Before Opening A Contactor (Dtc Control Mode Selected); Protecting The Relay Output Contacts And Attenuating Disturbances In Case Of Inductive Loads - ABB ACS800-U4 Hardware Manual

Before opening a contactor (DTC control mode selected)

Stop the drive and wait for the motor to stop before opening a contactor between the
output of the drive and the motor when the DTC control mode is selected. See the
appropriate ACS800 Control Program Firmware Manual for the required parameter
settings. Otherwise, the contactor will be damaged. In scalar control, the contactor
can be opened with the drive running.
Protecting the relay output contacts and attenuating disturbances in case
of inductive loads
Inductive loads (relays, contactors, motors) cause voltage transients when switched
off.
The relay contacts on the RMIO board are protected with varistors (250 V) against
overvoltage peaks. In spite of this, 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 RMIO board terminal block.
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: info@clrwtr.com
Varistor
230 V AC
RC filter
230 V AC
Diode
24 VD C
RMIO
Relay outputs
X25
1 RO1
2 RO1
3 RO1
X26
1 RO2
2 RO2
3 RO2
X27
1 RO3
2 RO3
3 RO3
Planning the electrical installation
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