POSITION TRANSMITTERS
CALIBRATION
A - 8
b. Loosen the set screw on the hub of the small gear using a
-in. Allen wrench (Fig. A-5 and Table A-2).
c. Use a screwdriver to adjust the shaft on the potentiometer
until the ohmmeter reads 1000, ±10 Ω. While adjusting the
resistance, hold the gears and cam shaft stationary so rotation
does not occur. Only the potentiometer shaft should move
while adjusting the resistance.
NOTE: If the mesh between the large and small gears is not
tight, adjust the position of the potentiometer mounting bracket
(Fig. A-5 and Table A-2) so that backlash is eliminated.
d. Tighten the set screw on the small gear hub.
e. Remove the ohmmeter from TB1-1 and TB1-2. Install the
cam, screw, flag, nut and washer (Fig. A-5 and Table A-2).
4. Place the CAL/OPER jumpers into the operate (OPER) posi-
tion (Fig. A-4). If a direct acting cam is being used, place the FOR/
REV jumpers in the FOR position. For a reverse acting cam, place
these jumpers in the REV position (Fig. A-4).
5. Connect a 24-VDC external power supply across TB1-1 and
TB1-2.
6. Move the actuator to the 0% position. Insert ammeter leads
into TP2(+) and TP1(-). If the position of the cam limits access to
TP1, connect the (-) lead to TB1-2 on the terminal block.
7. Adjust the zero potentiometer to 4.00 mA. Refer to Figure A-4
for the location of the zero potentiometer.
8. Move the actuator to the 100% position. Adjust the span
potentiometer to 20.00 mA. Refer to Figure A-4 for the location of
the span potentiometer.
9. Repeat Steps 7 and 8 until the indicated current readings are
obtained.
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