Specifications

SFAVM - Stator Frequency Asyncron Vector Modulation
f
sw
(kHz)
130BB214.10
40
60
80
100
I
out
(A)
86.6
1 2 64
55°C
50°C
45°C
8 10
C2 all options
66.6
20
Illustration 9.23 Output current derating with switching
frequency and ambient temperature for enclosure typeC2,
SFAVM. Note: The graph is drawn with the current as absolute
value and is valid for both high and normal overload.
9.6.6
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
to ensure the performance of the frequency converter. The
capability for automatic output current reduction extends
the acceptable operating conditions even further.
9.6.7
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
AMB
) or max. output
current (I
out
) should be derated in accordance with the
following diagram.
Max.I
out
(%)
at T
AMB, MAX
A
Altitude (km)
enclosure
B and C
enclosure
T
at 100% I
out
D
100%
91%
82%
0 K
-5 K
-9 K
1 km 2 km 3 km
0 K
-3.3 K
-6 K
130BA418.11
AMB, MAX
(K)
Illustration 9.24 Derating of output current versus altitude at
T
AMB, MAX
for enclosure types A, B and C. At altitudes above
2000 m, contact Danfoss regarding PELV.
80
0 500
100
95
90
85
1000 1500 2000 2500 3000
Altitude (meters above sea level)*
130BB008.10
I
OUT
(%)
Illustration 9.25 An alternative is to lower the ambient
temperature at high altitudes and thereby ensure 100%
output current at high altitudes
0 500 1000 1500 2000 2500 3000
Altitude (meters above sea level)*
30
35
40
45
(°C)
Amb. Temp.
130BB009.10
HO
NO
Illustration 9.26 Example: At an altitude of 2000 m and a
temperature of 45 ° C (T
AMB, MAX
- 3.3 K), 91% of the rated
output current is available. At a temperature of 41.7 ° C, 100%
of the rated output current is available
Derating of output current versus altitude at T
AMB, MAX
for
enclosure types D, E and F.
9.6.8
Derating for Running at Low Speed
When a motor is connected to a frequency converter, it is
necessary to check that the cooling of the motor is
adequate.
The level of heating depends on the load on the motor, as
well as the operating speed and time.
Constant torque applications (CT mode)
A problem may occur at low RPM values in constant
torque applications. In a constant torque applications, a
motor may over-heat at low speeds due to less cooling air
from the motor integral fan.
Therefore, if the motor is to be run continuously at an RPM
value lower than half of the rated value, the motor must
be supplied with additional air-cooling (or a motor
designed for this type of operation may be used).
General Specifications and ...
Design Guide
MG11BC02 Danfoss A/S © Rev. 06/2014 All rights reserved. 169
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