Specifications

Safety guidelines

MELSEC-L Series Quick start guide III

General safety information and precautions

The following safety precautions are intended as a general guideline for using PLC systems together

with other equipment. These precautions must always be observed in the design, installation and op-

eration of all control systems.

DANGER:

● Observe all safety and accident prevention regulations applicable to your specific applica-

tion. Always disconnect all power supplies before performing installation and wiring work

or opening any of the assemblies, components and devices.

● Assemblies, components and devices must always be installed in a shockproof housing fitted

with a proper cover and fuses or circuit breakers.

● Devices with a permanent connection to the mains power supply must be integrated in the

building installations with an all-pole disconnection switch and a suitable fuse.

● Check power cables and lines connected to the equipment regularly for breaks and insulation

damage. If cable damage is found immediately disconnect the equipment and the cables

from the power supply and replace the defective cabling.

● Before using the equipment for the first time check that the power supply rating matches that

of the local mains power.

● Take appropriate steps to ensure that cable damage or core breaks in the signal lines cannot

cause undefined states in the equipment.

● You are responsible for taking the necessary precautions to ensure that programs interrupt-

ed by brownouts and power failures can be restarted properly and safely. In particular, you

must ensure that dangerous conditions cannot occur under any circumstances, even for brief

periods. EMERGENCY OFF must be switched forcibly, if necessary.

● Residual current protective devices pursuant to DIN VDE Standard 0641 Parts 1-3 are not

adequate on their own as protection against indirect contact for installations with PLC

systems. Additional and/or other protection facilities are essential for such installations.

● EMERGENCY OFF facilities conforming to EN 60204/IEC 204 and VDE 0113 must remain fully

operative at all times and in all control system operating modes.The EMERGENCY OFF facility

reset function must be designed so that it cannot ever cause an uncontrolled or undefined

restart.

● You must implement both hardware and software safety precautions to prevent the possibil-

ity of undefined control system states caused by signal line cable or core breaks.

● When using modules always ensure that all electrical and mechanical specifications and

requirements are observed exactly.