Yokogawa YTA320 - Manual (Page 30)

<6. Maintenance>
6-2
IM 01C50B01-01E
3. For thermocouple input
Since this instrument is equipped with a
reference junction compensating function, use
a reference junction compensating function
in universal calibrator in order to compensate
for this function upon calibration. According to
the reference milivolt table for thermocouple,
obtain milivolt corresponding to 0, 25, 50, 75,
or 100% of the span, and use that power as the
input value, then deliver it from the universal
calibrator to the temperature transmitter.
Measure the resulting output signal with the
voltage meter (digital multimeter) and check the
output value relative to the input value.
4. Thermometer resistor (RTD)
Using a thermometer resistor as input,
calibration of the temperature transmitter is
carried out via a 4- 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.
5. In Steps 2 through 4, 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, “BRAIN Protocol”
IM 01C50T03-01E or “HART Protocol” IM
01C50T01-01E and the instruction manual for
each terminal.
6.3 Disassembly and Assembly
This section details the procedure for part
replacement or disassembly and assembly of
each component depending on the maintenance
process.
Before starting disassembly and assembly work,
turn off the power, and use a tool suited to the
associated work.
Table 6.2 lists the tools required for disassembly
and assembly of the instrument.
Table 6.2 Tools for Disassembly and Assembly
Tool name Quantity Remark
Phillips screwdriver
Standard screwdriver
Hexagonal wrench
Crescent wrench
Torque wrench
Box wrench
Box screwdriver
Forceps
1
1
1
1
1
1
1
1
For M10 screw
CAUTION
Precautions for ATEX, IECEx and TIIS
Flameproof Type Transmitters
• For a withstand flameproof type transmitter,
as a rule, move the transmitter to a non-
hazardous location, then proceed with
maintenance and restore the instrument to
the original condition.
• For a withstand ATEX, IECEx and TIIS
flameproof type transmitter, turn the lock
bolt (hexagon socket bolt) clockwise with
a wrench for hexagon head, unlock and
remove the cover. When installing the
cover, it is the must to turn the lock bolt
counterclockwise and lock the cover (locked
to a torque of 0.7 Nm).
• For a withstand flameproof type transmitter,
in no case should the user be allowed to
modify the transmitter. Therefore, no user
is allowed to add a built-in indicator, or use
the transmitter with the indicator removed.
Contact us for any modification.
F0602.ai
Terminal cover
Lock bolt
CPU assembly
Stud bolt
Mounting screw
Amp. Cover
LCD board
(with indicator)
Figure 6.3 Mounting and Removal of Built-in
Indicator and CPU Assembly