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3.2.5 Module installation
(1) Installing modules contiguously
In QnA series PLCs, the left side of each I/O module is left open. When
installing an I/O module to the base, do not make any open slots between
any two modules. If there is an open slot on the left side of a module with
100/200VAC rating, the printed board which contains the hazardous
voltage circuit becomes bare. When it is unavoidable to make an open slot,
be sure to install the blank module (AG60).
When using the A5 B expansion base with no power supply, attach the
included cover to the side of the leftmost module.
3.2.6 Grounding
There are two kinds of grounding terminals as shown below. Either grounding
terminal must be used grounded.
Be sure to ground the protective grounding for the safety reasons.
Protective grounding
Functional grounding
3.2.7 External wiring
(1) 24VDC external power supply
For special modules that require a 24VDC I/O module or external power
supply, use a model whose 24VDC circuit is intensively insulated from the
hazardous voltage circuit.
(2) External connecting devices
When a device with a hazardous voltage circuit is externally connected to
the PLC, use a model whose circuit section of the interface to the PLC is
intensively insulated from the hazardous voltage circuit.
(3) Intensive insulation
Intensive insulation refers to the insulation with the dielectric withstand
voltage shown in Table 2.
Rated voltage of hazardous
: Maintains the safety of the PLC and improves
the noise resistance.
: Improves the noise resistance.
Table2 : Intensive Insulation Withstand Voltage
(Installation Category II, source : IEC664)
voltage area
150 V AC or less
300 V AC or less
Surge withstand voltage
17
(1.2/50 μs)
2500V
4000V
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