NOTICE!
All VLT
®
AQUA Drive adjustable frequency drives are
equipped with integrated line interference chokes as
standard.
3.3.6 Classication of the Operating Site
Knowing the requirements for the environment the
adjustable frequency drive is intended to operate in is the
most important factor regarding EMC compliance.
3.3.6.1 Environment 1/Class B: Residential
Operating sites connected to the public low-voltage power
grid, including light industrial areas, are classied as
Environment 1/Class B. They do not have their own high-
voltage or medium-voltage distribution transformers for a
separate line power system. The environment classications
apply both inside and outside buildings. Some general
examples are business areas, residential buildings,
restaurants, car parks, and entertainment facilities.
3.3.6.2
Environment 2/Class A: Industrial
Industrial environments are not connected to the public
power grid. Instead, they have their own high-voltage or
medium-voltage distribution transformers. The
environment classications apply both inside and outside
the buildings.
They are dened as industrial and are characterized by
specic electromagnetic conditions:
•
The presence of scientic, medical or industrial
devices.
•
Switching of large inductive and capacitive loads.
•
The occurrence of strong magnetic elds (for
example, due to high currents).
3.3.6.3
Special Environments
In areas with medium-voltage transformers clearly
demarcated from other areas, the user decides which type
of environment to classify their facility. The user is
responsible for ensuring the electromagnetic compatibility
necessary to enable the trouble-free operation of all
devices within specied conditions. Some examples of
special environments are shopping centers, supermarkets,
gas stations, oce buildings, and warehouses.
3.3.6.4
Warning Labels
When an adjustable frequency drive does not conform to
Category C1, provide a warning notice. This is the responsi-
bility of the user. Interference elimination are based on
classes A1, A2, and B in EN 55011. The user is ultimately
responsible for the appropriate classication of devices and
the cost of remedying EMC problems.
3.3.7 Use with Isolated Input Source
Most utility power in the United States is referenced to
ground. Although not in common use in the United States,
the input power may be an isolated source. All Danfoss
adjustable frequency drives may be used with isolated
input source as well as with ground reference power lines.
3.3.8
Power Factor Correction
Power factor correction equipment serves to reduce the
phase shift (φ) between the voltage and the current to
move the power factor closer to unity (cos φ). This is
necessary when a large number of inductive loads, such as
motors or lamp ballasts, are used in an electrical distri-
bution system. Adjustable frequency drives with an
isolated DC link do not draw any reactive power from the
line power system or generate any phase power-factor
correction shifts. They have a cos φ of approximately 1.
For this reason, speed-controlled motors do not have to
take into account when dimensioning power factor
correction equipment. However, the current drawn by the
phase-correction equipment rises because adjustable
frequency drives generate harmonics. The load and heat
factor on the capacitors increases as the number of
harmonic generators increases. As a result,
t chokes in the
power-factor correction equipment. The chokes also
prevent resonance between load inductances and the
capacitance. Drives with cos φ <1 also require chokes in
the power factor correction equipment. Also consider the
higher reactive power level, for cable dimensions.
3.3.9
Input Power Delay
To ensure that the input surge suppression circuitry
performs correctly, observe a time delay between
successive applications of input power.
System Integration
VLT
®
AQUA Drive FC 202
56 Danfoss A/S © 09/2014 All rights reserved. MG20N622
33
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