 Technical
Definitions of Terminology
(1) Rated
Capacity(R.C.) The maximum axial loads that
load cells are designed to measure within its specification.
(2) Rated Output(R.O) The algebraic difference
between the outputs at noload and at rated load.
Usually load cell output is specified in millvolts
per volt at rated capacity. (3) Nonlinearity
The maximum deviation of the calibration curve
from a straight line between zero and rated load
outputs,expressed as a percent of the rated output
and measured on increasing load only. (4) Hysteresis
The maximum difference between output readings
for the same applied load one point obtained while
decreasing from rated output. The points are taken
on the same continuous cycle. The deviation is expressed
as a percent of rated output. (5) Repeatability
The ability of a load cell to reproduce output
readings when the same load is applied to it consecutively,
under the same direction. Repeatability is expressed
as the maximum difference between output readings
as a percent of rated output. (6) Zero balance
The output signal of the load cell with rated
excitation and with on the applied, usually expressed
in percent of rated output. (7) Temperature
range,compensated The range of temperature
over which the load cell is compensated to maintain
rated output and zero balance with specific limits.
(8) Temperature range ,Safe The range
of temperature over which the load cell may be safely
operated up to full scale without causing failure
but specifications may not be met. (9) Temperature
effect on rated output The change in rated
output due to a change in ambient temperature. Usually
expressed as +/ a percentage change in rated output
per degree C changes in ambient temperature, over
the compensated temperature range. (10) Temperature
effect on zero balance The change in rated
output due to a change in ambient temperature. Usually
expressed as +/ percentage changes in rated output
per degree C change in ambient temperature, over
the compensated temperature range. (11) Terminal
resistance , input The resistance of the load
cell circuit measured at the excitation terminal,
at standard temperature, with noload applied, and
with the output terminals opencircuited. (12)
Terminal resistance, output The resistance
of the load cell circuit measured at the output
signal terminals, at standard temperature, with
noload applied, and with the excitation terminals
opencircuited. (13) Insulation resistance
The DC resistance expressed in ohms measured
between any electrical connector pin or lead wire
and the load cell body or case. Normally measured
at 50V DC (14) Excitation The voltage
or current applied to the input terminals of the
load cell. (15) Safe overload The maximum
load in percent of rated capacity, which can be
applied without causing a permanent change in the
performance specifications. (16) Ultimate overload
The maximum load in percent of rated capacity,
which can be applied without producing a structural
failure. (17) Creep The change in load
cell output occurring with time, while under load,
and with all environmental conditions and other
variables remaining constant. Usually measured
with rated load applied and expressed as a percent
of rated output over a specific period of time.
(18) Accuracy Stated as a limit tolerance,
which defines the average deviation between the
actual output versus theoretical output. In practical
load cell applications, the potential errors of
nonlinearity, hysteresis, repeatability and temperature
effects do not normally occur simultaneously, nor
are they necessarily additive. Therefore, accuracy
is calculated based upon the RMS value of potential
errors, assuming a temperature band of +/ 10 C,
full rated load applied, and proper set up and calibration.
Potential errors of the readout, cross talk, or
creep effects are not included.





MultiTransducer
Summing Box Model : SB4P The SummingJunction
box is a multi cell interface for signal conditioning
and load cell indicating instruments.
Many weighting systems used multiple load cells
and therefore require a summing junction box
to tie or sum the load cell signals together,allowing
a digital weight indicator to read a single system
signal. The Summing process actually wires
multiple load cells so that all their signal lines
and excitation lines are in parallel,providing
instantaneous electronic summing of the signals.
Load cell summing is necessary because:
~Weight distribution in multiple load cell
systems is not equal at load cell. The vessel loading
process and the characteristics of the material
and many other factors affect weight distribution
on the load cells. ~It is virtually impossible
to make each load cell exactly alike. Load cell
manufacturing process tolerances allow for
some variance in individual cell specifications
.This variance,if unchecked,would not allow for
the kinds of accuracy required in modern process
applications. Installing the load
cell & summing box 1. Supply a power
to the indicator after distributing power lines.
2. Set up indicator as indicated in the instruction.
3. Test the calibration indicated as in the
instruction of Digital indicator. 4. Press
a quarter of maximum capacity on the upper parts
of load cells which is to be adhered. 5. There
are unbalanced load points, which is happened by
the load of system. 6. Turn the multi turn
resistivity of a summing box to the right direction
to go up the load,or left. 7. Coordinate repeatedly
the multi turn resistivity like the case of No.5
above to even up the load of 4 points
8. Set on calibration as indicated in the digital
indicator.

