Automatic Adaptations To Ensure Performance - Danfoss FC 300 Design Manual

4. FC 300 Selection
4.7.5. Derating for Installing Long Motor Cables or Cables with Larger
Cross-Section
The maximum cable length for the FC 301 is 246 ft [75 m] when unshielded, and 164 ft [50 m]
when shielded. For the FC 302, it is 984 ft [300 m] unshielded and 492 ft [150 m] shielded
The adjustable frequency drive has been designed to work using a motor cable with a rated cross-
section. If a cable with a larger cross-section is used, reduce the output current by 5% for every
step the cross-section is increased.
(Increased cable cross-section leads to increased capacity to ground, and thus an increased
4
ground leakage current).

4.7.6. Automatic adaptations to ensure performance

The adjustable frequency drive constantly checks for critical levels of internal temperature, load
current, high voltage on the intermediate circuit and low motor speeds. As a response to a critical
level, the adjustable frequency drive can adjust the switching frequency and/or change the
switching pattern in order to ensure the performance of the drive.
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MG.33.B9.22 - VLT ® is a registered Danfoss trademark.
FC 300 Design Guide