Yokogawa EJA110A - Manual (Page 35)

IM 01C21B01-01E 7-3
7. OPERATION
᭿ 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 (15) 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
7.3 Starting Operation
After completing the zero point adjustment, follow the
procedure below to start operation.
1) Close the equalizing valve.
2) Gradually open the low pressure stop valve.
This places the transmitter in an operational condi-
tion.
3) Confirm the operating status. If the output signal
exhibits wide fluctuations (hunting) due to periodic
variation in the process pressure, use BT200 to
dampen the transmitter output signal. Confirm the
hunting using a receiving instrument or the integral
indicator, and set the optimum damping time
constant. See Subsection 8.3.3 (3), “Damping Time
Constant Setup.”
4) After confirming the operating status, perform the
following.
IMPORTANT
• Remove the BT200 from the terminal box, and
confirm that none of the terminal screws are
loosened.
• Close the terminal box cover and the amplifier
cover. Screw each cover in tightly until it will
not turn further.
• Two covers are required to be locked on the
CENELEC and IECEx Flameproof type trans-
mitters. An Allen head bolts (shrouding bolts)
are provided under edge of the each cover for
locking. When a shrouding bolts are driven
counterclockwise by an Allen wrench, it is
coming out and locks up a cover. (See page 9-
3) After locking, the covers should be con-
firmed not to be opened by hand.
• Tighten the zero-adjustment cover mounting
screw to fix the cover in position.
7.4 Shutting Down Operation
Shut down the transmitter operation as follows.
1) Turn off the power.
2) Close the low pressure stop valve.
3) Open the equalizing valve.
4) Close the high pressure stop valve.
5) Close the high pressure and low pressure tap
valves.
NOTE
• Whenever shutting down the transmitter for a
long period, remove any process fluid from the
transmitter pressure-detector section.
• The equalizing valve must be left OPEN.