Yokogawa EJA438 - Manual (Page 28)

IM 1C22J1-01E 6-3
6. OPERATION
6.2.2 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.
Actual measured value=
ϫ
100=40.0%
130–50
250–50
᭿
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 7.3.3 (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
F0606.EPS
A display at J10 SET
J10:ZERO ADJ
–0.0 %
+ 000.0
CLR ESC
6.3 Starting Operation
After completing the zero point adjustment, use the
procedure below to start operation.
1) Confirm the operating status.
There will be cases in which the output signal
exhibits wide fluctuations (hunting) due to periodic
variation in the process pressure. In such cases,
BT200 operation can dampen the transmitter
output signal. Confirm the hunting using a receiv-
ing instrument or the integral indicator, and set the
optimum damping time constant. See Subsection
7.3.2 (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, SAA, and JIS Flameproof type
transmitters. 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
8-4)
After locking, the covers shoud be confirmed
not to be opened.
• Tighten the zero-adjustment cover mounting
screw to fix the cover in position.
6.4 Shutting Down Operation
Turn off the power.
NOTE
Whenever shutting down the transmitter for a
long period, detach the transmitter (diaphragm
seals) from the tank.