Danfoss VLT AQUA Drive FC 202 - Page 189

- Loads that change quickly.
Typically, a class cannot be dened ahead of time without considering the intended equipment and processes to be used in
the environment. VLT
®
high-power drives observe the limits of Class 3 under typical supply system conditions (R
SC
>10 or
Vk
Line
<10%).
Harmonic order (h) Class 1 (V
h
%) Class 2 (V
h
%) Class 3 (V
h
%)
5 3 6 8
7 3 5 7
11 3 3.5 5
13 3 3 4.5
17 2 2 4
17˂h≤49 2.27 x (17/h) – 0.27 2.27 x (17/h) – 0.27 4.5 x (17/h) – 0.5
Table 10.45 Compatibility Levels for Harmonics
Class 1 Class 2 Class 3
THDv 5% 8% 10%
Table 10.46 Compatibility Levels for the Total Harmonic Voltage Distortion THDv
10.16.4 Harmonic Compliance
Danfoss drives comply with the following standards:
•
IEC61000-2-4
•
IEC61000-3-4
•
G5/4
10.16.5 Harmonic Mitigation
In cases where extra harmonic suppression is required, Danfoss oers the following mitigation equipment:
•
VLT
®
12-pulse Drives
•
VLT
®
Low Harmonic Drives
•
VLT
®
Advanced Harmonic Filters
•
VLT
®
Advanced Active Filters
Selecting the right solution depends on several factors:
•
The grid (background distortion, mains unbalance, resonance, and type of supply (transformer/generator).
•
Application (load
prole, number of loads, and load size).
•
Local/national requirements/regulations (such as IEEE 519, IEC, and G5/4).
•
Total cost of ownership (initial cost, eciency, and maintenance).
10.16.6 Harmonic Calculation
Use the free Danfoss MCT 31 calculation software to determine the degree of voltage pollution on the grid and needed
precaution. The VLT
®
Harmonic Calculation MCT 31 is available at www.danfoss.com.
Electrical Installation Con... Design Guide
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