Yokogawa EJA220A - Manual (Page 46)

IM 01C21C01-01E 8-14
8. BRAIN TERMINAL BT200 OPERATION
(b)-2 Follow the procedure below to use J11: ZERO
DEV.
ECS
ESC
SET
J11:ZERO DEV.
2.50 %
0 Since “J11: ZERO DEV.” contains
the previous correction, obtain the
correction value by adding 4.0% to
it. (2.50% + 4.0% = 6.50%)
Set the correction value, 6.50.
Press the key twice.
F0832.EPS
Present output is 41.0%.
Output error = 45.0 – 41.0 = 4.0%.
A10:OUTPUT (%)
41.0 %
The output is changed to 45%.
A10:OUTPUT (%)
45.0 %
SET
J11:ZERO DEV.
2.50 %
6.50
When the zero point is adjusted, the displayed value of
A40 is as follows.
[Example]
When the zero point is shifted by 20 kPa for the actual
pressure, the parameter of A40 indicates 50 kPa.
F0841.EPS
70 kPa
20 kPa
0 kPa
Zero adjustment
volume(J11)
Actual differential
pressure/pressure Input value
of A40
50 kPa
0 kPa
Zero
adjustment
(c) Zero Point Adjustment Using the External Zero
Adjustment Screw
• Enabling/inhibiting of zero point adjustment using the
external zero-adjustment screw on the transmitter
(J20: EXT ZERO ADJ)
Follow the procedure below to enable or inhibit zero
point adjustment from the zero-adjustment screw on
the transmitter.
This is set to “ENABLE” when the instrument is
shipped.
• Example: Inhibiting zero adjustment by the
external zero-adjustment screw
ESC
SET
J20:EXIT ZERO ADJ
ENABLE
< ENABLE >
< INHIBIT> Use the or key to
select INHIBIT.
Press the key twice to
enter the setting.
F0833.EPS
• Zero point adjustment using external zero-adjustment
screw on the transmitter
Turn the zero-adjustment screw on the outside of the
transmitter case using a slotted screwdriver. Turn the
screw to the right to increase the zero point or to the
left to decrease the zero output; the zero adjusts in
increments of 0.01% of the range setting.
Note that the amount of adjustment to the zero point
changes according to the speed at which the screw is
turned. To make fine adjustments, turn the screw
slowly; to make coarse adjustments, turn the screw
quickly.
Note: When a zero point adjustment has been made, do not turn off
the transmitter less than 30 seconds after adjustment.
(14) Span Adjustment
Each DPharp EJA series transmitter is factory charac-
terized according to the specification. Mounting
position effects or zero shifts caused by static pressure
are typically compensated by a zero adjustment.
A span adjustment is a function to correct the slope
error from a zero point in characterizing 100% point
(HRV). This function can be used when span drifts
may be caused or characterization to the specific
pressure standard is required.
Therefore, the zero point adjustment should always be
performed before the upper point adjustment in order
to maintain the pitch between zero and 100% points
within the calibration range.
You can manually perform the trimming procedure by
using J15: SPAN ADJ.
• Span adjustment value
The span adjustment value is calculated as follows.