ABB ACS550-02 User Manual page 15

Protecting the Relay Output Contacts and Attenuating Disturbances in
Case of Inductive Loads
Inductive loads (relays, contactors, motors) cause voltage transients when switched
off.
It is highly recommended to 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 OMIO board terminal block.
Varistor
230 VAC
RC filter
230 VAC
Diode
24 VDC
OMIO
X1
Digital outputs
19 RO1C
20 RO1A
21 RO1B
22 RO2C
23 RO2A
24 RO2B
25 RO3C
26 RO3A
27 RO3B
13
Installation