Omron CJ-Series Operation Manual page 19

Conformance to EC Directives
Circuit
Power
supply
Power
supply
xx
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 con-
tacts.
When switching a load with a high inrush current such as an incandescent
lamp, suppress the inrush current as shown below.
Countermeasure
OUT
COM
Providing about 1/3rd of the rated current
to an incandenscent light bulb.
Characteristic
L
+
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
L
OUT
COM
Using a limiting resistor
6
+