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IM 06B00A01-01EN
• The sheath can be bent providing that the bending
radius is larger than the twice of the sheath diameter.
However, the sheath will be damaged if it changes
the form again. When you bend the sheath in
the field, we recommend that the bending radius
keep larger than five times of the sheath diameter.
The metal sheathed resistance thermometers
have resistance element in the top of the sheath.
Therefore, do not bend the portion of the sheath with
100 mm length from the top.
• If the connection part of temperature sensors and
lead cables are exposed to high temperature,
the insulation resistance may be declined or the
measuring error may be increased. Therefore, keep
the temperature of the part at 80°C or less except
products for high temperature application.
• If the polarity is incorrect, it is impossible to measure
the correct temperature. Pay attention the color of
compensating cables because those colors change
with sensor type.
2.2 Maintenance and Inspection
• Flameproof sensors shall not be maintenance-
serviced with its power turned on. However, in cases
where maintenance servicing is to be conducted with
the power turned on, with the terminal head cover
removed, always use a gas detector to check that
there is no explosive gas in that location.
Do not attempt to change specifications about
flameproof sensors.
• Since there are many cases of high temperature in
the plant where temperature sensors are installed, it
is very dangerous to maintain or inspect temperature
sensors during operation or just after shutdown.
• If the temperature sensors are used as footing, they
might be damaged.
2.3 Storage
• Store temperature sensors in dry and clean place.
When temperature sensors are kept in the place of
high humidity, the insulation resistance of them may
decline.
3. Wiring
Note that lead cables to connect temperature sensor
for thermocouple and for resistance are diffent.
(1) Thermocouples
For the extention wires, use the standrad
compensation lead wires recommended for each
thermocouple type. Incorrect use of compensation
wire type causes a large error. The color of wire
covering changes with type of compensation lead
wires and standard such as JIS, ASTM, IEC, etc. Also
pay attention to the polarity of compensation wires
when connect them.
(2) Resistance thermometer sensor
Since 3-wire method is adopted in resistance
thermometer measurement usually, each sensor
requires 3 wires. The terminal symbols are described
as A, A, and B.
A
A
A
B
B
B
B
B
B
Thermocouple’s
Terminal Block
Resistance Thermometer
Sensor’s Terminal Block
–
+
–
+
F01E.ai
Figure 1. Terminal Blocks
4. Grounding
In case the temperature sensor is connected with a
receiver, a shield cable may be grounded in order to
avoid the influence of the noise. Generally, one-point
grounding is recommended.
Please refer to Figure 2 about the grounding points.
Thermocouples
Compensation lead wire
Shield
Sheath
Thermocouples
Compensation lead wire
Shield
Sheath
Grounding
Grounding
Grounding
Reciever
Reciever
F02E.ai
Figure 2. Grounding of Shield
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