Danfoss VLT 6000 HVAC Series User Manual

Peak voltage on motor
When a transistor in the inverter is opened, the voltage
across the motor increases by a dV/dt ratio that de-
pends on:
-
the motor cable (type, cross-section, length
screened or unscreened)
-
inductance
The natural induction causes an overshot U
PEAK
in the
motor voltage before it stabilises 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 (a few
metres), the rise time and peak voltage are lower.
If the motor cable is long (100 m), the rise time and
peak voltage will increase.
If very small motors are used without phase coil insu-
lation, it is recommended to fit a LC filter after the
frequency converter.
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 = Mains voltage x 1.35).
3.
dU
/
dt =
0.5 × U
PEAK
Risetime
Data are measured according to IEC 60034-17.
VLT 6002-6011 / 380-460 V
Cable
length
Mains
volt-
age
Rise time
Peak
voltage
dU/dt
50 metres 380 V 0.3 µsec. 850 V 2000 V/
µsec.
50 metres 500 V 0.4 µsec. 950 V 2600 V/
µsec.
150 me-
tres
380 V 1.2 µsec. 1000 V 667 V/µsec.
150 me-
tres
500 V 1.3 µsec. 1300 V 800 V/µsec.
VLT 6016-6122 / 380-460 V
Cable
length
Mains
volt-
age
Rise time
Peak
voltage
dU/dt
32 metres 380 V 0.27 µsec. 950 V 2794 V/
µsec.
70 metres 380 V 0.60 µsec. 950 V 1267 V/
µsec.
132 me-
tres
380 V 1.11 µsec. 950 V 685 V/µsec.
VLT 6152-6352 / 380-460 V
Cable
length
Mains
volt-
age
Rise time
Peak
voltage
dU/dt
70 me-
tres
400 V 0.34
µsec.
1040 V 2447 V/µsec.
VLT 6402-6602 / 380-460 V
Cable
length
Mains
volt-
age
Rise time
Peak
voltage
dU/dt
29 me-
tres
500 V
0.71
µsec.
1165 V 1389 V/µsec.
29 me-
tres
400 V
0.61
µsec.
942 V 1233 V/µsec.
VLT 6002-6011 / 525-600 V
Cable
length
Mains
volt-
age
Rise time
Peak
voltage
dU/dt
35 me-
tres
600 V
0.36
µsec.
1360 V 3022 V/µsec.
VLT 6016-6072 / 525-600 V
Cable
length
Mains
volt-
age
Rise time
Peak
voltage
dU/dt
35 me-
tres
575 V 0.38
µsec.
1430 V 3011 V/µsec.
VLT 6102-6402 / 525-600 V
Cable
length
Mains
voltage
Rise time
Peak
voltage
dU/dt
25 me-
tres
575 V 0.45
µsec.
1159 1428 V/
µsec.
VLT 6502-6652 / 525-600 V
Cable
length
Mains
voltage
Rise time
Peak
voltage
dU/dt
25 me-
tres
575 V 0.25
µsec.
1159 2510 V/
µsec.
VLT
®
6000 HVAC Series
MG.61.B5.02 - VLT
®
is a registered Danfoss trademark 197
All about VLT 6000
HVAC

Danfoss VLT 6000 HVAC Series Specifications

General

Brand	Danfoss
Model	VLT 6000 HVAC Series
Category	DC Drives
Language	English