If you equip the drive with a main contactor or breaker, make sure that it restores
the drive input power after a short break. The contactor must either re-connect
after the break automatically, or remain closed over the break. Depending on the
contactor control circuit design, this can require an additional hold circuit,
uninterruptible auxiliary power supply or auxiliary power supply buffering.
Note: If the power loss lasts so long that the drive trips on undervoltage, a fault
reset and a fresh start command is required to continue operation.
Implement the power-loss ride-through function as follows:
1. Enable the power-loss ride-through function of the drive (parameter 30.31).
2. If the installation is equipped with a main contactor, prevent its tripping at
the input power break. For example, use a time delay relay (hold) in the
contactor control circuit.
3. Enable the automatic restart of the motor after a short power supply break:
• Set the start mode to automatic (parameter 21.01 or 21.19, depending on
the motor control mode being used).
• Define the automatic restart time (parameter 21.18).
WARNING!
Make sure that a flying restart of the motor will not cause any danger. If you
are in doubt, do not implement the power loss ride-through function.
Using power factor compensation capacitors with the drive
Power factor compensation is not needed with AC drives. However, if a drive is to
be connected in a system with compensation capacitors installed, note the
following restrictions.
WARNING!
Do not connect power factor compensation capacitors or harmonic filters
to the motor cables (between the drive and the motor). They are not meant
to be used with AC drives and can cause permanent damage to the drive or
themselves.
If there are power factor compensation capacitors in parallel with the input of the
drive:
1. Do not connect a high-power capacitor to the power line while the drive is
connected. The connection will cause voltage transients that may trip or even
damage the drive.
2. If capacitor load is increased/decreased step by step when the AC drive is
connected to the power line, make sure that the connection steps are low
enough not to cause voltage transients that would trip the drive.
Guidelines for planning the electrical installation 83
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