Planning the electrical installation
54
Power factor compensation capacitors
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 three phase
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: Ensure that the connection steps are low enough not
to cause voltage transients that would trip the drive.
3. Check that the power factor compensation unit is suitable for use in systems with
AC drives i.e. harmonic generating loads. In such systems, the compensation unit
should typically be equipped with a blocking reactor or harmonic filter.
Equipment connected to the motor cable
Installation of safety switches, contactors, connection boxes, etc.
To minimize the emission level when safety switches, contactors, connection boxes
or similar equipment are installed in the motor cable between the drive and the
motor:
• EU: Install the equipment in a metal enclosure with 360 degrees grounding for the
shields of both the incoming and outgoing cable, or connect the shields of the
cables otherwise together.
• US: Install the equipment in a metal enclosure in a way that the conduit or motor
cable shielding runs consistently without breaks from the drive to the motor.
Bypass connection
WARNING! Never connect the supply power to the drive output terminals U2, V2
and W2. If frequent bypassing is required, employ mechanically connected switches
or contactors. Mains (line) voltage applied to the output can result in permanent
damage to the unit.
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