Special Conditions - Danfoss FC 100 Series Operating Instructions Manual

Specifications

9.2 Special Conditions

9.2.1 Purpose of Derating
Derating must be taken into account when using the frequen-
cy converter at low air pressure (heights), at low speeds, with
long motor cables, cables with a large cross section or at high
ambient temperature. The required action is described in this
section.
9.2.2 Derating for Ambient Temperature
90% frequency converter output current can be maintained
up to max. 50 °C ambient temperature.
With a typical full load current of EFF 2 motors, full output
shaft power can be maintained up to 50 °C.
For more specific data and/or derating information for other
motors or conditions, please contact Danfoss.
9.2.3 Automatic Adaptations to Ensure
Performance
The frequency converter constantly checks for critical levels of
internal temperature, load current, high voltage on the
intermediate circuit and low motor speeds. As a response to a
critical level, the frequency converter can adjust the switching
frequency and / or change the switching pattern in order to
ensure the performance of the frequency converter. The
capability to automatically reduce the output current extends
the acceptable operating conditions even further.
9.2.4 Derating for Low Air Pressure
The cooling capability of air is decreased at lower air pressure.
Derating of output current versus altitude at T
®
VLT HVAC Drive Operating Instructions
Below 1000 m altitude no derating is necessary but above
1000 m the ambient temperature (T
current (I
diagram.
An alternative is to lower the ambient temperature at high
altitudes and thereby ensure 100% output current at high
altitudes. As an example of how to read the graph, the
situation at 2 km is elaborated. At a temperature of 45° C (T
MAX
temperature of 41.7° C, 100% of the rated output current is
available.
for frame sizes D, E and F.
AMB, MAX
®
MG.11.AD.02 - VLT is a registered Danfoss trademark
) should be derated in accordance with the shown
out
Illustration 9.1: Derating of output current versus altitude
at T for frame sizes A, B and C. At altitudes above 2
AMB, MAX
km, please contact Danfoss regarding PELV.
- 3.3 K), 91% of the rated output current is available. At a
) or max. output
AMB
AMB,
145
9 9