Special Conditions; Temperature-Dependentswitchfrequency; Aggressive Environments - Danfoss VLT 2800 Series Operating Instructions Manual

Special conditions

Aggressive environments

As all other electronic equipment, a frequency con-
verter contains a number of mechanical and
electronic components, which to a varying extent are
vulnerable to environmental impact.
Consequently, the frequency converter is
not to be installed in environments, where
liquids, particles or gases are in the air
that would impact and damage the electronics. Un-
less the necessary measures are taken to protect
the frequency converter, there is a risk of stoppages,
which reduce the service life of the frequency con-
verter.
Liquids can be carried through the air and condense
in the frequency converter. In addition, liquids may
facilitate galvanic corrosion of components and
metal parts. Steam, oil and brine may cause corro-
sion of components and metal parts. In these areas,
it is recommended to fit units in cabinets. As a mini-
mum, cabinets should be enclosure IP 54.
Particles in the air, such as dust particles, may lead
to mechanical, electrical and thermal faults on the
frequency converter. Typical indicators that there are
too many particles in the air are dust particles
around the frequency converter fan. In very dusty
areas, cabinet fitting of units is recommended. As a
minimum, cabinets should be enclosure IP 54.
Aggressive gases, such as sulphur, nitrogen and
chlorine compounds, together with high humidity and
temperature, facilitate possible chemical processes
on the components of the frequency converter.
These chemical processes quickly impact and dam-
age the electronics. In these areas, cabinet fitting
with fresh-air circulation in the cabinet is recom-
mended, thereby ensuring that aggressive gases are
kept away from the frequency converter.
NB!:
Fitting of frequency converters in aggressive
environments increases the risk of stoppages,
in addition to considerably reducing the service life
of the unit.
Before the frequency converter is installed, it must
be checked whether there are liquids, particles or
gases in the air. This can be done by looking at ex-
isting installations in the same environment. Typical
indicators of harmful airborne liquids are water or oil
on metal parts or corrosion of metal parts. Too many
dust particles are typically observed on top of instal-
lation cabinets and on existing electrical installations.
MG.28.A5.02 - VLT is a registered Danfoss trade mark
®
VLT 2800 Series
Indicators that there are aggressive gases in the air
are copper rails and cable ends that are black on ex-
isting electrical installations.
Derating for ambient temperature
The ambient temperature (T
mum temperature allowed. The average (T
measured over 24 hours, must be at least 5
lower. If the frequency converter operates at temper-

atures above 45 C, a derating of the rated output
current is necessary .

Temperature-dependentswitchfrequency

This function ensures the highest possible switch fre-
quency without the frequency converter becoming
thermally overloaded. The internal temperature is
the actual expression of the degree to which the
switch frequency can be based on the load, the am-
bient temperature, the supply voltage and the cable
length.
The function ensures that the frequency converter
automatically adjusts the switch frequency between
f and f (parameter 411), see drawing be-
sw,min sw, max
low.
) is the maxi-
AMB,MAX
)
AMB,AVG

C
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