Danfoss VLT AutomationDrive FC 361 Series Design Manual

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Danfoss VLT AutomationDrive FC 361 Series Design Manual Manual pdf 52 page image

7.12 dU/dt ConditionsNOTICETo avoid the premature aging of motors that are notdesigned to be used with drives, such as those motorswithout phase insulation paper or other insulationreinforcement, Danfoss strongly recommends a dU/dtfilter or a sine-wave filter fitted on the output of thedrive. For further information about dU/dt and sine-wavefilters, see the Output Filters Design Guide.When a transistor in the inverter bridge switches, thevoltage across the motor increases by a dU/dt ratiodepending on the motor cable (type, cross-section, lengthshielded or unshielded) and the inductance.The natural induction causes an overshoot UPEAK in themotor voltage before it stabilizes itself at a leveldepending on the voltage in the intermediate circuit. Therise time and the peak voltage UPEAK affect the service lifeof the motor. In particular, motors without phase coilinsulation are affected if the peak voltage is too high.Motor cable length affects the rise time and peak voltage.If the motor cable is short (a few meters), the rise time andpeak voltage are lower. If the motor cable is long (100 m(328 ft)), the rise time and peak voltage are higher.Peak voltage on the motor terminals is caused by theswitching of the IGBTs. The drive complies with thedemands of IEC 60034-25:2007 edition 2.0 regardingmotors designed to be controlled by drives. The drive alsocomplies with IEC 60034-17:2006 edition 4 regarding Normmotors controlled by drives.High-power rangeThe power sizes in Table 7.12 to Table 7.13 at theappropriate mains voltages comply with the requirementsof IEC 60034-17:2006 edition 4 regarding normal motorscontrolled by drives, IEC 60034-25:2007 edition 2.0regarding motors designed to be controlled by drives, andNEMA MG 1-1998 Part 31.4.4.2 for inverter-fed motors. Thepower sizes in Table 7.12 to Table 7.13 do not comply withNEMA MG 1-1998 Part 30.2.2.8 for general purpose motors.7.12.1 dU/dt Test Results for Enclosures J8–J9Power size [kW (hp)] Cable [m (ft)] Mains voltage [V] Rise time [μs] Peak voltage [V] dU/dt [V/μs]90–160 (125–250) 30 (98) 500 0.71 1180 1339150 (492) 500 0.76 1423 1497300 (984) 500 0.91 1557 1370200–315 (300–450) 30 (98) 500 1.10 1116 815150 (492) 500 2.53 1028 321300 (984) 500 1.29 835 517Table 7.12 IEC dU/dt Test Results for J8–J9 with Unshielded Cables and No Output Filter, 380–480 VPower size [kW (hp)] Cable [m (ft)] Mains voltage [V] Rise time [μs] Peak voltage [V] dU/dt [V/μs]90–160 (125–250) 30 (98) 500 – – –150 (492) 500 0.66 1418 1725300 (984) 500 0.96 1530 1277200–315 (300–450) 30 (98) 500 – – –150 (492) 500 0.56 1261 1820300 (984) 500 0.78 1278 1295Table 7.13 IEC dU/dt Test Results for J8–J9 with Shielded Cables and No Output Filter, 380–480 VElectrical Installation Con... VLT® AutomationDrive FC 36150 Danfoss A/S © 03/2019 All rights reserved. MG06K10277