
9. EMC DIRECTIVE AND LOW-VOLTAGE INSTRUCTION
9 - 10
MELSEC-A
9.2.4
Control box
Because the PLC is an open device (a device designed to be stored within another
module), be sure to use it after storing in the control box.
(1)
Electrical shock prevention
In order to prevent persons who are not familiar with the electric facility such
as the operators from electric shocks, the control box must have the following
functions :
(a)
The control box must be equipped with a lock so that only the personnel
who has studied about the electric facility and have enough knowledge
can open it.
(b)
The control box must have a structure which automatically stops the
power supply when the box is opened.
(2)
Dustproof and waterproof features
The control box also has the dustproof and waterproof functions. Insufficient
dustproof and waterproof features lower the insulation withstand voltage,
resulting in insulation destruction. The insulation in our PLC is designed to
cope with the pollution level 2, so use in an environment with pollustion level 2
or below.
Pollution level 1 :
An environment where the air is dry and conductive
dust does not exist.
Pollution level 2 :
An environment where conductive dust
does not usually exist, but occasional temporary
conductivity occurs due to the accumulated dust.
Generally, this is the level for inside the control box
equivalent to IP54 in a control room or on the floor of
a typical factory.
Pollution level 3 :
An environment where conductive dust exits and
conductivity may be generated due to the
accumulated dust.
An environment for a typical factory floor.
Pollution level 4 :
Continuous conductivity may occur due to rain,
snow, etc. An outdoor environment.
As shown above, the PLC can realize the pollution level 2 when stored in a
control box equivalent to IP54.
9.2.5
Module installation
(1)
Installing modules contiguously
In AnS 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 100/200
V AC 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 (A1SG60).
When using the A1S5
B expansion base with no power supply, attach the
cover packaged with the expansion base to the side of the leftmost module.
Содержание A1SH
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