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

Product Specifications
l
(%)
out
HO
110%
100%
90%
80%
60%
40%
20%
0
0 1 2
Illustration 6.31 Output current derating with switching
frequency and ambient temperature for 600 V frequency
6 6
converters, enclosure types C; SFAVM, HO
Enclosure Type C, T7
60° AVM - Pulse Width Modulation
I out (A)
34
28.9
27.2
20.4
13.6
1 2
Illustration 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
40
20
1 2
Illustration 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.
78
®
VLT AutomationDrive FC 301/FC 302 Design Guide, 0.25-75 kW
o
45 C
o
50 C
f
(kHz)
sw
4 6 8 10
C2 all options
45°C
50°C
55°C
f sw (kHz)
4 6 8 10
C2 all options
45°C
50°C
55°C
f (kHz)
sw
4 6 8 10
I out (%)
110%
100%
80%
C1 & C2
60%
40%
20%
0
0 2
Illustration 6.34 Output current derating with switching
frequency and ambient temperature for enclosure type C3

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 frequency converter, it is strongly
recommend to install a dU/dt filter or LC filter on the
output of the frequency converter.
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, screened,
or unscreened)
The natural induction causes an overshoot voltage peak in
the motor voltage before it stabilises. 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 (a few metres), the rise time and
peak voltage are lower. The rise time and peak voltage
increase with cable length (100 m).
The frequency converter complies with IEC 60034-25 and
IEC 60034-17 for motor design.
200-240 V (T2)
Mains
Cable voltage
length [m] [V]
5 240
50 240
100 240
150 240
Table 6.13 P5K5T2
MG33BF02 - Rev. 2013-12-20
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)
4 6 8 10
Rise time Upeak dU/dt
[μs] [kV] [kV/μs]
0.13 0.510 3.090
0.23 2.034
0.54 0.580 0.865
0.66 0.560 0.674