DayTronic IL78A Manuel - Page 11

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3. CALIBRATION
This section contains the instructions for calibrating the IL78A. Included is a functional description of
the instrument front-panel (see Figure 2). To perform calibration, proceed as follows.
Turn power ON to the IL78A DC Power input terminal (11 to 28 Vdc input) The
(a)
front-panel indicator should light green to indicate the application of dc power.
Allow 10 minutes of warmup for stabilization of transducer characteristics.
Remove the top cover of the unit to make the proper connections and adjustments.
Set the Coarse Zero control to position 8 and the Coarse Span control to position 0.
(b)
Position the front panel switches to the desired settings for the application. Refer
(c)
to Figure 2 for details. If using Shunt method, refer to step (k).
With the transducer unloaded, adjust the Coarse Zero control and the Fine Zero control until
(d)
the desired analog output is achieved. If greater zero authority is desired, place the front panel
Switch 7 - "Zero Adj" to the extended range. This will allow the user to obtain 100% zero offset
control. The Normal postion of switch 7 allows for approximately 25% Zero authority.
Load the transducer in the positive direction with a convenient dead weight value (greater than one
(e)
half of full scale). Adjust Coarse Span for a nominal corresponding output. Adjust the PHASE control,
until a maximum output value is obtained. (Once set for your transducer, this PHASE ADJUSTMENT
step need not be repeated unless a change in cable length – or transducer – is required). Unload the
sensor and re-Zero as needed.
f the calibration will utilized a known "dead-weight", re-load the sensor and adjust the Coarse and
I
(f)
Fine Span controls for the expected analog output value. Unload - Zero and Load - Span operations
may need to be repeated for analog output precision.
Note: With sensor unloaded, activate & record "SHP" value for furture calibration verification.
If the calibration will utilize the "Shunt" calibration method, refer to step (k).
(g)
If the transducer is to be also used in the negative realm, load the transducer in
(h)
the negative direction with the same dead weight value as used in step (f) and confirm
that the dead weight reading obtained is the same, but negative polarity, as that of step
(f). If not, see steps (i) thru (j).
A Symmetry adjustment is provided to compensate for transducers that do not have
(i)
symmetrical sensitivity characteristics. This adjustment is factory set assuming
symmetrical characteristics. If step (h) indicates that a field adjustment is necessary,
proceed as follows.
AC Strain Gage Conditioner Module
(cont.)
IL78A
Calibration IL78A.3