Danfoss FC 300, FC 200, FC 100 Design guide
MAKING MODERN LIVING POSSIBLE
Output Filters Design Guide
VLT® AutomationDrive FC 300
VLT® AQUA Drive FC 200
VLT® HVAC Drive FC 100
Contents Output Filters Design Guide
Contents
1 How to Read this Design Guide
1.1.2 Abbreviations 3
2 Safety and Conformity
2.1 Safety Precautions
2.1.1 CE Conformity and Labelling 4
3 Introduction to Output Filters
3.1 Why use Output Filters
3.2 Protection of Motor Insulation
3.2.1 The Output Voltage 5
3.3 Reduction of Motor Acoustic Noise
3.4 Reduction of High Frequency Electromagnetic Noise in the Motor Cable
3.5 What are Bearing Currents and Shaft Voltages?
3.5.1 Mitigation of Premature Bearing Wear-Out 9
3.5.2 Measuring Electric Discharges in the Motor Bearings 10
3.6 Which Filter for which Purpose
3.6.1 dU/dt Filters 12
3
4
4
5
5
5
7
8
9
12
3.6.2 Sine-wave Filters 14
3.6.3 High-Frequency Common-Mode Core Kits 16
4 Selection of Output Filters
4.1 How to Select the Correct Output Filter
4.1.1 Product Overview 17
4.1.2 HF-CM Selection 19
4.2 Electrical Data - dU/dt Filters
4.3 Electrical Data - Sine-wave Filters
4.3.1 Spare Parts/Accessories 27
4.3.2 Cable Glands for Floor Standing Filters 27
4.3.3 Terminal Kits 28
4.4 Sine-Wave Filters
4.4.1 dU/dt Filters 30
4.4.2 Sine-Wave Foot Print Filter 31
5 How to Install
5.1 Mechanical Mounting
17
17
20
22
29
32
32
5.1.1 Safety Requirements for Mechanical Installation 32
5.1.2 Mounting 32
5.1.3 Mechanical Installation of HF-CM 32
5.1.4 Earthing of Sine-wave and dU/dt Filters 33
MG.90.N5.02 - VLT® is a registered Danfoss trademark 1
Contents Output Filters Design Guide
5.1.5 Screening 33
5.2 Mechanical Dimensions
5.2.1 Sketches 34
6 How to Programme the Frequency Converter
6.1.1 Parameter Settings for Operation with Sine-wave Filter 43
Index
34
43
44
2 MG.90.N5.02 - VLT® is a registered Danfoss trademark
How to Read this Design Gui... Output Filters Design Guide
1 How to Read this Design Guide
This Design Guide will introduce all aspects of output filters
for your frequency converter; from choosing the right output
filter for the application to instructions about how to install it
and how to program the frequency converter.
Danfoss technical literature is also available online at
www.danfoss.com/BusinessAreas/DrivesSolutions/Documentations/Technical+Documentation.
1.1.1 Symbols
Symbols used in this manual
NOTE
Indicates something to be noted by the reader.
CAUTION
Indicates a general warning.
WARNING
Indicates a high-voltage warning.
Indicates default setting
✮
1.1.2 Abbreviations
Alternating current AC
American wire gauge AWG
Ampere/AMP A
Automatic Motor Adaptation AMA
Current limit I
Degrees Celsius °C
Direct current DC
Drive Dependent D-TYPE
Electro Magnetic Compatibility EMC
Electronic Thermal Relay ETR
Drive FC
Gram g
Hertz Hz
Kilohertz kHz
Local Control Panel LCP
Meter m
Millihenry Inductance mH
Milliampere mA
Millisecond ms
Minute min
Motion Control Tool MCT
Nanofarad nF
Newton Meters Nm
Nominal motor current I
Nominal motor frequency f
Nominal motor power P
Nominal motor voltage U
Parameter par.
Protective Extra Low Voltage PELV
Rated Inverter Output Current I
Revolutions Per Minute RPM
Second sec.
Synchronous Motor Speed n
Torque limit T
Volts V
I
VLT,MAX
I
VLT,N
LIM
M,N
M,N
M,N
M,N
INV
s
LIM
The maximum output current.
The rated output current
supplied by the frequency
converter.
1 1
MG.90.N5.02 - VLT® is a registered Danfoss trademark 3
Safety and Conformity Output Filters Design Guide
2 Safety and Conformity
22
NOTE
2.1 Safety Precautions
Never attempt to repair a defect filter.
Equipment containing electrical components
may not be disposed of together with domestic
waste.
It must be separately collected with electrical
and electronic waste according to local and
currently valid legislation.
MCC 101/102
Design Guide
2.1.1 CE Conformity and Labelling
What is CE Conformity and Labelling?
The purpose of CE labelling is to avoid technical trade
obstacles within EFTA and the EU. The EU has introduced the
CE label as a simple way of showing whether a product
complies with the relevant EU directives. The CE label says
nothing about the specifications or quality of the product.
The low-voltage directive (73/23/EEC)
Frequency converters must be CE labelled in accordance
with the low-voltage directive of January 1, 1997. The
directive applies to all electrical equipment and appliances
used in the 50 - 1000V AC and the 75 - 1500V DC voltage
ranges. Danfoss CE-labels in accordance with the directive
and issues a declaration of conformity upon request.
NOTE
The filters presented in this design guide are specially
designed and tested for Danfoss frequency converters (FC
102/202/301 and 302). Danfoss takes no resposibility for the
use of third party output filters.
NOTE
The phased out LC-filters that were developed for the
VLT5000 series and are not compatible with the VLT FC
100/200/300.
However, the new filters are compatible with both FC-series
and VLT 5000-series
NOTE
690V applications:
For motors not specially designed for frequency converter
operation or without double insulation, Danfoss highly
recommend the use of either dU/dt or Sine-Wave filters.
NOTE
Sine-wave filters can be used at switching frequencies higher
than the nominal switching frequency, but should never be
used at switching frequencies with less than 20% lower than
the nominal switching frequency.
NOTE
dU/dt filters, unlike Sine-wave filters, can be used at lower
switching frequency than the nominal switching frequency,
but higher switching frequency will cause overheating of the
filter and should be avoided.
Warnings
CAUTION
When in use the filter surface temperature rises. DO NOT
touch the filter during operation.
WARNING
Never work on a filter in operation. Touching the electrical
parts may be fatal - even after the equipment has been
disconnected from the frequency converter or motor.
WARNING
Before servicing the filter, wait at least the voltage discharge
time stated in the Design Guide for the corresponding
frequency converter to avoid electrical shock hazard.
4 MG.90.N5.02 - VLT® is a registered Danfoss trademark
Introduction to Output Filt... Output Filters Design Guide
3 Introduction to Output Filters
3.1 Why use Output Filters
This chapter describes why and when to use Output Filters
with Danfoss frequency converters. It is divided into 4
sections:
Protection of Motor Insulation
•
Reduction of Motor Acoustic Noise
•
Reduction of High Frequency Electromagnetic
•
Noise in Motor Cable
Bearing currents and shaft voltage
•
3.2 Protection of Motor Insulation
3.2.1 The Output Voltage
The output voltage of the frequency converter is a series of
trapezoidal pulses with a variable width (pulse width
modulation) characterized by a pulse rise-time tr.
When a transistor in the inverter switches, the voltage across
the motor terminal increases by a dU/dt ratio that depends
on:
the motor cable (type, cross-section, length,
•
screened or unscreened, inductance and
capacitance)
the high frequency surge impendance of the motor
•
Because of the impedance mismatch between the cable
characteristic impedance and the motor surge impedance a
wave reflection occurs, causing a ringing voltage overshoot
at the motor terminals - see Illustration 3.1. The motor surge
impedance decreases with the increase of motor size
resulting in reduced mismatch with the cable impedance.
The lower reflection coefficient (Γ) reduces the wave
reflection and thereby the voltage overshoot. Typical values
are given in Table 3.1.
In the case of parallel cables the cable characteristic
impedance is reduced, resulting in a higher reflection
coefficient higher overshoot. For more information please
see IEC 61800-8.
3
3
Illustration 3.1 Example of Converter Output Voltage (dotted line) and Motor Terminal Voltage After 200m of Cable (solid line)
MG.90.N5.02 - VLT® is a registered Danfoss trademark 5
Introduction to Output Filt... Output Filters Design Guide
3
Typical values for the rise time and peak voltage U
PEAK
are
measured on the motor terminals between two phases.
Two different definitions for the risetime tr are used in
practice. The international IEC standards define the rise-time
as the time between 10% to 90% of the peak voltage U
peak
The US National Electrical Manufacturers Association (NEMA)
defines the rise-time as the time between 10% and 90% of
the final, settled voltage, that is equal to the DC link voltage
UDC. See Illustration 3.2 and Illustration 3.3.
To obtain approximate values for cable lengths and voltages
not mentioned below, use the following rules of thumb:
1. Rise time increases with cable length.
2.
U
= DC link voltage x (1+Γ); Γ represents the
PEAK
reflection coefficient and typical values can be
found in table below
(DC link voltage = Mains voltage x 1.35).
0.8 ×
0.8 ×
t
(
NEMA
r
U
PEAK
(IEC)
t
r
U
DC
(NEMA)
)
values at different cable lengths
peak
3.
dU/dt =
dU/dt
=
(For dU/dt, rise time, U
please consult the drive Design Guide)
Motor power [kW]
<3.7 2000 - 5000 0.95
90 800 0.82
355 400 0.6
Table 3.1 Typical Values for Reflection Coefficients (IEC 61800-8).
Zm [Ω]
Γ
The IEC and NEMA Definitions of Risetime t
r
.
Illustration 3.2 IEC
Illustration 3.3 NEMA
Various standards and technical specifications present limits
of the admissible U
and tr for different motor types. Some
peak
of the most used limit lines are shown in Illustration 3.4
IEC 60034-17 – limit line for general purpose
•
motors when fed by frequency converters, 500V
motors.
IEC 60034-25 – limit for converter rated motors:
•
curve A is for 500V motors and curve B is for 690V
motors.
NEMA MG1 – Definite purpose Inverter Fed Motors.
•
If, in your application, the resulting U
and tr exceed the
peak
limits that apply for the motor used, an output filter should
be used for protecting the motor insulation.
6 MG.90.N5.02 - VLT® is a registered Danfoss trademark
Introduction to Output Filt... Output Filters Design Guide
3
3
Illustration 3.4 Limit Lines for U
and Risetime tr.
peak
3.3 Reduction of Motor Acoustic Noise
The acoustic noise generated by motors has three main
sources.
1. The magnetic noise produced by the motor core,
through magnetostriction
2. The noise produced by the motor bearings
3. The noise produced by the motor ventilation
When a motor is fed by a frequency converter, the
pulsewidth modulated (PWM) voltage applied to the motor
causes additional magnetic noise at the switching frequency
and harmonics of the switching frequency (mainly the
double of the switching frequency). In some applications this
is not acceptable. In order to eliminate this additional
switching noise, a sine-wave filter should be used. This will
filter the pulse shaped voltage from the frequency converter
and provide a sinusoidal phase-to-phase voltage at the
motor terminals.
MG.90.N5.02 - VLT® is a registered Danfoss trademark 7
3
Introduction to Output Filt... Output Filters Design Guide
3.4 Reduction of High Frequency Electromagnetic Noise in the Motor Cable
When no filters are used, the ringing voltage overshoot that occurs at the motor terminals is the main high-frequency noise
source. Illustration 3.5 shows the correlation between the frequency of the voltage ringing at the motor terminals and the
spectrum of the high-frequency conducted interference in the motor cable.
Besides this noise component, there are also other noise components such as:
The common-mode voltage between phases and ground at the switching frequency and its harmonics - high
•
amplitude but low frequency.
High-frequency noise (above 10MHz) caused by the switching of semiconductors - high frequency but low amplitude.
•
Illustration 3.5 Correlation Between the Frequency of the Ringing Voltage Overshoot and the Spectrum of Noise Emissions.
When an output filter is installed following effect is achieved:
In the case of dU/dt filters the frequency of the ringing oscillation is reduced below 150kHz.
•
In the case of sine-wave filters the ringing oscillation is completely eliminated and the motor is fed by a sinusoidal
•
phase-to-phase voltage.
Remember, that the other two noise components are still present. This is illustrated in the conducted emission measurements
shown in Illustration 3.7 and Illustration 3.8. The use of unshielded motor cables is possible, but the layout of the installation
should prevent noise coupling between the unshielded motor cable and the mains line or other sensitive cables (sensors,
communication, etc.). This can be achieved by cable segregation and placement of the motor cable in a separate, continuous
and grounded cable tray.
8 MG.90.N5.02 - VLT® is a registered Danfoss trademark
Introduction to Output Filt... Output Filters Design Guide
3.5 What are Bearing Currents and Shaft
Voltages?
Fast switching transistors in the frequency converter
combined with an inherent common-mode voltage (voltage
between phases and ground) generate high-frequency
bearing currents and shaft voltages. While bearing currents
and shaft voltages can also occur in direct-on-line motors,
these phenomena are accentuated when the motor is fed
from a frequency converter. The majority of bearing
damages in motors fed by frequency converters are because
of vibrations, misalignment, excessive axial or radial loading,
improper lubrication, impurities in the grease. In some cases,
bearing damages are caused by bearing currents and shaft
voltages. The mechanism that causes bearing currents and
shaft voltages is quite intricate and beyond the scope of this
Design Guide. Basically, two main mechanisms can be
identified:
Capacitive coupling: the voltage across the bearing
•
is generated by parasitic capacitances in the motor.
Inductive coupling: caused by circulating currents
•
in the motor.
The grease film of a running bearing behaves like isolation.
The voltage across the bearing can cause a breakdown of the
grease film and produce a small electric discharge (a spark)
between the bearing balls and the running track. This
discharge produces a microscopic melting of the bearing ball
and running track metal and in time it causes the premature
wear-out of the bearing. This mechanism is called Electrical
Discharge Machining or EDM.
Measures that isolate the motor shaft from the load
Use isolated bearings (or at least one isolated
•
bearing at the non-driving end NDE).
Prevent shaft ground current by using isolated
•
couplings.
Mechanical measures
Make sure that the motor and load are properly
•
aligned.
Make sure the loading of the bearing (axial and
•
radial) is within the specifications.
Check the vibration level in the bearing.
•
Check the grease in the bearing and make sure the
•
bearing is correctly lubricated for the given
operating conditions.
One of the mitigation measures is to use filters. This can be
used in combination with other measures, such as those
presented above. High-frequency common-mode (HF-CM)
filters (core kits) are specially designed for reducing bearing
stress. Sine-wave filters also have a good effect. dU/dt filters
have less effect and it is recommended to use them in
combination with HF-CM cores.
3
3
Mitigation of Premature Bearing Wear-
3.5.1
Out
There are a number of measures that can be taken for
preventing premature wearing and damage of the bearings
(not all of them are applicable in all cases – combinations
can be used). These measures aim either to provide a lowimpedance return path to the high-frequency currents or to
electrically isolate the motor shaft for preventing currents
through the bearings. Besides, there are also mechanical
related measures.
Measures to provide a low-impedance return path
Follow EMC installation rules strictly. A good high-
•
frequency return path should be provided between
motor and frequency converter, for example by
using shielded cables.
Make sure that the motor is properly grounded and
•
the grounding has a low-impedance for highfrequency currents.
Provide a good high-frequency ground connection
•
between motor chassis and load.
Use shaft grounding brushes.
•
MG.90.N5.02 - VLT® is a registered Danfoss trademark 9
129
50 - 200
MHz
130BB729.10
130B8000
3
Introduction to Output Filt... Output Filters Design Guide
3.5.2 Measuring Electric Discharges in the
Motor Bearings
The occurrence of electric discharges in the motor bearings
can be measured using an oscilloscope and a brush to pick
up the shaft voltage. This method is difficult and the
interpretation of the measured waveforms requires a deep
understanding of the bearing current phenomena. An easy
alternative is to use an electrical discharge detector
(130B8000), as shown in Illustration 3.6. Such a device
consists of a loop antenna that receives signals in the
frequency range of 50MHz – 200MHz and a counter. Each
electric discharge produces an electromagnetic wave that is
detected by the instrument and the counter is incremented.
If the counter displays a high number of discharges it means
that there are many discharges occurring in the bearing and
mitigation measures have to be taken to prevent the early
wear out of the bearing. This instrument can be used for
experimentally determining the exact number of cores
needed to reduce bearing currents. Start with a set of 2
cores. If the discharges are not eliminated, or drastically
reduced, add more cores. The number of cores presented in
the table above is a guiding value that should cover most
applications with a generous safety margin. If the cores are
installed on the drive terminals and you experiment core
saturation because of long motor cables (the cores have no
effect on bearing currents), check the correctness of the
installation. If cores keep saturating after the installation is
made according to EMC best practice, consider moving the
cores to the motor terminals.
Illustration 3.6 Electrical Discharge Detector
10 MG.90.N5.02 - VLT® is a registered Danfoss trademark
Level in dBµV
Frequency in Hz
130BT119.10
Introduction to Output Filt... Output Filters Design Guide
Illustration 3.7 Mains Line Conducted Noise, No Filter
3
3
Illustration 3.8 Mains Line Conducted Noise, Sine-wave Filter
MG.90.N5.02 - VLT® is a registered Danfoss trademark 11
3
Introduction to Output Filt... Output Filters Design Guide
3.6 Which Filter for which Purpose
Table 3.2 shows a comparison of dU/dt, Sine-wave filter, and HF-CMperformance. It can be used to determine which filter to use
with your application.
Performance criteria dU/dt filters Sine-wave filters High-frequency common-mode filters
Motor insulation
stress
Motor bearing stress Slightly reduced, only in high-
EMC performance Eliminates motor cable ringing.
Max. motor cable
length
Acoustic motor
switching noise
Relative size 15-50% (depending on power size) 100% 5 - 15%
Voltage drop
Up to 150m cable (screened/
unscreened) complies with the
requirements of IEC 60034-17
(general purpose motors). Above
this cable length the risk of “double
pulsing” (two time mains network
voltage) increases.
power motors.
Does not change the emission class.
Does not allow longer motor cables
as specified for the frequency
converter’s built-in RFI filter.
100m ... 150m
With guaranteed EMC performance:
150m screened.
Without guaranteed EMC
performance: 150m unscreened.
Does not eliminate acoustic
switching noise.
0.5% 4-10% none
Provides a sinusoidal phase-to-phase
motor terminal voltage. Complies with
1
IEC 60034-17 1 and NEMA-MG1
requirements for general purpose
motors with cables up to 500m (1km for
VLT frame size D and above).
Reduces bearing currents caused by
circulating currents. Does not reduce
common-mode currents (shaft
currents).
Eliminates motor cable ringing. Does
not change the emission class. Does not
allow longer motor cables as specified
for the frequency converter’s built-in
RFI filter.
With guaranteed EMC performance:
150m screened and 300m unscreened.
Without guaranteed EMC performance:
up to 500m (1km for VLT frame size D
and above)
Eliminates acoustic switching noise
from the motor caused by magnetostriction.
Does not reduce motor insulation stress
Reduces bearing stress by limiting
common-mode high-frequency
currents
Reduces high-frequency emissions
(above 1MHz). Does not change the
emission class of the RFI filter. Does not
allow longer motor cables as specified
for the frequency converter.
150m screened (frame size A, B, C), 300
m screened (frame size D, E, F), 300 m
unscreened
Does not eliminate acoustic switching
noise.
Table 3.2 Comparison of dU/dt and Sine-wave Filters
1) Not 690V.
2) See general specification for formula.
3.6.1 dU/dt Filters
The dU/dt filters consist of inductors and capacitors in a low
pass filter arrangement and their cut off frequency is above
the nominal switching frequency of the frequency converter.
The inductance (L) and capacitance (C) values are shown in
the tables in 4.2 Electrical Data - dU/dt Filters. Compared to
Sine-wave filters they have lower L and C values, thus they
are cheaper and smaller. With a dU/dt filter the voltage wave
form is still pulse shaped but the current is sinusoidal - see
following illustrations.
Features and benefits
dU/dt filters reduce the voltage peaks and dU/dt of the
pulses at the motor terminals. The dU/dt filters reduce dU/dt
to approx. 500V/μs.
Advantages
Protects the motor against high dU/dt values and
•
voltage peaks, hence prolongs the lifetime of the
motor
Allows the use of motors which are not specifically
•
designed for converter operation, for example in
retrofit applications
Application areas
Danfoss recommends the use of dU/dt filters in the following
applications:
Applications with frequent regenerative braking
•
Motors that are not rated for frequency converter
•
operation and not complying with IEC 600034-25
Motors placed in aggressive environments or
•
running at high temperatures
Applications with risk of flash over
•
12 MG.90.N5.02 - VLT® is a registered Danfoss trademark
130BB113.11
Upeak [kV]
15m dv/dt filter
rise time [µs]
150m dv/dt filter
50m dv/dt filter
Introduction to Output Filt... Output Filters Design Guide
Installations using old motors (retrofit) or general
•
purpose motors not complying with IEC 600034-17
Applications with short motor cables (less than
•
15m)
690V applications
•
Voltage and current with and without dU/dt filter:
Illustration 3.11 Measured dU/dt values (rise time and peak
voltages) with and without dU/dt filter using 15m, 50m and 150m
cable lengths on a 400V, 37kW induction motor.
The dU/dt value decreases with the motor cable length
whereas the peak voltage increases (see Illustration 3.11). The
U
peak
and as Udc increases during motor braking (generative) U
can increase to values above the limits of IEC 60034-17 and
thereby stress the motor insulation. Danfoss therefore
Illustration 3.9 Without Filter
recommends dU/dt filters in applications with frequent
braking. Furthermore the illustration above shows how the
U
peak
increases, the cable capacitance rises and the cable behaves
like a low-pass filter. That means longer rise-time tr for longer
cables. Therefore it is recommended to use dU/dt filters only
in applications with cable lengths up to 150m. Above 150m
dU/dt filters have no effect. If further reduction is needed,
use a sine-wave filter.
value depends on the Udc from the frequency converter
peak
increases with the cable length. As the cable length
3
3
Illustration 3.10 With dU/dt Filter
Filter features
IP00 and IP20/23/54 enclosure in the entire power
•
range
Side by side mounting with the drive
•
Reduced size, weight and price compared to the
•
sine-wave filters
Possibility of connecting screened cables with
•
included decoupling plate
Compatible with all control principles including
•
flux and VVC
Filters wall mounted up to 177A and floor mounted
MG.90.N5.02 - VLT® is a registered Danfoss trademark 13
•
above that size
PLUS
3
Introduction to Output Filt... Output Filters Design Guide
3.6.2
Sine-wave filters are designed to let only low frequencies
pass. High frequencies are consequently shunted away
which results in a sinusoidal phase to phase voltage
waveform and sinusoidal current waveforms. With the
sinusoidal waveforms the use of special frequency converter
motors with reinforced insulation is no longer needed. The
acoustic noise from the motor is also damped as a
consequence of the sinusoidal wave condition. The sinewave filter also reduces insulation stress and bearing
currents in the motor, thus leading to prolonged motor
lifetime and longer periods between services. Sine-wave
Illustration 3.12 525V - With and Without dU/dt Filter
filters enable use of longer motor cables in applications
where the motor is installed far from the frequency
converter. As the filter does not act between motor phases
and ground, it does not reduce leakage currents in the
cables. Therefore the motor cable length is limited - see
Table 3.2.
The Danfoss Sine-wave filters are designed to operate with
the VLT® FC 100/200/300. They replace the LC-filter product
range and are backwards compatible with the VLT
5000-8000 Series Drives. They consist of inductors and
capacitors in a low-pass filter arrangement. The inductance
(L) and capacitance (C) values are shown in tables in
4.3 Electrical Data - Sine-wave Filters.
Sine-wave Filters
Illustration 3.13 690V - With and Without dU/dt Filter
Source: Test of 690V 30kW VLT FC 302 with MCC 102 dU/dt
filter
Illustration 3.12 and Illustration 3.13 show how U
time behaves as a function of the motor cable length. In
installations with short motor cables (below 5-10m) the rise
time is short which causes high dU/dt values. The high dU/dt
can cause a damaging high potential difference between the
windings in the motor which can lead to breakdown of the
insulation and flash-over. Danfoss therefore recommends
dU/dt filters in applications with motor cable lengths shorter
than 15m.
peak
and rise
Features and benefits
As described above, Sine-wave filters reduce motor
insulation stress and eliminate switching acoustic noise from
the motor. The motor losses are reduced because the motor
is fed with a sinusoidal voltage, as shown in Illustration 3.12.
Moreover, the filter eliminates the pulse reflections in the
motor cable thus reducing the losses in the frequency
converter.
Advantages
Protects the motor against voltage peaks hence
•
prolongs the lifetime
Reduces the losses in the motor
•
Eliminates acoustic switching noise from the motor
•
Reduces semiconductor losses in the drive with
•
long motor cables
Decreases electromagnetic emissions from motor
•
cables by eliminating high frequency ringing in the
cable
Reduces electromagnetic interference from
•
unscreened motor cables
Reduces the bearing current thus prolonging the
•
lifetime of the motor
14 MG.90.N5.02 - VLT® is a registered Danfoss trademark
Loading...