Danfoss FC 100 Series Operating Instructions Manual

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Danfoss FC 100 Series Operating Instructions Manual Manual pdf 145 page image

9.2 Special Conditions9.2.1 Purpose of DeratingDerating must be taken into account when using the frequen-cy converter at low air pressure (heights), at low speeds, withlong motor cables, cables with a large cross section or at highambient temperature. The required action is described in thissection.9.2.2 Derating for Ambient Temperature90% frequency converter output current can be maintainedup to max. 50 °C ambient temperature.With a typical full load current of EFF 2 motors, full outputshaft power can be maintained up to 50 °C.For more specific data and/or derating information for othermotors or conditions, please contact Danfoss.9.2.3 Automatic Adaptations to EnsurePerformanceThe frequency converter constantly checks for critical levels ofinternal temperature, load current, high voltage on theintermediate circuit and low motor speeds. As a response to acritical level, the frequency converter can adjust the switchingfrequency and / or change the switching pattern in order toensure the performance of the frequency converter. Thecapability to automatically reduce the output current extendsthe acceptable operating conditions even further.9.2.4 Derating for Low Air PressureThe cooling capability of air is decreased at lower air pressure.Below 1000 m altitude no derating is necessary but above1000 m the ambient temperature (TAMB ) or max. outputcurrent (I out ) should be derated in accordance with the showndiagram.Illustration 9.1: Derating of output current versus altitudeat TAMB, MAX for frame sizes A, B and C. At altitudes above 2km, please contact Danfoss regarding PELV.An alternative is to lower the ambient temperature at highaltitudes and thereby ensure 100% output current at highaltitudes. As an example of how to read the graph, thesituation at 2 km is elaborated. At a temperature of 45° C (TAMB,MAX - 3.3 K), 91% of the rated output current is available. At atemperature of 41.7° C, 100% of the rated output current isavailable.Derating of output current versus altitude at T AMB, MAX for frame sizes D, E and F.Specifications VLT® HVAC Drive Operating InstructionsMG.11.AD.02 - VLT® is a registered Danfoss trademark 1459 9