User`s manual

MELSEC System Q, Hardware 7
General safety information and precautions
The following safety precautions are intended as a general guideline for using PLC systems to-
gether with other equipment. These precautions must always be observed in the design, in-
stallation and operation of all control systems.
P
DANGER:
● Observe all safety and accident prevention regulations applicable to your specific
application. Always disconnect all power supplies before performing installation
andwiringwork or opening any of the assemblies,components and devices.
● Assemblies, components and devicesmust 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.
● You are responsible for taking the necessary precautions to ensure that programs
interrupted 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.
● 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
possibility of undefined control system states caused by signal line cable or core
breaks.