33
POINT
(1) Separate the ground of the surge absorber for lightening (E1) from that of
the programmable controller (E2).
(2) Select a surge absorber for lightening whose power supply voltage does
no exceed the maximum allowable circuit voltage even at the time of
maximum power supply voltage elevation.
(2) Wiring to I/O device
(a) The solderless terminal with insulation sleeve is inapplicable to a
terminal block.
It is advisable to cover the wire connection part of a terminal with a mark
tube or insulation tube.
(b) Install wiring to a terminal block using the cable of core diameter 0.3 to
0.75mm
2
, and outside diameter 2.8mm or less.
(c) Run the I/O line and output line away from each other.
(d) When the main circuit line and power line cannot be separated, use a
shielding cable and ground it on the programmable controller side.
However, ground it on the opposite side in some cases.
Programmable controller
Input
Output
DC
Shielded cable
Shield jacket
RA
(e) When cables are run through pipes, securely ground the pipes.
(f) Run the 24VDC input line away from the 100VAC and 200 VAC lines.
(g) The cabling of 200m (656.2ft.) or longer distance may produce leakage
current depending on the capacity between lines and result in an
accident.
(h) As a countermeasure against the power surge due to lightning,
separate the AC wiring and DC wiring and connect a surge absorber for
lightning as shown in (i) of item (1).
Failure to do so increases the risk of I/O device failure due to lightning.
