Switching The Motor Power Supply From Direct-On-Line To Drive; Protecting The Contacts Of Relay Outputs - ABB ACS880-07XT Series Hardware Manual

74 Guidelines for planning the electrical installation

Switching the motor power supply from direct-on-line to drive

1. Stop the motor with S42.
2. Switch the motor power supply from direct-on-line to the drive with S40.
3. Close the main contactor of the drive with switch S11 (-> turn to position ST for two
seconds and leave to position 1).
4. Start the drive and the motor with the drive control panel (drive in the local control
mode) or the external start signal (drive in the remote control mode).

Protecting the contacts of relay outputs

Inductive loads (relays, contactors, motors) cause voltage transients when switched off.
The relay contacts on the drive control unit are protected with varistors (250 V) against
overvoltage peaks. In spite of this, it is highly recommended that inductive loads are
equipped 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 relay outputs.
1) Relay outputs; 2) Varistor; 3) RC filter; 4) diode
1
230 V AC
2
230 V AC
+ 24 V DC
3
4
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