Mitsubishi Electric MELSEC L Series User Manual page 151

(4) Control panel
(a) Protection against electric shock
Handle the control panel as follows to protect a person who does not have adequate knowledge of electrical
installation from an electric shock.
(b) Protection from dust and water
The control panel needs to be dustproof and waterproof.
Insufficient dustproof and waterproof lower the dielectric withstand of the control panel, possibly causing
dielectric breakdown.
The insulation of Mitsubishi programmable controllers is designed to be used in an environment of pollution
degree 2. Use them in an environment of pollution degree 2 or below. The environment of pollution degree 2
can be achieved when the programmable controller is installed inside the control panel with a protection degree
of IP54 or equivalent.
(5) External wiring
(a) 24VDC external power supply
For 24VDC I/O modules or intelligent function modules requiring an external power supply, connect an external
power supply of which insulation between the 24VDC circuit section and the hazardous voltage circuit section
is reinforced.
(b) External devices
For external devices connected to a programmable controller, use the one of which insulation between the
interface circuit section to the programmable controller and the hazardous voltage circuit section is reinforced
(if the device internally has a hazardous voltage circuit section).
(c) Reinforced insulation
Reinforced insulation means an insulation having the following withstand voltage.
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• Lock the control panel so that only a person who is trained and has acquired enough knowledge of
electrical installation can open the panel.
• Design the control panel so that the power supply is automatically shut off when the panel is opened.
• Use a control panel with a protection degree of IP20 or higher.
Rated voltage of hazardous voltage
150VAC or less
300VAC or less
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Surge withstand voltage (1.2/50s)
2500V
4000V
(Overvoltage category, source: IEC 664)
APPENDICES
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