Yokogawa EJX930A - Manual (Page 50)

<8. Operation>
8-3
IM 01C25R01-01E
The zero-adjustment screw is located inside the
cover.
Use a slotted screwdriver to turn the zero-
adjustment screw. Equalize the transmitter, then
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. The degree of zero
adjustments varies with the screw turning speed;
turn the screw slowly to make a fine adjustment,
quickly to make a rough adjustment.
8.2.2 Adjusting Zero Point for Static
Pressure
Zero point adjustment for static pressure can
be adjusted with the HART Communicator or
FlowNavigator.
(1) When you can obtain the Low Range Value
from the actual measured value of 0% (0
MPa pressure);
Apply zero pressure in % to the transmitter. After
obtaining a stable pressure, adjust the zero point.
(2) When you cannot obtain the Low Range
Value from the actual measured value of
0%;
Adjust the transmitter output to the actual measured
value obtained by a highly accurate master meter
such as digital manometer.
Example:
Range: 0 to 16 MPa abs
Actual measured value: 2.000 MPa abs
Transmitter s output: 2.1 MPa abs
Lower SP trim deviation
(SP Manual Lower Pt): – 0.3 MPa abs
F0804.ai
EJX-MV:YOKOGAWA
SP trim mode:
1 Off
2 Auto, Lower Pt
3 Auto, Upper Pt
4 Manual Lower Pt
5 Manual Upper Pt
ABORT ENTER
(ENTER)
‘-0.4’
EJX-MV:YOKOGAWA
SP for trim 0.2100
manual, Lower Pt
-0.3000 MPa
-0.4
HELP ABORT ENTER
SP for trim is 2.1000
Master meter shows 2.0 MPa abs
= 2.0-2.1
= -0.1
< Calculation of correction value>
= The deviation value for SP zero adjustment
+ error value for SP zero adjustment
= (-0.3)+(-0.1)
=-0.4
1. Device setup
2. Diag/Service
3. Calibration
4. SP sensor trim
1. SP trim
ENTER (F4)
×3
1
2
2
DEL
8.2.3 Adjusting Zero Point for External
Temperature
Zero point adjustment for external temperature
can be adjusted by the HART Communicator or
FlowNavigator.
As defined the reference resistor value table of
the thermometer resistor (RTD), obtain resistance
value corresponding to 0%, and use the obtained
resistance as the input value, then deliver it to the
transmitter by means of a variable resistor.
Measure the resulting output signal with the
voltmeter (digital multimeter), and check the output
value relative to the input value.
Zero point can be adjusted by the HART
Communicator's easy key operation.