Acoustic Noise; Vibration And Shock; Aggressive Atmospheres; Gases - Danfoss VLT AutomationDrive FC 301 Design Manual

System Integration

5.1.5 Acoustic Noise

Acoustic noise from the frequency converter comes from 3
sources
•
DC-link (intermediate circuit) coils
•
RFI filter choke
•
Internal fans
See chapter 6.2.9 Acoustic Noise for acoustic noise ratings.

5.1.7 Aggressive Atmospheres

5.1.7.1 Gases

Aggressive gases, such as hydrogen sulphide, chlorine, or ammonia can damage frequency converter electrical and
mechanical components. Contamination of the cooling air can also cause the gradual decomposition of PCB tracks and door
seals. Aggressive contaminants are often present in sewage treatment plants or swimming pools. A clear sign of an
aggressive atmosphere is corroded copper.
In aggressive atmospheres, restricted IP enclosures are recommended along with conformal-coated circuit boards. See
Table 5.1 for conformal-coating values.
NOTICE
The frequency converter comes standard with class 3C2 coating. On request, class 3C3 coating is available.
Gas type
Sea salt n/a
Sulphur oxides
mg/m
Hydrogen sulphide
mg/m
Chlorine
mg/m
Hydrogen chloride
mg/m
Hydrogen fluoride
mg/m
Ammonia
mg/m
Ozone
mg/m
Nitrogen
mg/m
Table 5.1 Conformal-coating Class Ratings
Maximum values are transient peak values not to exceed 30 minutes per day.

5.1.7.2 Dust Exposure

Installation of frequency converters in environments with
high dust exposure is often unavoidable. Dust affects wall
or frame mounted units with IP55 or IP66 protection
rating, and also cabinet mounted devices with IP21 or IP20
protection rating. Take the 3 aspects described below into
account when frequency converters are installed in such
environments.
Reduced Cooling
Dust forms deposits on the surface of the device and
inside on circuit boards and the electronic components.
These deposits act as insulation layers and hamper heat
transfer to the ambient air, reducing the cooling capacity.
®
VLT AutomationDrive FC 301/FC 302 Design Guide, 0.25-75 kW
Unit 3C1
Average value
None Salt mist
3 0.1 0.3
0.01 0.1
3
3 0.01 0.1
3 0.01 0.1
3 0.003 0.01
0.3 1.0
3
3 0.01 0.05
3 0.1 0.5
MG33BF02 - Rev. 2013-12-20

5.1.6 Vibration and Shock

The frequency converter tested according to a procedure
based on the IEC 68-2-6/34/35 and 36. These tests subject
the unit to 0.7 g forces, over the range of 18 to 1,000 Hz
random, in 3 directions for 2 hours. All Danfoss frequency
converters comply with requirements that correspond to
these conditions when the unit is wall or floor mounted, as
well as when mounted within panels bolted to walls or
floors.
Class
3C2
Max. value Average value
Salt mist
1.0 5.0
0.5 3.0
0.03 0.3
0.5 1.0
0.03 0.1
3.0 10
0.1 0.1
1.0 3.0
The components become warmer. This causes accelerated
aging of the electronic components, and the service life of
the unit decreases. Dust deposits on the heat sink in the
back of the unit also decrease the service life of the unit.
Cooling Fans
The airflow for cooling the unit is produced by cooling
fans, usually located on the back of the device. The fan
rotors have small bearings into which dust can penetrate
and act as an abrasive. This leads to bearing damage and
fan failure.
Filters
High-power frequency converters are equipped with
cooling fans that expel hot air from the interior of the
5
3C3
Max. value
10
10
1.0
5.0
3.0
35
0.3
9.0
47
5