4-8
PL-7900 Series User Manual
Installation and Wiring
• If voltage fluctuations are expected to vary
beyond the specified range, connect a con-
stant voltage transformer.
For information about
the specified voltage, refer to
2-1
General Specifications
• Use a low-noise power supply both be-
tween the lines and between the PL and
its ground. If there is still excess noise,
connect an insulating transformer
(noise-prevention type).
Be sure any constant or insulat-
ing
transformer used has a capacity
of 200VA or more.
• Wire the power cords of the PL, I/O de-
vices, and power supply devices sepa-
rately.
• To improve noise immunity, it is recom-
mended to attach a ferrite core to the power
cord.
• Isolate the main circuit (high voltage, large
current) line, I/O signal lines, and power
cord, and do not bind or group them to-
gether.
• To prevent damage from lightning, con-
nect a lightning surge absorber.
• Ground the lightning surge
absorber (E1) and the PL
(E2) separately.
• Select a lightning surge
absorber which will not
exceed the allowable cir-
cuit voltage, even when the
voltage rises to the maxi-
mum.
Constant
voltage
transformer
Twisted-pair
cable
PL
FG
Insulating
transformer
Twisted-pair
cable
PL
FG
Main power
source
PL power
source T1
T2
I/O power
source
PL
I/O
device
I/O
device
Main circuit
power source
Power
device
AC200V
Twisted-pair
cable
PL
FG
Lightning surge absorber
AC
E1
E2
AC 100V
PL power
source
I/O power
source
PL
I/O
device
Main power
source
2
Power Supply Cautions
When connecting the PL unit’s AC power terminals, please be aware of the following:
Reference
Note:
!!!!!
Important
Summary of Contents for PL-7900 Series
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