Power Supply; Control Panel - Mitsubishi Electric MELSEC-A series User Manual

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3.2.3 Power supply

The insulation specification of the power module was designed assuming installation
category II. Be sure to use the installation category II power supply to the
programmable controller.
The installation category indicates the durability level against surge voltage
generated by a thunderbolt. Category I has the lowest durability; category IV has the
highest durability.
Category II indicates a power supply whose voltage has been reduced by two or
more levels of isolating transformers from the public power distribution.

3.2.4 Control panel

Because the programmable controller is an open device (a device designed to be
stored within another module), be sure to use it after storing in the control panel.
(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 panel must have the following functions:
(a) The control panel 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 panel must have a structure which automatically stops the power
supply when the box is opened.
(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. The insulation in our programmable controller is designed to cope with the
pollution level 2, so use in an environment with pollution level 2 or below.
Pollution level 1 : An environment where the air is dry and conductive dust does not
Pollution level 2 : An environment where conductive dust
Pollution level 3 : An environment where conductive dust exits and conductivity may be
Pollution level 4 : Continuous conductivity may occur due to rain, snow, etc. An
As shown above, the programmable controller can realize the pollution level 2
when stored in a control panel equivalent to IP54.
Category IV
Category III
Figure 1.: Installation Category
does not usually exist, but occasional temporary conductivity occurs
due to the accumulated dust. Generally, this is the level for inside the
control panel equivalent to IP54 in a control room or on the floor of a
typical factory.
generated due to the accumulated dust.
An environment for a typical factory floor.
outdoor environment.
Category II
Category I


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