2 Engineering
2.8 Motor chokes
DC1 Variable Frequency Drive 04/16 MN04020003Z-EN www.eaton.com 47
2.8 Motor chokes
It is recommended to use a motor choke if using long cable lengths and/or
connecting several motors in parallel. The motor reactor is in the output of
the variable frequency drive. Its rated operational current must always be
greater than/equal to the rated operational current of variable frequency
drive.
For DC1 variable frequency drives, it is recommended to use a motor choke
for motor cable lengths of 100 meters or more. Doing so may result in the
following improvements:
• Longer maximum permissible screened motor cable length,
up to 200 m,
• Current smoothing and du/dt value (kV/s) attenuation, providing
additional protection for the winding insulation inside the motor,
• Motor noise and heat build-up will be reduced.
Figure 17: DX-LM3… rated operational data:
U
max
= 750 V, f
2
= 0 - 400 Hz, f
PWM
= 8 - 32 kHz (P-17 setting on DC1)
It is also recommended to use a motor choke at the variable frequency
drive’s output if several motors with identical or different rated operational
data are being run in parallel (V/Hz control only). In this case, the motor choke
will compensate for the total resistance and total inductance decreases
caused by the parallel circuit and will attenuate the cables’ higher stray
capacitance.
￫
Take into account the maximum permissible motor cable
lengths for the relevant EMC interference category.
￫
For the rated motor chokes for DC1 variable frequency drives,
please refer to Section 2.8, “Motor chokes“, page 47.
For more information and technical data on DX-LM3…
motor chokes, please refer to instruction leaflet
IL00906003Z.
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