Planning the electrical installation 59
Protecting the contacts of relay outputs
Inductive loads (relays, contactors, motors) cause voltage transients when switched
off. The voltage transients can connect capacitively or inductively to other conductors
and cause a malfunction in the system.
Use a noise attenuating circuit (varistors, RC filters [AC] or diodes [DC]) to minimize
the EMC emission of inductive loads at switch-off. Install the noise attenuating circuit
as close as possible to the inductive load. Do not install a noise attenuating circuit at
the relay output.
1
2
3
230 V AC
+ 24 V DC
4
230 V AC
Relay outputs
Varistor
RC filter
Diode
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