Adjustable Frequency Drive, P110 - P400, T7
Cable
length [m]
AC line
voltage [V]
Rise time
[
μ
sec]
Vpeak
[kV]
dU/dt
[kV/
μ
sec]
98.4 [30]
690
0.38
1.513
3.304
98.4 [30]
575
0.23
1.313
2.750
98.4 [30]
690
1)
1.72
1.329
0.640
1) With Danfoss dU/dt filter.
Table 8.41
Adjustable Frequency Drive, P450 - P1M4, T7
Cable
length (ft [m])
AC line
voltage [V]
Rise time
[
μ
sec]
Vpeak
[kV]
dU/dt
[kV/
μ
sec]
98.4 [30]
690
0.57
1.611
2.261
98.4 [30]
575
0.25
2.510
98.4 [30]
690
1)
1.13
1.629
1.150
1) With Danfoss dU/dt filter.
Table 8.42
8.6 Special Conditions
8.6.1 Purpose of Derating
Take derating into account when using the Adjustable
frequency drive 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.
8.6.2 Derating for Ambient Temperature
90% Adjustable frequency drive output current can be
maintained up to max. 122°F [50
°
C] ambient temperature.
With a typical full load current of EFF 2 motors, full output
shaft power can be maintained up to 122°F [50
°
C].
For more specific data and/or derating information for
other motors or conditions, please contact Danfoss.
8.6.3 Automatic Adaptations to Ensure
Performance
The Adjustable frequency drive 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 Adjustable frequency
drive can adjust the switching frequency and/or change
the switching pattern in order to ensure the performance
of the Adjustable frequency drive. The capability to
automatically reduce the output current extends the
acceptable operating conditions even further.
8.6.4 Derating for Low Air Pressure
The cooling capability of air is decreased at a lower air
pressure.
Below 3,280 ft [1,000 m] altitude no derating is necessary
but above 3,280 ft [1,000 m] the ambient temperature
(T
AMB
) or max. output current (I
out
) should be derated in
accordance with the diagram shown.
Figure 8.3 Derating of output current versus altitude at T
AMB, MAX
for frame sizes A, B and C. At altitudes above 6561 ft [2 km],
please contact Danfoss 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
General Specifications and ...
VLT
®
HVAC Drive Design Guide
MG11BB22 - VLT
®
is a registered Danfoss trademark
8-27
8
8
