Yokogawa EJX930A - Manual (Page 167)

<Appendix 8. Advanced Diagnostics>
A8-23
IM 01C25T02-01E
A8.3.1 FLG_TEMP_COEF Setting
The value calculated according to the following
procedure is set to the FLG_TEMP_COEFF.
• To enhance the calculation accuracy of the
flange temperature, measure the actual flange
temperature by using the temperature sensor
etc.
• Calculate the ratio of the capsule temperature
to the capsule temperature minus the amplifier
temperature from the two temperature values
measured by EJX.
• Derive the FLG_TEMP_COEF from the
measured flange temperature and the ratio
of the capsule temperature to the amplifier
temperature in accordance with the following
calculation formula.
FLG_TEMP_COEFF(C
f
) =
(Actual measured value of Flange temperature) - CT
CT - AT
A8.3.2 Alert and Alarm Setting
The abnormal results of flange temperature (heat
trace monitoring) are given by an alert or the LCD
display of alarm status.
The flange temperature changes when the heat
trace breaks or the abnormal temperature is
detected due to the failure.
The abnormal results are stored in the bit 13 and
14 of DIAG_ERR in the SENSOR Transducer
Block when the flange temperature is out of the
range between the limits preset to the following
parameters.
• FLG_TEMP_H_LIM
• FLG_TEMP_L_LIM
Generating an alarm or alert is set by DIAG_
OPTION.
Refer to A8.2.5 for the detail.
A8.3.3 Assignment of FLG_TEMP_VAL to
Process Value (PV) in AI Function
block
The EJX has four AI function blocks which of
each has one channel. If set 6 to the channel of AI
function block, the FLG_TEMP_VAL is assigned to
Process Value (PV) in AI function block. The unit of
the flange temperature follows the setting of XD_
SCALE in the assigned AI function block.
To Assign CAP_TEMP_VAL or AMP_TEMP_VAL to
Process Value (PV) in AI function block, set 4 or 5 to
the channel of AI function block.
A8.3.4 Analog Alert
Since Flange temperature is assigned to an AI
Function Block, an analog alert can be generated
by OUT_D in AI Block.
For the detail of the analog alert setting, refer to
6.6.5.
A8.3.5 Out of Temperature Measurement
Range
If the measurement value of the capsule
temperature or the amplifier temperature is out of
the measurement range, the OUT signal status
of PRIMARY_VALUE, SECONDARY_VALUE,
and TERTIARY_VALUE becomes “Uncertain-
Subnormal" and the status of CAP_TEMP_VAL,
AMP_TEMP_VAL, and FLG_TEMP_VAL become
“Uncertain-Sensor Conversion not Accurate”.
The measurement range of the capsule
temperature and the amplifier temperature is as
follows.
• Amplifier temperature: -40 to 85°C
• Capsule temperature: -40 to 120°C
The out of range is detected by the margin of 10°C
added with the measurement range.