonewton kN
kilopound (kip) K
kilopound force K lbf
meganewton MN
meter m
milliampere mA
millimeter mm
millivolt mV
millivolt/volt mV/V
minimum dead load MDL
newton N
newton-meter Nm
pound lb
pound-inch lb-in
pound-foot lb-ft
pound force lbf
pound per square inch psi
rated output RO
static error band SEB
ton, metric t
volt V
volt direct current VDC
volt alternating current VAC
watt W
FIGURE 1. ILLUSTRATION OF TERMS
