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20. EMC AND LOW VOLTAGE DIRECTIVES
20.2.4 Control panel
Because the PLC is an open type device (a device designed to be stored within another
device), be sure to use it inside the control panel.
*
* Also, each network remote station needs to be installed inside the control panel.However, the
waterproof type remote station can be installed outside the control panel.
(1) Shock protection
To prevent personnel such as operators who are not familiar with electricity from
electric shocks, the control panel must be handled as follows:
(a) Lock the control panel so that only the qualified personnel can open it.
(b) Provide a mechanism so that opening the control panel will automatically stop
the power supply.
(c) For electric shock protection, use IP20 or greater control panel.
(2) Dustproof and waterproof features
The control panel also has the dustproof and waterproof functions. Insufficient
dustproof and waterproof features lower the insulation withstand voltage, resulting in
insulation destruction. As our PLCs are designed assuming the pollution level 2, use
them in an environment of pollustion level 2 or lower.
As shown above, the PLC can meet pollution level 2 when stored in a control panel
equivalent to IP54.
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,
however, temporary conductivity may occasionally occur due to
accumulated dust. Generally, this is the level for the inside of the
IP54-equivalent control panel in a control room or on a shop floor.
Pollution level 3: An environment where conductive dust exits and conductivity may
be generated due to accumulated dust. An environment for a
typical factory floor.
Pollution level 4: Continuous conductivity may occur due to rain, snow, etc. An
outdoor environment.
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