Honeywell SC1000 - Manual (Page 113)

SC Series Instruction Manual page 113
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12
12.6.4
CALIBRATION TYPE
Menu Item
This chooses the type of calibration technique to be used. There are two methods
that can be used to calibrate the transducer to the Input Channel. Each has
advantages and disadvantages as described in the table below.
It is important to know your application in order to select the appropriate cali-
bration type. When the best possible accuracy is required, Known-Load Calibra-
tion is recommended. However, if known-loads are not available, Shunt
Calibration may be used instead.
The choices for this menu item are:
• “
TYPE= SHUNT CAL
” means Shunt Calibration. First, you are prompted to apply
the load entered in the “
ZERO SCALE VALUE
” register. Next, the instrument inter-
connects the Shunt Cal 1 and Shunt Cal 2 pins. This activates the trans-
ducer’s or in-line amplifier’s shunt calibration circuit which causes a
predictable apparent signal. The instrument then takes a reading and adjusts
itself using the “
SHUNT CAL VALUE
” register.
• “
TYPE= 2 POINT CAL
” means 2-Point Known Load Calibration. You are prompted
to apply the loads to the transducer that were entered in the “
KNOWN POINT 1/2
”
and “
KNOWN POINT 2/2
” registers. This technique assumes that the transducer is
linear, so the usual loads used are zero scale and full scale.
• “
TYPE= 3 POINT CAL
” means 3-Point Known Load Calibration. You are prompted
to apply the loads to the transducer that were entered in the “
KNOWN POINT 1/3
”
and “
KNOWN POINT 2/3
” and “
KNOWN POINT 3/3
” registers. This technique can be
Table 1-7: Comparison of Calibration Types
Shunt Calibration
2-, 3-, or 5-point
Known Load
Calibration
RECOMMENDED...
...for most applications no yes
...when frequently swapping
transducers
yes no
...when best possible accuracy
required
no yes
PROS and CONS
Relative accuracy good best
Requires actual, calibrated loads
to be applied
no yes
CALIBRATION TECHNIQUE
Zero-scale point from... applied load applied load
Full-scale point from... transducer output
when Shunt Cal pins
connected
applied load
Linearity correction from... N/A 2-point: none
3- or 5-point:
applied load