Danfoss FC 300 Design Manual page 83

FC 300 Design Guide
4.7. Special Conditions
4.7.1. Purpose of derating
Derating must be taken into account when using the adjustable frequency drive at low air pressure
(high elevations), 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.
4.7.2. Derating for Ambient Temperature
The average temperature (T
than the maximum allowed ambient temperature (T
If the adjustable frequency drive 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
4.1: Derating of I
closure A, using 60 PWM
When using only 33 ft [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 recom-
mended derating.
4.3: Derating of I
closure A, using 60 PWM and a maximum of 32 ft.
[10 m] motor cable
) measured over 24 hours must be at least 9° F [5° C] lower
AMB, AVG
for different T for en-
out AMB, MAX
for different T for en-
out AMB, MAX
MG.33.B9.22 - VLT ® is a registered Danfoss trademark.
).
AMB,MAX
SFAVM - Stator Frequency Asyncron
Vector Modulation
4.2: Derating of I for different T
out
closure A, using SFAVM
4.4: Derating of I for different T
out
closure A, using SFAVM and a maximum of 32 ft.
[10 m] motor cable
4. FC 300 Selection
for en-
AMB, MAX
for en-
AMB, MAX
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