Danfoss VLT AutomationDrive FC 360 Design Manual

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Danfoss VLT AutomationDrive FC 360 Design Manual Manual pdf 61 page image

4.7 Special ConditionsUnder some special conditions, where the operation of thefrequency converter is challenged, consider derating. Insome conditions, derating must be done manually.In other conditions, the frequency converter automaticallyperforms a degree of derating when necessary. This isdone to ensure the performance at critical stages wherethe alternative could be a trip.4.7.1 Manual DeratingManual derating must be considered for:• Air pressure–for installation at altitudes above 1km.• Motor speed–at continuous operation at low RPMin constant torque applications.• Ambient temperature–above 45 °C (for sometypes above 50 °C), for details, see Table 4.15 andTable 4.16.Enclosure size Power size[kW]Maximum outputcurrent at 45 °CMaximum outputcurrent at 50 °CJ10.37 1.2 1.20.55 1.7 1.70.75 2.2 2.21.1 3.0 3.01.5 3.7 3.02.2 5.3 4.1J23 7.2 7.24 9.0 9.05.5 12.0 10.2J3 7.5 15.5 13.1J4 11 23.0 23.015 31.0 26.0J5 18.5 37.0 37.022 42.5 40.0J630 61 6137 73 7345 90 77J7 55 106 10675 147 125Table 4.15 Derating at 380 VEnclosure size Power size[kW]Maximum outputcurrent at 45 °CMaximum outputcurrent at 50 °CJ10.37 1.1 1.10.55 1.6 1.60.75 2.1 2.11.1 3.0 2.81.5 3.4 2.82.2 4.8 3.8J23 6.3 6.34 8.2 8.25.5 11.0 9.4J3 7.5 14.0 11.9J4 11 21.0 21.015 27.0 22.6J5 18.5 34.0 34.022 40.0 37.7J630 52 5237 65 6545 77 76J7 55 96 9675 124 117Table 4.16 Derating at 480 V4.7.2 Automatic DeratingThe frequency converter constantly checks for criticallevels:• Critical high temperature on the control card orheatsink.• High motor load.• Low motor speed.• Protection signals (overvoltage/undervoltage,overcurrent, ground fault and short circuit) aretriggered.As a response to a critical level, the frequency converteradjusts the switching frequency.Specifications Design GuideMG06B402 Danfoss A/S © 09/2014 All rights reserved. 594 4