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11 EMC AND LOW VOLTAGE DIRECTIVE
MELSEC-ST
11.2.5 Grounding
There are the following two different ground terminals.
Either of them must be grounded for use.
Protective grounding
: Maintains the safety of the MELSEC-ST series and
improves the noise resistance.
Functional grounding
: Improves the noise resistance.
11.2.6 External wiring
(1) External power supply
For the MELSEC-ST series I/O modules and the intelligent function modules
which require external supply power, use a model of which 24VDC circuit is
reinforced-isolated from the hazardous voltage circuit.
(2) External devices
When a device with a hazardous voltage circuit is externally connected to the
MELSEC-ST series, use a model of which circuit section of the interface to the
MELSEC-ST series is reinforced-isolated from the hazardous voltage circuit.
(3) Reinforced isolation
Reinforced isolation refers to the isolation with the dielectric withstand voltage
shown in Table 11.1.
Table 11.1 : Reinforced Isolation Withstand Voltage
(Installation Category II, source : IEC664)
Rated voltage of hazardous voltage area
Surge withstand voltage (1.2/50 s)
150VAC or below
2500 V
300VAC or below
4000 V
Summary of Contents for MELESEC-ST
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