Yokogawa EJA220A - Manual (Page 30)

IM 01C21C01-01E 7-3
7. OPERATION
7.2.2 When you cannot obtain Low Range
Value from actual measured value
of 0%;
Convert the actual measured value obtained by a glass
gauge into %.
[Example]
The measuring range of 0 to 2 m and the actual
measured value of 0.8 m.
0.8
2
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 (12) 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
7.3 Starting Operation
After completing the zero point adjustment, follow the
procedure below to start operation.
1) Confirm the operating status.
The output signal may widely fluctuate (hunting
state) due to process pressure periodic variation. In
such case, BT200 operation can dampen the trans-
mitter output signal. Confirm the hunting state 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.”
2) 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
Turn off the power.
NOTE
Whenever shutting down the transmitter for a
long period, detach the transmitter from the tank.
7.5 Venting or Draining Transmit-
ter Pressure-detector Section
Since this transmitter is designed to be self-draining
and self-venting with vertical impulse piping connec-
tions, neither draining nor venting will be required if
the impulse piping is configured appropriately for self-
draining or self-venting operation.
If condensate (or gas) collects in the transmitter
pressure-detector section, the measured pressure may
be in error. If it is not possible to configure the piping
for self-draining (or self-venting) operation, you will
need to loosen the drain (vent) screw on the transmitter
to completely drain (vent) any stagnated liquid (gas).
However, since draining condensate or bleeding off gas
gives the pressure measurement disturbance, this
should not be done when the loop is in operation.