ABB ACS880-07C, Hardware Manual

Page: 65 / 188

Guidelines for planning the electrical installation 65
Implementing a bypass connection
If bypassing is required, employ mechanically and/or electrically interlocked contactors
between the motor and the drive and between the motor and the power line. Make sure
with interlocking that the contactors cannot be closed simultaneously.
WARNING! Never connect the drive output to the electrical power network. The
connection may damage the drive.
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
230 V AC
230 V AC
+ 24 V DC
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1
2
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4