2-3
IM 707231-01E
Hardware Preparation
2
2.2 Connecting the 30-CH Scanner Box and the
Input Signal Wire
You cannot connect the input signal wires directly to the 30-CH Fast Digital Thermometer
Module WE7231. To connect the input signal wires, you need the 30-CH Scanner Box
(model 707815, sold separately).
Connecting the 30-CH Scanner Box to the Input Signal Wire
WARNING
• There is a danger of electric shock between the input terminals since they only
have functional isolation. Functional isolation means isolation that removes the
effect of noise from the electric potential difference occurring between 2 points,
and is intended to satisfy measurement specifications rather than to provide
protection from electric shock.
• The guard terminal is common within groups (CH1-CH15 and CH16-CH30).
Also the guard terminal is connected to the L terminal of the measurement
channel inside the module. If the potential of the L terminal at each channel
differs, the module or connected device may be damaged so don’t use the guard
terminal.
CAUTION
• Do not apply a voltage exceeding the following levels, as it may damage the
module.
Maximum allowable input range:
30 VACrms, 42.4 Vpeak or
±
60 VDC between
H and L.
(Overvoltage category: CAT I and II)
Maximum noise across channels: 60 VACrms or
±
100 VDC
• Do not apply the voltage exceeding 60 VACrms or
±
100 VDC between input
channels, as it may damage the module and 30-CH Scanner Box.
• Remove the 30-CH Scanner Box from the module when connecting the signal
wires to avoid damaging the module.
• Do not apply voltage between the L terminal and guard terminal (terminal with
the G signal) as this may result in damage to the module and any connected
devices. The guard terminal is connected to the circuit common inside the
module. When measuring voltage, the guard terminal and L terminal form a
direct connection since the L terminal is connected to the circuit common. Also,
when measuring resistance, L terminal is the standard for the circuit common.
Note
• When performing internal reference junction compensation on the thermocouple input, consider
the following suggestions for stabilizing the temperature at the terminal section.
• Make sure the terminal cover is in place.
• Keep the temperature constant in the area where the instrument is operating.
• Do not use thick wires (a cross sectional area of 0.5 mm
2
or more) that have large radiation
effects.
• Place the 30-CH Scanner Box at a sufficient distance from the point of measurement so that
the heat from the point of measurement will be conducted through the wiring rather than to
the 30-CH Scanner Box.
• To prevent noise, you can use the functional grounding terminal on the side of the 30-CH
Scanner Box to ground the guard terminal or L terminal (see next page).
