Maximum Load for a Standard Motor at 104°F [40°C] driven by an adjustable frequency drive type VLT FCxxx
Legend: ─ ─ ─ ─Typical torque at VT load ─•─•─•─Max torque with forced cooling ‒‒‒‒‒Max torque
Note 1) Oversyncronous speed operation will result in the available motor torque decreasing inversely proportional to the increase in speed. This
must be considered during the design phase to avoid overloading the motor.
3.5.5 Derating for Installing Long Motor Cables or Cables with Larger Cross-Section
NOTE!
Applicable for drives up to 125 hp [90 kW] only.
The maximum cable length for this adjustable frequency drive is 984 ft [300 m] for unshielded cable, and 492 ft [150 m] for shielded cable.
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 ground leakage current).
3.5.6 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 adjustable frequency drive. The capability to automatically reduce the output current extends the acceptable
operating conditions even further.
3 VLT AQUA Selection VLT
®
AQUA Drive Design Guide
3-30
MG.20.N5.22 - VLT
®
is a registered Danfoss trademark
3
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