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.

4.10.2 Derating for Ambient Temperature and IGBT Switching Frequency

The average temperature (T

) measured over 24 hours must be at least 5 °C lower than the maximum allowed ambient 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 60º AVM or SFAVM in par. F-37 Adv. Switching Pattern.

Unit Sizes 1x

60º AVM - Pulse Width Modulation

Illustration 4.2: Derating of I

for different T

out

1x, using 60º AVM

When using only 10 m motor cable or less in Unit Size 1x, 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 4.4: Derating of I

for different T

out

1x, using 60º AVM and maximum 10 m motor cable

SFAVM - Stator Frequency Asyncron Vector Modulation

for Unit Size

AMB, MAX

for Unit Size

AMB, MAX

Illustration 4.3: Derating of I

for different T