Measured Values For Du/Dt Testing - Danfoss VLT AutomationDrive FC 301 Series Design Manual

Product Specifications
Enclosure Type C, T7
60° AVM - Pulse Width Modulation
I out (A)
34
28.9
27.2
20.4
13.6
1 2 4
Figure 6.32 Output current derating with switching
frequency and ambient temperature for enclosure type C2,
60° AVM. Note: The graph is drawn with the current as
absolute value and is valid for both high and normal
overload.
SFAVM - Stator Frequency Asyncron Vector Modulation
I (A)
out
100
86.6
80
66.6
60
45°C
40
50°C
20 55°C
1 2 4 6
Figure 6.33 Output current derating with switching
frequency and ambient temperature for enclosure type C2,
SFAVM. Note: The graph is drawn with the current as absolute
value and is valid for both high and normal overload.
I out (%)
110%
100%
80%
60%
40%
20%
0
0 2 4 6 8
Figure 6.34 Output current derating with switching
frequency and ambient temperature for enclosure type C3
MG33BF22
Design Guide
C2 all options
45°C
50°C
55°C
f sw (kHz)
6 8 10
C2 all options
f (kHz)
sw
8 10
I at T max
LOAD AMB
I at T max +5 °C
LOAD AMB
I at T max +5 °C
LOAD AMB
f sw (kHz)
10
Rev. 2014-04-04 All rights reserved.

6.2.7 Measured Values for dU/dt Testing

To avoid damage to motors without phase insulation
paper or other insulation reinforcement designed for
operation of the adjustable frequency drive, it is strongly
recommend to install a dU/dt filter or LC filter on the
output of the adjustable frequency drive.
When a transistor in the inverter bridge switches, the
voltage across the motor increases by a dU/dt ratio
depending on:
•
Motor inductance
•
Motor cable (type, cross-section, length, shielded,
or non-shielded)
The natural induction causes an overshoot voltage peak in
the motor voltage before it stabilizes. The level depends
on the voltage in the DC link.
Peak voltage on the motor terminals is caused by the
switching of the IGBTs. The rise time and the peak voltage
affect the service life of the motor. If the peak voltage is
too high, motors without phase coil insulation can be
adversely affected over time.
With short motor cables (several feet or meters), the rise
time and peak voltage are lower. The rise time and peak
voltage increase with cable length (330 ft [100 m]).
The adjustable frequency drive complies with IEC 60034-25
and IEC 60034-17 for motor design.
200–240 V (T2)
Cable AC line
Rise time
length voltage
[m] [V] [μs]
5 240 0.13
50 240 0.23
100 240 0.54
150 240 0.66
Table 6.13 P5K5T2
Cable AC line
Rise time
length voltage
[m] [V] [μs]
36 240 0.264
136 240 0.536
150 240 0.568
Table 6.14 P7K5T2
dU/dt
Upeak
[kV] [kV/μs]
0.510 3.090
2.034
0.580 0.865
0.560 0.674
dU/dt
Upeak
[kV] [kV/μs]
0.624 1.890
0.596 0.889
0.568 0.800
87
6 6