Yokogawa EJX930A - Manual (Page 54)

<9. Maintenance>
9-2
IM 01C25R01-01E
9.3.2 External Temperature (RTD)
Using a thermometer resistor as input, calibration
of the temperature transmitter is carried out via a
3-core wire connection.
As defined the reference resistor value table of
the thermometer resistor (RTD), obtain resistance
values corresponding to 0, 25, 50, 75 or 100%
of the span, and use the obtained resistance as
the input value, then deliver it to the temperature
transmitter by means of a variable resistor. Measure
the resulting output signal with the voltmeter (digital
multimeter) and check the output value relative to
the input value.
If the output signal deviates from the given range
of accuracy when a given input signal is delivered,
adjust the output using the handheld terminal.
For details of how to adjust the output, refer to
the additional references, “HART Protocol” IM
01C25R02-01E and the instruction manual for each
terminal.
Table 9.1 Instruments Required for Calibration
Name Yokogawa-recommended Instrument Remarks
Power supply Model SDBT or SDBS distributor 4 to 20 mA DC signal
Load resistor Model 2792 standard resistor [250 Ω ±0.005%, 3 W]
Load adjustment resistor [100 Ω ±1%, 1 W]
Voltmeter Model 2501 A digital multimeter
Accuracy (10V DC range): ±(0.002% of rdg + 1 dgt)
Digital
manometer
Model MT220 precision digital manometer
1) For 10 kPa class
Accuracy: ±(0.015% of rdg + 0.015% of F.S.). . . . for 0 to 10 kPa
±(0.2% of rdg + 0.1% of F.S.). . . . . . . . for -10 to 0 kPa
2) For 130 kPa class
Accuracy: ±0.02% of rdg. . . . . . . . . . . . . . . . . . . . for 25 to 130 kPa
±5 digits . . . . . . . . . . . . . . . . . . . . . . . . for 0 to 25 kPa
±(0.2% of rdg + 0.1% of F.S.). . . . . . . . for -80 to 0 kPa
3) For 700 kPa class
Accuracy: ±(0.02% of rdg + 3 digits) . . . . . . . . . . . for 100 to 700 kPa
±5 digits . . . . . . . . . . . . . . . . . . . . . . . . for 0 to 100 kPa
±(0.2% of rdg + 0.1% of F.S.). . . . . . . . for -80 to 0 kPa
4) For 3000 kPa class
Accuracy: ±(0.02% of rdg + 10 digits). . . . . . . . . . for 0 to 3000 kPa
±(0.2% of rdg + 0.1% of F.S.). . . . . . . . for -80 to 0 kPa
5) For 130 kPa abs class
Accuracy: ±(0.03% of rdg + 6 digits) . . . . . . . . . . . for 0 to 130 kPa abs
Select a manometer having
a pressure range close to
that of the transmitter.
Pressure
generator
Model 7674 pneumatic pressure standard for 200 kPa {2 kgf/cm 2 }, 25 kPa
{2500 mmH 2 O}
Accuracy: ±0.05% of F.S.
Requires air pressure
supply.
Dead weight gauge tester 25 kPa {2500 mmH 2 O}
Accuracy: ±0.03% of setting
Select the one having a
pressure range close to that
of the transmitter.
Pressure
source
Model 6919 pressure regulator (pressure pump)
Pressure range: 0 to 133 kPa {1000 mmHg}
Prepare the vacuum pump
for negative pressure
ranges.
Variable
resistor
279301 type 6-dial variable resistor (accuracy: ±0.005%) For calibration of
thermometer resistor (RTD)
input
Note: The above table contains the instruments capable of performing calibration to the 0.2% level. Since special maintenance and
management procedures involving traceability of each instrument to higher-level standards are required for calibration to the 0.1%
or higher level, there may be difficulties in calibration to this level in the field. For calibration to the 0.1% level, contact Yokogawa
representatives from which the instrument was purchased or the nearest Yokogawa office.