Danfoss VLT AutomationDrive FC 300 Design Manual page 71

FC 300 Design Guide
4.8. Special Conditions
4.8.1. Purpose of derating
Derating must be taken into account when using the frequency converter at low air pressure (heights), at low speeds, with long motor cables, cables
with a large cross section or at high ambient temperature. The required action is described in this section.
4.8.2. Derating for Ambient Temperature
The average temperature (T
AMB, AVG
If the frequency converter is operated at high ambient temperatures, the continuous output current should be decreased.
The derating depends on the switching pattern, which can be set to 60 PWM or SFAVM in par. 14-00.
A enclosures
60 PWM - Pulse Width Modulation
Illustration 4.1: Derating of I
closure A, using 60 PWM
When using only 10 m motor cable or less in frame size A, less derating is necessary. This is due to the fact that the length of the motor cable has a
relatively high impact on the recommended derating.
Illustration 4.3: Derating of I
closure A, using 60 PWM and maximum 10 m motor cable
) measured over 24 hours must be at least 5 °C lower than the maximum allowed ambient temperature (T
for different T for en-
out AMB, MAX
for different T for en-
out AMB, MAX
MG.33.BA.02 - VLT ® is a registered Danfoss trademark
SFAVM - Stator Frequency Asyncron Vector Modulation
Illustration 4.2: Derating of I
out
closure A, using SFAVM
Illustration 4.4: Derating of I
out
closure A, using SFAVM and maximum 10 m motor cable
4. FC 300 Selection
).
AMB,MAX
for different T for en-
AMB, MAX
for different T for en-
AMB, MAX
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