Danfoss VLT Design Manual page 119

General Specifications and ...
The natural induction causes an overshoot U
motor voltage before it stabilizes itself at a level
depending on the voltage in the intermediate circuit. The
rise time and the peak voltage U
of the motor. If the peak voltage is too high, especially
motors without phase coil insulation are affected. If the
motor cable is short (a few metres), the rise time and peak
voltage are lower.
If the motor cable is long (100m), the rise time and peak
voltage increases.
In motors without phase insulation paper or other
insulation reinforcement suitable for operation with
voltage supply (such as a frequency converter), fit a sine-
wave filter on the output of the frequency converter.
Frequency converter, P5K5, T2
Cable
length [m]
36
50
8 8
100
150
Table 8.9
Frequency converter, P7K5, T2
Cable
length [m]
5
50
100
150
Table 8.10
Frequency converter, P11K, T2
Cable
length [m]
36
136
150
Table 8.11
Frequency converter, P15K, T2
Cable
length [m]
30
100
150
Table 8.12
118
®
VLT Refrigeration Drive Design Guide
in the
PEAK
affect the service life
PEAK
Mains Rise time
voltage [V] [μsec]
240 0.226
240 0.262
240 0.650
240 0.745
Mains Rise time
voltage [V] [μsec]
230 0.13
230 0.23
230 0.54
230 0.66
Rise time
[μsec]
240 0.264
240 0.536
240 0.568
Rise time
Mains
voltage [V] [μsec]
240 0.556
240 0.592
240 0.708
®
MG16G102 - VLT
To obtain approximate values for cable lengths and
voltages not mentioned below, use the following rules of
thumb:
1. Rise time increases/decreases proportionally with
cable length.
2. U = DC link voltage x 1.9
PEAK
(DC link voltage = Mains voltage x 1.35).
/
0.8 ×
3.
dU dt
=
Risetime
Data are measured according to IEC 60034-17.
Cable lengths are in metres.
Vpeak
[kV]
0.616
0.626
0.614
0.612
011893-0001
0.510
0.590
0.580
0.560
Vpeak
[kV]
0.624
0.596
0.568
Vpeak
[kV]
0.650
0.594
0.575
is a registered Danfoss trademark
U PEAK
dU/dt
[kV/μsec]
2.142
1.908
0.757
0.655
dU/dt
[kV/μsec]
3.090
2.034
0.865
0.674
dU/dt
[kV/μsec]
1.894
0.896
0.806
dU/dt
[kV/μsec]
0.935
0.807
0.669