Danfoss VLT FC 102 Series Design Manual

Also see for VLT HVAC Drive FC 102: Operating instructions Service guide Programming guide Installation guide Installation guide

Contents

130BT621.12DCAGFigure 3.22 Enclosure Types B4 - C3 - C4A Top coverB BrimC Base partD Base coverE Screw(s)F Fan coverG Top clipTable 3.14 Legend to Figure 3.21 and Figure 3.21When option module A and/or option module B is/areused, the brim (B) must be fitted to the top cover (A).NOTICE!Side-by-side installation is not possible when using theIP21/IP4X/TYPE 1 Enclosure Kit.3.1.15 Output FiltersThe high speed switching of the adjustable frequencydrive produces some secondary effects, which influencethe motor and the enclosed environment. These sideeffects are addressed by two different filter types, thedU/dt and the sine-wave filter.dU/dt filtersMotor insulation stresses are often caused by thecombination of rapid voltage and current increase. Therapid energy changes can also be reflected back to the DCline in the inverter and cause shutdown. The dU/dt filter isdesigned to reduce the voltage rise time/the rapid energychange in the motor and by that intervention avoidpremature aging and flashover in the motor insulation.dU/dt filters have a positive influence on the radiation ofmagnetic noise in the cable that connects the adjustablefrequency drive to the motor. The voltage wave form isstill pulse shaped but the dU/dt ratio is reduced incomparison with the installation without filter.Sine-wave filtersSine-wave filters are designed to allow only lowfrequencies to pass. High frequencies are consequentlyshunted away, which results in a sinusoidal phase-to-phasevoltage waveform and sinusoidal current waveforms.With the sinusoidal waveforms, the use of specialadjustable frequency drive motors with reinforcedinsulation is no longer needed. The acoustic noise from themotor is also damped as a consequence of the wavecondition.Besides the features of the dU/dt filter, the sine-wave filteralso reduces insulation stress and bearing currents in themotor thus leading to prolonged motor lifetime and longerperiods between services. Sine-wave filters enable use oflonger motor cables in applications where the motor isinstalled far from the adjustable frequency drive. Thelength is unfortunately limited because the filter does notreduce leakage currents in the cables.Selection Design Guide72 Danfoss A/S © Rev. 06/2014 All rights reserved. MG11BC2233