Derating - GE AF-600 FP Series Design And Installation Manual

Installation Consideration
WARNING
Installation at high altitude:
380 - 480 V, unit size 1x, 2x and 3x: At altitudes above 2
km, please contact GE regarding PELV.
380 - 480V, unit size 4x, 5x and 6x: At altitudes above 3
km, please contact GE regarding PELV.
525 - 690 V: At altitudes above 2 km, please contact GE
regarding PELV.

7.5 Derating

7.5.1 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.
7.5.2 Derating for Ambient Temperature
7 7
90% frequency converter output current can be
maintained up to max. 50 °C ambient temperature.
With a typical full load current of EFF 2 motors, full output
shaft power can be maintained up to 50 °C.
For more specific data and/or derating information for
other motors or conditions, please contact GE.
7.5.3 Automatic Adaptations to Ensure
Performance
The frequency converter 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 frequency converter can adjust the
switching frequency and / or change the switching pattern
in order to ensure the performance of the frequency
converter. The capability to automatically reduce the
output current extends the acceptable operating
conditions even further.
7.5.4 Derating for Low Air Pressure
The cooling capability of air is decreased at lower air
pressure.
Below 1000 m altitude no derating is necessary but above
1000 m the ambient temperature (T
current (I ) should be derated in accordance with the
out
shown diagram.
62
TM
AF-600 FP Design and Installation Guide
) or max. output
AMB
DET-768b
Illustration 7.4 Derating of output current versus altitude at T
for unit sizes 1x, 2x and 3x. At altitudes above 2 km, please
MAX
contact GE regarding PELV.
An alternative is to lower the ambient temperature at high
altitudes and thereby ensure 100% output current at high
altitudes. As an example of how to read the graph, the
situation at 2 km is elaborated. At a temperature of 45° C
(T - 3.3 K), 91% of the rated output current is
AMB, MAX
available. At a temperature of 41.7° C, 100% of the rated
output current is available.
Illustration 7.5 Derating of Output Current versus Altitude at
T for Unit Sizes 4x, 5x and 6x
AMB, MAX
Illustration 7.6 Derating of Output Current versus Altitude at
T for Unit Sizes 4x, 5x and 6x
AMB, MAX
AMB,