Line Power Integration; Line Power Configurations And Emc Effects; Low-Frequency Line Interference - Danfoss VLT AQUA Drive FC 202 Design Manual

System Integration
The amount of leakage current detected by the RCD
depends on the cut-off frequency of the RCD.
3 3
Leakage current [mA]
Figure 3.9 Influence of the RCD Cut-off Frequency on Leakage
Current

3.3 Line Power Integration

3.3.1 Line Power Configurations and EMC
Effects
There are several types of AC line power systems for
supplying power to adjustable frequency drives. Each
affects the EMC characteristics of the system. The 5-wire
TN-S systems are regarded as best for EMC, while the
isolated IT system is the least desirable.
System type Description
TN Line
Power
Systems
TN-S
TN-C
54
100 Hz
2 kHz
100 kHz
There are two types of TN line power distribution
systems: TN-S and TN-C.
A 5-wire system with separate neutral (N) and
protective ground (PE) conductors. It provides the
best EMC properties and avoids transmitting
interference.
A 4-wire system with a common neutral and
protective ground (PE) conductor throughout the
system. The combined neutral and protective
ground conductor results in poor EMC character-
istics.
Danfoss A/S © 09/2014 All rights reserved.
®
VLT AQUA Drive FC 202
System type Description
TT Line
Power
Systems
IT Line
Power
System
Table 3.14 AC Line Power System Types

3.3.2 Low-frequency Line Interference

3.3.2.1 Non-sinusoidal Line Power Supply
The AC line voltage is rarely a uniform sinusoidal voltage
with constant amplitude and frequency. This is partly due
to loads that draw non-sinusoidal currents from line power
or have non-linear characteristics, such as computers,
television sets, switching power supplies, energy-efficient
lamps, and adjustable frequency drives. Deviations are
unavoidable and permissible within certain limits.
3.3.2.2 EMC Directives Compliance
In most of Europe, the basis for the objective assessment
of the quality of line power is the Electromagnetic
Compatibility of Devices Act (EMVG). Compliance with this
regulation ensures that all devices and networks connected
to electrical distribution systems fulfill their intended
purpose without generating problems.
Standard
EN 61000-2-2, EN
61000-2-4, EN 50160
EN 61000-3-2,
61000-3-12
EN 50178
Table 3.15 EN Design Standards for Line Power Quality
3.3.2.3 Interference-free Adjustable
Every adjustable frequency drive generates line
interference. Present standards only define frequency
ranges up to 2 kHz. Some drives shift the line interference
in the region above 2 kHz, which is not addressed by the
standard, and label them as interference-free. Limits for
this region are currently being studied. Adjustable
frequency drives do not shift line interference.
A 4-wire system with a grounded neutral
conductor and individual grounding of the drive
units. It has good EMC characteristics when
grounded properly.
An isolated 4-wire system with the neutral
conductor either not grounded or grounded via
an impedance.
Definition
Defines the AC line voltage limits to
observe in public and industrial power
grids.
Regulates line interference generated by
connected devices.
Monitors electronic equipment for use in
power installations.
Frequency Drives
MG20N622