Yokogawa EJA310A - Manual (Page 31)

IM 01C21D01-01E 7-3
7. OPERATION
7.2.1 When you can obtain Low Range
Value from actual measured value
of 0% (0 kPa, atmospheric pres-
sure);
For pressure measurement using gauge pressure
transmitters, follow the step below before zero point
adjustment.
1) Close the tap valve (main valve).
2) Loosen the fill plug so that the pressure applied to
the transmitter is only the head of the seal liquid.
3) Adjust the zero point at this status.
4) After the adjustment, close the fill plug and then
gradually open the tap valve.
᭿ Using the Transmitter Zero-adjustment
Screw
Before adjusting a screw, check that the parameter
J20: EXT ZERO ADJ displays ENABLE. See
Subsection 8.3.3 (11) for the setting procedure.
Use a slotted screwdriver to turn the zero-adjustment
screw. Turn the screw clockwise to increase the output
or counterclockwise to decrease the output. The zero
point adjustment can be made with a resolution of
0.01% of the setting range. Since the degree of zero
adjustments varies with the screw turning speed, turn
the screw slowly for fine adjustment and quickly for
coarse adjustment.
᭿ Using the BT200
Zero point can be adjusted by simple key operation of
the BT200.
Select parameter J10: ZERO ADJ, and press the
ENTER key twice. The zero point will be adjusted
automatically to the output signal 0% (4 mA DC).
Confirm that the setting value displayed for the
parameter is ‘0.0%’ before pressing the ENTER key.
See Subsection 8.3.3 (11) for BT200 operating proce-
dures.
A display when parameter
J10 is selected.
Press key
twice for 0% output 4 mA DC.
SET
J10:ZERO ADJ
–0.0 %
+ 000.0
CLR ESC
F0705.EPS
7.2.2 When you cannot obtain Low Range
Value from actual measured value
of 0%;
Convert the actual measured value obtained by a digital
manometer or a glass gauge into %.
[Example]
The measuring range of 50 to 250 kPa; the actual
measured value of 130 kPa.
130–50
250–50
Actual measured value= x 100=40.0%
᭿ Using the Transmitter Zero-Adjustment Screw
Turn the screw to match the output signal to the actual
measured value in %.
᭿ Using the BT200
Select the parameter J10: ZERO ADJ. Change the
set point (%) displayed for the parameter to the actual
measured value (%), and press the ENTER key twice.
See Subsection 8.3.3 (11) for operation details.
Change setting to the actually
measured value (40.0%).
Press key twice
for 40% output 10.4 mA DC.
SET
J10:ZERO ADJ
–0.0 %
+ 040.0
CLR ESC
F0706.EPS
A display at J10 SET
J10:ZERO ADJ
–0.0 %
+ 000.0
CLR ESC