Derating - GE AF-650 GP Design And Installation Manual

Installation Consideration
The functional galvanic isolation (a and b on drawing) is
for the 24 V back-up option and for the RS485 standard
bus interface.
WARNING
Installation at high altitude:
380–500 V, unit size 1x, 2x and 3x: At altitudes above 2
km, contact GE regarding PELV.
380–500 V, unit size 4x, 4xh, 5x and 6x: At altitudes
above 3 km, contact GE regarding PELV.
525–690 V: At altitudes above 2 km, 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-
7 7
section or at high ambient temperature. The required
action is described in this section.
7.5.2 Derating for Ambient Temperature
90% frequency converter output current can be
maintained up to maximum 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, 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.
82
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
out
shown diagram.
Illustration 7.4 Derating of output current versus altitude at
T for unit sizes 1x, 2x, and 3x. At altitudes above 2 km,
AMB, MAX
contact GE regarding PELV.
An alternative is to lower the ambient temperature at high
altitudes and as a result of that 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
output current is 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, 4xh, 5x, and 6x
AMB, MAX
DET-767c All rights reserved.
) or max. output
AMB
) should be derated in accordance with the
- 3.3 K), 91% of the rated
AMB, MAX
MG35M402