WARNING!
When the vector control mode is in use, never open the output contactor while the
drive controls the motor. The vector control operate extremely fast, much faster
than it takes for the contactor to open its contacts. When the contactor starts
opening while the drive controls the motor, the vector control will try to maintain
the load current by immediately increasing the drive output voltage to the maximum.
This will damage, or even burn the contactor completely.
￭ Implementing a bypass connection
If bypassing is required, employ mechanically 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. The installation must be
clearly marked as defined in IEC/EN 61800-5-1, subclause 6.5.3, for example, “THIS
MACHINE STARTS AUTOMATICALLY”.
Bypass connection is available as a factory-installed option for some cabinet-installed drive
types. Consult ABB for more information.
WARNING!
Never connect the drive output to the electrical power network. The connection
may damage the drive.
￭ Implementing the ATEX-certified Safe motor disconnection function
(option +Q971)
With option +Q971, the drive provides ATEX-certified safe motor disconnection without
contactor using the drive Safe torque off function. For more information, see
•
ATEX-certified Safe disconnection function, Ex II (2) GD for ACS880 drives (+Q971)
Application guide (3AUA0000132231 [English]).
•
FPTC-02 ATEX-certified thermistor protection module, Ex II (2) GD (option +L537+Q971)
for ACS880 drives user's manual (3AXD50000027782 [English]).
•
CPTC-02 ATEX-certified thermistor protection module, Ex II (2) GD (option +L537+Q971)
user's manual (3AXD50000030058 [English]).
￭ 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]) 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.
80 Guidelines for planning the electrical installation
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