Gas type
Unit
Class
3C1
3C2
3C3
Average
value
Maximum
value
1)
Average
value
Maximum
value
1)
Sea salt
n/a
None Salt mist
Salt mist
Sulphur
oxides
mg/
m
3
0.1
0.3
1.0
5.0
10
Hydrogen
sulphide
mg/
m
3
0.01 0.1
0.5
3.0
10
Chlorine
mg/
m
3
0.01 0.1
0.03
0.3
1.0
Hydrogen
chloride
mg/
m
3
0.01 0.1
0.5
1.0
5.0
Hydrogen
fluoride
mg/
m
3
0.003 0.01
0.03
0.1
3.0
Ammonia mg/
m
3
0.3
1.0
3.0
10
35
Ozone
mg/
m
3
0.01 0.05
0.1
0.1
0.3
Nitrogen
mg/
m
3
0.1
0.5
1.0
3.0
9.0
Table 3.2 Conformal-coating Class Ratings
1) Maximum values are transient peak values not to exceed 30
minutes per day.
3.1.7.2 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
ratings, and also cabinet-mounted devices with IP21 or
IP20 protection ratings. Consider the 3 aspects described in
this section 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.
The components become warmer, which 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, mostly located on the back of the device. The fan
rotors have small bearings into which dust can penetrate
and act as an abrasive. Dust in the bearings leads to
bearing damage and fan failure.
Filters
High-power frequency converters are equipped with
cooling f,ans that expel hot air from the interior of the
device. Above a certain size, these fans are fitted with filter
mats. These filters can become quickly clogged when used
in dusty environments. Preventive measures are necessary
under these conditions.
Periodic maintenance
Under the conditions described above, it is recommended
to clean the frequency converter during periodic
maintenance. Remove dust from the heat sink and fans,
and clean the filter mats.
3.1.8 IP Rating Definitions
Against penetration by
solid foreign objects
Against access to
hazardous parts by
First digit
0 (not protected)
(not protected)
1
≥
50 mm diameter
Back of hand
2 12.5 mm diameter
Finger
3 2.5 mm diameter
Tool
4
≥
1.0 mm diameter
Wire
5 Dust protected
Wire
6 Dust-tight
Wire
Against water
penetration with
harmful effect
Second
digit
0 (not protected)
–
1 Drops falling vertically
–
2 Drops at 15° angle
–
3 Spraying water
–
4 Splashing water
–
5 Water jets
–
6 Powerful water jets
–
7 Temporary immersion
–
8 Long-term immersion
–
More information
specifically for
First letter
A
Back of hand
B
Finger
C
Tool
D
Wire
More information
specifically for
Extra letter
H High-voltage device
–
M Device moving during
water test
–
S Device stationary during
water test
–
W Weather conditions
–
Table 3.3 IEC 60529 Definitions for IP Ratings
System Integration
VLT
®
Refrigeration Drive FC 103
38
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MG16G202
3
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