Omron CS1G/H-CPUxxH Instructions Manual page 20

Conformance to EC Directives
Circuit
Diode method
Power
supply
Varistor method
Power
supply
Current
AC DC
No Yes The diode connected in parallel with
the load changes energy accumulated
by the coil into a current, which then
flows into the coil so that the current
will be converted into Joule heat by the
resistance of the inductive load.
This time lag, between the moment the
circuit is opened and the moment the
load is reset, caused by this method is
longer than that caused by the CR
method.
Yes Yes The varistor method prevents the impo-
sition of high voltage between the con-
tacts by using the constant voltage
characteristic of the varistor. There is
time lag between the moment the cir-
cuit is opened and the moment the load
is reset.
If the supply voltage is 24 or 48 V,
insert the varistor in parallel with the
load. If the supply voltage is 100 to
200 V, insert the varistor between the
contacts.
When switching a load with a high inrush current such as an incandescent
lamp, suppress the inrush current as shown below.
Countermeasure 1
OUT
COM
Providing a dark current of
approx. one-third of the rated
value through an incandescent
lamp
Characteristic
R
Required element
The reversed dielectric strength value
of the diode must be at least 10 times
as large as the circuit voltage value.
The forward current of the diode must
be the same as or larger than the load
current.
The reversed dielectric strength value
of the diode may be two to three times
larger than the supply voltage if the
surge protector is applied to electronic
circuits with low circuit voltages.
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Countermeasure 2
R
OUT
COM
Providing a limiting resistor
6
xxi