YOKOGAWA FA-M3V e-RT3 Plus, Hardware Manual

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A3-31
IM 34M06C11-01E
(4) Leakage Current Considerations
There are cases in which a 2-wire sensor (proximity switch, photoelectric switch, etc.) or
a limit switch with an LED indicator may cause faulty input signal generation or
illumination due to leakage current. There is no problem if the leakage current is smaller
than the “off current” that is specified for the module. In situations in which it is likely
that the leakage current exceeds the off current, however, add a bleeder resistance as
shown in the figure below to lower the input impedance.
R
2-wire
sensor, etc.
Power source
Bleeder resistor
DC input module
W
x
K [mW]
Ein2
R
Rin x VOFF
Rin x I-VOFF
R
where
Rin=
Ein
lin
Note: Ensure that K

2.
R : bleeder resistor (kO)
Rin : input impedance of the DC input module (kO)
Ein : rated input voltage of the DC input module (V)
Iin
: rated input current of the DC input module (mA)
Voff : OFF voltage of the DC input module (V)
I
: leakage current of the device (mA)
W : wattage of the bleeder resistor (mW)
K : power margin of the bleeder resistor
FA030610.VSD
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