DayTronic IL70A Handmatig - Pagina 9

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3. CALIBRATION

Calibration of the IL70A is accomplished by the conventional shunt technique, using an internally

installed calibration resistor, or via the "dead-weight" method.

Calibration Resistor. If a fixed resistor is shunted across one arm of a strain gage bridge, it produces an

unbalance equivalent to that of a particular value of mechanical input. If this Equivalent Input value is

accurately known, it can be used as a reference point for shunt calibration of the system. Upon

completion of installation of the transducer and its associated cabling, the user can:

Perform an overall dead weight calibration using a precisely known value

(1)

of mechanical input. The calibration can then be transferred to the installed

calibration resistor for convenience in subsequent checking.

Use an external shunt resistor, please refer to the notes on page one of this manual. The

(2)

installed calibration resistor is typically supplied by the transducer manufacturer or is

referenced on the calbiraiton sheet that accompanies the tranducer. Using a known shunt

resistorance can achieve a precisely known Equivalent Input allowing the instrument

sensitivity to be adjusted correctly. Note, this shunt resistor may reside in the transducer

itself and is accessed via the input pins of the sensor.

Determine the Equivalent Input value for the internally installed 59K calibration resistor,

(3)

knowing the transducer sensitivity, and adjust the instrument sensitivity accordingly. Place the

jumper on the IL70A to "INT" to enable the 59K Ohm resistor.

A one percent, 59-kilohm calibration resistor is installed in the IL70A at the factory. The installed

resistor can usually be used even though the transducer calibration data mentions some

other resistance value. In Section 4 of this manual, the techniques described above are

demonstrated. If, however, the installed value of calibration resistor is not appropriate

for the transducer and the measurement range to be used, an external "EXT" shunt resistor

should be installed. The external calibration resistor is installed from the "CAL Sense"

terminal to either the + Signal or - Signal teminals depending on your polarity direction

when using the provided "shunt" switch. Note: A variety of DC Load Cells and Slip Ring

Torque Transducers are supplied with the appropriate calibration resistor integral to the

transducer. When this type of transducer is used it will be necessary to place the jumper in

"EXT" and connect the "Cal Sense" line to the appropiate pin on the transducer.

This section contains the instructions for calibrating the IL70A. Included is a functional

description of the instrument front-panel (see Figure 2). To perform calibration, proceed

as follows with the sensor or calibration standard connected.

Turn power ON to the IL70A DC Power input terminal (11 to 28 Vdc input) The front-

(a)

panel indicator should light green to indicate the application of DC power. Allow 10

minutes of warmup for stabilization of transducer characteristics.

DC Strain Gage Conditoner Module

IL70A

Calibration

IL70A.3