Danfoss VLT 5000 Series, Инструкция по эксплуатации, Страница: 213 / 240

Peak voltage on motor
When a transistor in the inverter is opened, the voltage
across the motor increases by a dU/dt ratio that de-
pends on:
- the motor cable (type, cross-section, length,
shielded or unshielded)
- inductance
The natural induction causes an overshot U
PEAK
in the
motor voltage before it stabilizes itself at a level which
depends on the voltage in the intermediate circuit. The
rise time and the peak voltage U
PEAK
affect the service
life of the motor. If the peak voltage is too high, motors
without phase coil insulation are the ones that will pri-
marily be affected. If the motor cable is short (by a few
yards), the rise time and peak voltage are lower.
If the motor cable is long (328 ft [100 m]), the rise time
and peak voltage will increase.
If very small motors without phase coil insulation are
used, it is recommended that an LC filter be fitted after
the adjustable frequency drive.
Typical values for the rise time and peak voltage
U
PEAK
are measured on the motor terminals between
two phases.
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
PEAK
= DC link voltage x 1.9
(DC link voltage = Line voltage x 1.35).
3.
dU
/
dt
=
0.5 × U
PEAK
Rise time
Data are measured according to IEC 60034-17.
VLT 5001-5011 / 380-500 V
Cable
length
AC line
voltage
Rise time
Peak
voltage
dU/dt
164 ft [50 m] 500 V 0.5 sec 1230 V 1968 V/sec
492 ft [150 m] 500 V 1 sec 1270 V 1270 V/sec
164 ft [50 m] 380 V 0.6 sec 1000 V 1333 V/sec
492 ft [150 m] 380 V 1.33 sec 1000 V 602 V/sec
VLT 5016-5102 / 380-500 V
Cable
length
AC line
voltage
Rise time
Peak
voltage
dU/dt
105 ft [32 m] 380 V 0.27 sec 950 V 2794 V/sec
230 ft [70 m] 380 V 0.60 sec 950 V 1267 V/sec
433 ft [132 m] 380 V 1.11 sec 950 V 685 V/sec
VLT 5122-5302 / 380-500 V
Cable
length
AC line
voltage
Rise time
Peak
voltage
dU/dt
230 ft [70 m] 400 V 0.34 sec 1040 V 2447 V/sec
VLT 5352-5552 / 380-500 V
Cable
length
AC line
voltage
Rise time
Peak
voltage
dU/dt
95 ft [29 m] 500 V 0.71 sec 1165 V 1389 V/sec
95 ft [29 m] 400 V 0.61 sec 942 V 1233 V/sec
VLT 5001-5011 / 525-600 V
Cable
length
AC line
volt-
age
Rise time
Peak
voltage
dU/dt
115 ft [35
m] 600 V 0.36 sec 1360 V 3022 V/sec
VLT 5016-5062 / 525-600 V
Cable
length
AC line
voltage
Rise time
Peak
voltage
dU/dt
115 ft [35 m] 575 V 0.38 sec 1430 V 3011 V/sec
VLT 5042-5352 / 525-690 V
Cable
length
AC line
voltage
Rise time
Peak
voltage
dU/dt
82 ft [25 m] 690 V 0.59 sec 1425 1983 V/sec
82 ft [25 m] 575 V 0.66 sec 1159 1428 V/sec
82 ft [25 m]
690 V
1) 1.72 sec 1329 640 V/sec
1) With Danfoss dU/dt filter.
VLT 5402-5602 / 525-690 V
Cable
length
AC line
voltage
Rise time
Peak
voltage
dU/dt
82 ft [25 m] 690 V 0.57 sec 1540 2.230 V/sec
82 ft [25 m] 575 V 0.25 sec 2.510 V/sec
82 ft [25 m]
690 V
1) 1.13 sec 1629 1.150 V/sec
1) With Danfoss dU/dt filter.
VLT
®
5000 Series
210 MG.51.C5.22 - VLT
p
is a registered Danfoss trademark.