Toshiba SX 2000 - Manual (Page 132)

3.2 Precautions for AC Input Modules
3.2 Precautions for AC Input Modules
(1) The conditions to read the ON/OFF state of the input signals are as follows.
Input ON time ^ time (OFF^ON)+lnput reading cycle
Input OFF time ^ time (ON^OFFN)+lnput reading time
The "input reading cycle" means the S2T scan cycle for the refresh input,
or the execution interval of a direct input instruction when the instruction is
used.
(2) When an AC output sensor is connected to the I/O module, due to the leak­
age current from the sensor at OFF, there may be a voltage which exceeds
the maximum OFF voltage between the input terminals. This will make the
S2T unable to read input OFF when the sensor is OFF. In the case, install
a bleeder resistor between the input terminals to lower the input
impedance.
AC output type sensor Bleeder resistor Input module
(An example of selecting a bleeder resistor R)
Input module IN635 x
Input impedance: 10KQ(50Flz)
^ OFF voltage: 30Vac _
Input voltage V=100Vac (SOFIz)
When the voltage between input terminals is Vd at the switch OFF state
(with no bleeder resistor), the resistance (R) and the wattage (P) of bleeder
resistor can be selected as follows.
10[k^xR 30[V]
>25[V]
10[k^^ 10[kQ]
As a result,
R<50[kQ] ^^20[kQ]
P =
_(100[V])2
200p[Q]
x(2.5-3)5f1.5[W]
(3)
Also, when the bleeder resistor is selected in the above manner, the load
current at the sensor ON state should be checked.
10rkOl X F?
Sensor output load current=100[V]x + Rl5fmAl
If external lines foe AC input become longer with using a multi-core cable,
induced current may flow to a open wire from charges wires due to the
electrostatic capacity of the cable, causing an erroneous ON input. In this
case, install a bleeder resistor between the input terminals to lower the
input impedance. Or, you had better apply the DC input.
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