IM 01C25R01-01E
8-3
8. OPERATION
8.2.2 Adjusting Zero Point for Static
Pressure
Zero point adjustment for static pressure can be adjusted
with the HART Communicator or EJXMVTool.
(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):
– 0.3MPa abs
F0805E.EPS
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
<Calculation of error value>
= 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 EJXMVTool.
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.
8.3 Starting Operation
After completing the zero point adjustment, follow the
procedures below to start operation. Steps 1) and 2) are
specific to the differential pressure transmitters.
1) Close the equalizing valve.
2) Gradually open the low pressure stop valve.
This places the transmitter in an operational
condition.
3) Confirm the operating status. If the output signal
exhibits wide fluctuations (hunting) due to periodic
variation in the process pressure, use the communi-
cator to dampen the transmitter output signal.
Confirm the hunting using a receiving instrument or
the integral indicator, and set the optimum damping
time constant.
4) After confirming the operating status, perform the
following.
IMPORTANT
• Remove the communicator from the terminal
box, and confirm that none of the terminal
screws are loose.
• Close the terminal box cover and the amplifier
cover. Screw each cover in tightly until it will
not turn further.
• There are two covers that must be locked on
the ATEX Flameproof type transmitters. An
Allen head bolt (shrouding bolt) under the edge
of each cover is used to lock the cover. When
the shrouding bolt is driven counterclockwise
with an Allen wrench, the bolt rotates upward
and locks the cover. (See section 9.4.) After
locking the covers, confirm that they are secure
and cannot be opened by hand.
Tighten the zero-adjustment cover mounting
screw to secure the cover.
• Tighten the zero-adjustment cover mounting
screw to secure the cover.
