Danfoss VLT AQUA Drive FC 202 Design Manual

Also see for VLT AQUA Drive FC 202: Service guide Installation guide Installation guide Operating guide Installation guide

Contents

3.4 Peak Voltage on MotorWhen a transistor in the inverter bridge switches, thevoltage across the motor increases by a dU/dt ratiodepending on:• the motor cable (type, cross-section, lengthscreened or unscreened)• inductanceThe natural induction causes an overshoot UPEAK in themotor voltage before it stabilises itself at a leveldepending on the voltage in the intermediate circuit. Therise time and the peak voltage UPEAK affect the service lifeof the motor. If the peak voltage is too high, especiallymotors without phase coil insulation are affected. If themotor cable is short (a few metres), the rise time and peakvoltage are lower.If the motor cable is long (100 m), the rise time and peakvoltage increases.In motors without phase insulation paper or otherinsulation reinforcement suitable for operation withvoltage supply (such as a frequency converter), fit a sine-wave filter on the output of the frequency converter.To obtain approximate values for cable lengths andvoltages not mentioned here, use the following rules ofthumb:1. Rise time increases/decreases proportionally withcable length.2. UPEAK = DC link voltage x 1.9(DC link voltage = Mains voltage x 1.35).3.dU /dt =0.8 ×UPEAKRisetimeData are measured according to IEC 60034-17.Cable lengths are in metres.Cable Length Specifications:Frequency converter N110 - N315, T4/380-500 VCablelength [m]Mainsvoltage[V]Rise time[μsec]Vpeak[kV]dU/dt[kV/μsec]30 400 0.26 1.180 2.109Table 3.10 N110 - N315, T4/380-500 VFrequency converter P400 - P1M0, T4/380-500 VCablelength [m]Mainsvoltage[V]Rise time[μsec]Vpeak[kV]dU/dt[kV/μsec]30 500 0.71 1.165 1.38930 400 0.61 0.942 1.23330 500 1 0.80 0.906 0.90430 400 1 0.82 0.760 0.743Table 3.11 P400 - P1M0, T4/380-500 V1) With Danfoss dU/dt filter.N110-N160, T7 (525-690 V)Cablelength [m]Mainsvoltage[V]Rise time[μsec]Vpeak[kV]dU/dt[kV/μsec]150 690 0.36 2135 2.197Table 3.12 N110-N160, T7 (525-690 V)N200-N400, T7 (525-690 V)Cablelength [m]Mainsvoltage[V]Rise time[μsec]Vpeak[kV]dU/dt[kV/μsec]150 690 0.46 2210 1.744Table 3.13 N200-N400, T7 (525-690 V)Frequency converter P450 - P1M4, T7/525-690 VCablelength [m]Mainsvoltage[V]Rise time[μsec]Vpeak[kV]dU/dt[kV/μsec]30 690 0.57 1.611 2.26130 575 0.25 2.51030 690 1) 1.13 1.629 1.150Table 3.14 P450 - P1M4, T7/525-690 V1) With Danfoss dU/dt filter.3.5 Special Conditions3.5.1 Purpose of DeratingConsider derating when using the frequency converter atlow air pressure (heights), at low speeds, with long motorcables, cables with a large cross section or at high ambienttemperature. The required action is described in thissection.3.5.2 Derating for Low Air PressureThe cooling capability of air is decreased at lower airpressure.Below 1000 m altitude no derating is necessary but above1000 m the ambient temperature (TAMB) or max. outputcurrent (Iout) derate in accordance withSelection VLT® AQUA Drive FC 202 Design Guide52 MG20Z102 - VLT® is a registered Danfoss trademark33