Mitsubishi MELESEC-ST User Manual page 107

10 MOUNTING AND INSTALLATION
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(b) The 24VDC wire should be twisted as dense as possible. Connect the
modules with the shortest wire.
Also, to reduce the voltage drop to the minimum, use the thickest wires
possible.
(c) Do not install the 24VDC wire together with main circuit (high voltage, large
current) and I/O signal lines or bring them close to each other. The space of
at least 100 mm should be ensured.
(d) As a countermeasure to power surge due to lightening, connect a surge
absorber for lightening as shown below.
AC
Surge absorber for lightening
POINT
(1) Separate the ground of the surge absorber for lightening (E1) from that of the
MELSEC-ST system (E2).
(2) Select a surge absorber for lightening of which power supply voltage will not
exceed the maximum allowable circuit voltage even at the time of maximum
power supply voltage elevation.
External SYS.
power supply
External AUX.
power supply
E1
MELSEC-ST
MELSEC-ST
I/O device
E2
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