Yokogawa Value Series FX1000 - Manual (Page 253)

12-4
IM 04L21B01-01EN
12.4 Input Signal Wiring
WARNING
• To prevent electric shock while wiring, make sure that the power supply is turned
off.
CAUTION
• Applying a strong tension to the input and output signal cables connected to the FX
may damage the cables or the FX terminals. To avoid applying tension directly to
the terminals, fix all cables to the rear of the mounting panel.
• To prevent fire, use signal cables with a temperature rating of 70°C or more.
• Do not apply voltages that exceed the following values to the input terminals. Doing
so may damage the FX.
• Maximum input voltage: ±60 VDC
• Maximum common mode voltage: ±60 VDC (under measurement category II
conditions)
• The FX is an installation category II product.
Precautions to Be Taken While Wiring
Take the following precautions when wiring the input signal cables.
When using a screw terminal, we recommend that you use a crimp-on lug with an
insulation sleeve (designed for 3 mm screws).
Crimp-on lug (designed for 3 mm screws) with an insulation sleeve
Take measures to prevent noise from entering the measurement circuit.
• Move the measurement circuit away from the power cable (power circuit) and ground
circuit.
• Ideally, the object being measured should 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 the noise caused by electrostatic induction.
Connect the shield to the ground terminal of the FX 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 (we recommend a
cross sectional area of 0.5 mm 2 or less).
• 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 other instruments on or off during operation. This can have adverse effects
on the other instruments.
• RTDs cannot be wired in parallel.