YOKOGAWA SC200, Instruction Manual

Page: 37 / 48

X.X
0
OFF
1 ON = 22 mA steady signal on
fault.
2 ON = 22 mA pulse during
30s at start of fault
then normal output.
IM 12D7B2-E-H
33
7-10. Temperature sensor adjustment
ACCESS-CODE :08 (see § 7-2)
DISPLAY
:*T.ADJ
Adjustment :Adjust the value of the
indicated temperature
(°C/°F) to that of the
actual temperature.
Explanation:
The temperature measurement is a two wire
resistance measurement. In this kind of
measurement the length of the connecting
cable can influence the accuracy of the tem-
perature indication. To compensate for the
extra resistance of the cable up to 5
Ω
can
be calibrated. Connect the correct tempera-
ture sensor to the EXA instrument and insert
it in a stable temperature bath of a known
value.
Check the temperature indicated at this set-
ting in °C or °F and adjust the value if
necessary.
Now the EXA transmitter has been calibra-
ted to compensate for the cable resistance.
7-11. Signalling of fail condition
ACCESS-CODE : 09 (see §7-2)
DISPLAY
: *BURN
Adjustment : X.X
Explanation:
Besides an indication at the display in the
field, sometimes an indication of errors in the
control room is also necessary. This is possi-
ble by sending a special signal over the 2-
wire connection to the receiving instrument.
A signal of 22 mA is used, because it is out-
side the normal analogue range of 4 to 20
mA. If at the receiving end an alarm is set to
the value represented by 22 mA, it is obvious
that the proper action can be taken from the
control room too. The signal uses the same
convention as used in thermocouple indica-
tions for detecting break of the sensor (burn-
out).
Default: 0 = OFF
7-12. Temperature compensation
coefficient adjustment
ACCESS-CODE : 10 (see § 7-2)
DISPLAY
: *T.C.
Adjustment : Adjust the value of the
manually set compensa-
tion factor
NOTE:
Access to this routine is only possible when
manually set temperature compensation
factor (
α
) is selected in §4-4.
Explanation:
In addition to the procedure described in
§4-4 it is possible to adjust the compenstion
factor directly. If the compensation factor of
the sample liquid is known from laboratory
experiments or has been previously determi-
ned, it can be introduced here.
Adjust the value between -10.00 to -10.00
% per °C. In combination with the reference
temperature setting at §7-4 a linear com-
pensation function is obtained, suitable for
all kind of chemical solutions.
K
t
- K
ref
x 100
α
=
X
T - T
ref
x K
ref
Default: skipped, compensation for NaCI
is automatic.