Yokogawa Button Operated DX2000 - Manual (Page 54)

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IM 04L42B01-02E
Installation and Wiring
Input Signal Wiring
WARNING
• To prevent electric shock while wiring, ensure that the power supply source is
turned OFF.
CAUTION
• If a strong tension is applied to the cable wired to the DX, the terminals of the DX
and/or the cable can be damaged. In order to prevent tension from being applied
directly on the terminals, fasten all wiring cables to the rear of the mounting
panel.
• To prevent fire, use signal wires having a temperature rating of 70°C or more.
• Do not apply a voltage exceeding the following value to the input terminals.
Otherwise, damage to the DX may result.
• Maximum input voltage: ±60 VDC
• Maximum common mode voltage: ±60 VDC (under measurement category II
conditions)
• The DX is a product of installation category II.
Precautions to Be Taken While Wiring
Take the following precautions when wring the input signal cables.
When using a screw terminal, we recommend that you use a crimp-on lug
with an insulation sleeve (designed for 4-mm screws).
Crimp-on lug with insulation sleeves (for 4 mm screws)
When using a clamp terminal (/H2), we recommend that you use the
following kind of cable:
• Conductive cross-sectional area: 0.08 mm 2 to 1.5 mm 2 (AWG 28 to 16)
• Length of the stripped section of the wire: Approx. 7 mm
Take measures to prevent noise from entering the measurement circuit.
• Move the measurement circuit away from the power cable (power circuit) and ground
circuit.
• It is desirable that the object being measured does not generate noise. However, if
this is unavoidable, isolate the measurement circuit from the object. Also, ground the
object being measured.
• Shielded wires should be used to minimize noise caused by electrostatic induction.
Connect the shield to the ground terminal of the DX as necessary (make sure you are
not grounding at two points).
• To minimize noise caused by electromagnetic induction, twist the measurement circuit
wires at short, equal intervals.
• Make sure to earth ground the protective ground terminal through minimum resistance
(less than 100 Ω).
When using internal reference junction compensation on the thermocouple
input, take measures to stabilize the temperature at the input terminal.
• Always use the terminal cover.
• Do not use thick wires which may cause large heat dissipation (cross sectional area of
0.5 mm 2 or less recommended).
• Make sure that the ambient temperature remains reasonably stable. Large
temperature fluctuations can occur if a nearby fan turns ON or OFF.
Connecting the input wires in parallel with other devices can cause signal
degradation, affecting all connected devices. If you need to make a parallel
connection, then
• Turn the burnout detection function OFF.
• Ground the instruments to the same point.
• Do not turn ON or OFF another instrument during operation. This can have adverse
effects on the other instruments.
• RTDs cannot be wired in parallel.