Protecting the contacts of relay outputs
Inductive loads (relays, contactors, motors) cause voltage transients when switched
off.
Equip inductive loads with noise attenuating circuits (varistors, RC filters [AC] or
diodes [DC]) in order to minimize the EMC emission at switch-off. If not suppressed,
the disturbances may connect capacitively or inductively to other conductors in the
control cable and form a risk of malfunction in other parts of the system.
Install the protective component as close to the inductive load as possible. Do not
install protective components at the I/O terminal block.
Varis
t
or
230 V AC
RC filter
Drive
relay
ou
tput
230 V AC
Diode
24 V DC
Drive
relay
ou
tput
Drive
relay
ou
tput
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